Success! ShopBot’s First Open House

On Saturday, August 24th, ShopBot Tools held their first Open House in Durham, NC. The event was free and open to the public, but because it was our first time holding one we weren’t sure what to expect. Little did we know, we would have over 200 people come see us during the 4-hour event!

Our full line of tools were on display for the Open House. Everything from our smallest tools, the Handibot® Smart Power Tool and the ShopBot Desktop, to our more specialized tools like the 5-Axis tool and Standalone Indexer. The newest tool in our line-up, the Desktop MAX ATC, was in operation showing off its capabilities by cutting a full-sized guitar body out of a block of mahogony. Our Edge Clamp Joinery Jig showed people how they are able to create precise, repeatable dovetails and joints, while also showing off the creativity one can achieve with decorative end-milling when using the jig in conjunction with the Desktop and Desktop MAX. The precision and versatility of ShopBot tools were being showcased for all that cared to look and learn.

Other tool demos involved the participation of our visitors, with some even providing an opportunity for the users to create something to bring home with them. Kids and adults alike were able to make their own badges, cut marble puzzles on the Desktop tools in our training area, draw graffiti with the help of a Handibot, and even make their own personalized chocolates. Sometimes it was difficult to tell who was having more fun, the kids or the adults!

In addition to ShopBot’s tools being on display, there were many employees at the event available to provide some in-depth tours, as well as answer questions that anyone might have about the tools and the company.

There were several raffle prizes available, including free Basic Training sessions here at ShopBot, expansive digital vector clip art libraries, and a variety of items that were cut by our own employees using our tools. Who knows what you could win when we do our next Open House? Keep your eyes out for an announcement about another one some time next year and make plans to join us.

Take a look at some of the photos from the event:

 

Digital Fabrication for Educators: Inaugural Fusion 360 Training

Fusion 360, a powerful cloud-based CAD/CAM software that is free for educators, has been gaining popularity in schools because the design files can be output to multiple digital fabrication tools such as CNC machines (like ShopBot tools), laser cutters, and 3D printers. While the price is right, sorting through the possibilities and keeping track of the design flow can be daunting for both new and experienced users of CAD/CAM software and ShopBot CNC machines. With this in mind, ShopBot’s July session of the Digital Fabrication for Educators workshop, led by Sallye Coyle and David Bryan, worked through Fusion 360 with a group of willing and patient educators.

There was a 3D printer and a laser cutter present at the workshop, but a big part of the event was for everyone to get hands on experience with setting up a CNC for machining. Whether new to the process, or with a couple of (months/years) under their belt, everyone went home with new tips and tricks for CNC use (and VCarve Pro).

Getting Started: A “Simple” Open-Faced Cube

Fusion 360 is an engineering-based 3D rendering program. Translation: Start with a 2D drawing or “sketch” on a plane or face (X, Y, or Z axis), then extrude it into a 3D rendering or “body” that can be viewed and manipulated from multiple angles on screen. Many tools in the drop-down menus (Sketch, Create, Modify) allow the user to create and manipulate models.

To create a 1” cube with an open face, one could start with drawing a rectangle with fixed dimensions in two axes (X and Y: Sketch menu). Then, extrude the cube into the Z dimension one inch (Create menu). Using the “shell” tool under the Modify menu, make the solid cube into an open-faced cube with walls that are .125” thick.

The resulting 3D model can be exported as an .stl for 3D printing or 3D carving on a ShopBot or other CNC machine. Alternatively, the 2D sketch (X and Y) of the top face with the outside and inside edge of the cube could be exported as a .dxf for use with the ShopBot. In that case, the Z dimension would be created in the toolpath option (profile or pocket) rather than taken from the 3D body itself.

3D printer starting on the 2+ hour print of the 1” cube.

Parametrics

A power of Fusion 360 is that it is parametric. Translation: instead of being dependent upon a fixed value for a dimension or parameter, one can create a “User Parameter” for the dimension. If the value of the User Parameter changes, the entire model will change accordingly. Table 1 (below) shows the original dimensions set for creating a 1” cube (bottom), and a set of User Parameters defined for the Width_X, Depth_Y, Height_Z and Wall Thickness of the cube (top.) Table 2 (below) shows how the model changes when the original dimensions are replaced with the User Parameters. It makes updating the model extremely easy. Think of building slotted furniture and being able to change the slot size (and cut depth) to reflect the actual thickness of the plywood by simply by changing the value of the User Parameter.

Table 1: Fixed Model Parameters defined in initial cube. User parameters are defined for future use.

Table 2: Fixed parameters replaced with User Parameters. Note Expression and Value changed from Table 1. 

A) 1” cube with Fixed Parameters B) Cube resized with User Parameters

The samples above are made with a single “component” (open faced cube.) The sizes are manipulated by changing the values of the “User Parameters.” Objects in blue or grey filament are 3D printed. (Time to 3D print the 1” cube at high quality: 2Hr 20 min.) Models in wood were machined on a ShopBot Buddy® from a 2” x 6” board, using the CAM features of VCarve Pro. [Time to hollow out both cubes from either 3D .stl (roughing and finish pass toolpaths) or 2D .dxf (pocket toolpath) and cut out the cubes (profile toolpath): 10 – 15 minutes total, both cubes.] Fillets in the corners can be added in the Sketch mode, the Create mode, or are a result of machining inside corners with a round, rotating bit.

Preparing 3D models for 2D laser cutting or CNC machining

Fusion isn’t just for 3D printing (additive) or 3D carving (subtractive) of models. It is also very useful for creating and inspecting the model in its 3D rendering, then preparing the various faces for 2D cutting of sheet good materials.

In the photo above, a finger-joint box is rendered in 3D, then the 2D sketches of each face have been exported for cutting out of cardboard on the laser cutter. The white and blue cube was machined out of ¼” King Color Core HDPE on a ShopBot. User Parameters were used to change the size of the models.
In the files created for the ShopBot, “dogbones” were added to the internal corners to account for the fact the closest a rotating round bit can get into an internal corner is the radius of the bit. Adding a bit more space to the internal corner means a square corner can fit into the finger joint. An add-in developed by Brian Ekins makes adding the dogbone to a Fusion 360 model as easy as clicking on the model and defining the diameter of the bit.

Adding “Components” in a Fusion Model

The first example of an open-faced cube for 3D printing or CNC machining out of a block of material is relatively simple because there is basically one part in the model. In contrast, a finger-joint box that is cut out of sheet goods is made up of several different sides. In the photo below, the open faced box has 5 different pieces: a top, a front, a back, and 2 sides. The design must take into account that the joints on the edges are not all the same because each face must fit into its corresponding joints. Top and bottom (if there was one) would be the same, Left and right have the same joints, but are mirrored from each other if the inside and outside are not interchangeable. Likewise, the front and the back have the same joints, but are mirrored from each other.

One way to keep track of the different parts is to separate them into different components. The term “component” has different meanings in different software, but for Fusion, it’s easiest to think of a component as a “level.” A component can have, within it, Sketches, Bodies and CAM set ups. It can be turned on and off to make it easier to see what one is doing. Fusion treats a “Body” differently than a Component. However, one has the ability to convert a Body into a Component to help keep track of the various parts and pieces. Yes, it is a lot to process.

Examine each side of the above model. The joints on the edges are different for each piece, though the sides and front/back are mirrors of each other.

 

Once a 2D .dxf file has been created from the 3D rendering, it can be sent to a laser cutter remotely. Heather (visiting ShopBot in Durham, NC) sent the finger joint box file to her sister in Utah, who cut it with a GlowForge laser cutter.

CAM with Fusion 360

One big difference between Vectric software (like VCarve Pro) and Fusion 360 is in setting up for the CAM (manufacturing) with a CNC machine like a ShopBot. The first question that Vectric software asks when one opens a new CAD file is “what is the size of the material,” as well as the origin of the X and Y axes and the Z axis origin. That information is carried throughout the entire design and toolpathing (CAM) options. In 2D toolpathing (profile, pocket, drill) the Z or cut depth is defined by the user. In 3D toolpaths, the Z or cut depth is defined by the 3D model.

Chris came into the class with more experience in the CAD side of Fusion 360, and used the workshop to get more familiar with the CAM side. He imported the “Georgia” as a bitmap into Fusion 360, then drew the vectors. He discovered that it might be more efficient to trace a bitmap in another software rather than hand following in Fusion 360.

In Fusion 360, one does not define the material, the origins, or how the parts fit onto the material until all the components have been designed. In its default mode, the Y axis is up, so one has to define Z as up in preferences. For the most part, Z depth is defined by the model. Paying attention to where the software is defining the start point of the model is critical. Preview the toolpath before writing the ShopBot code, read the code, and do an air-cut to avoid mistakes. And do make sure that the Z axis on the ShopBot is set up the same way as it is in the code so that the bit doesn’t plunge too deep into the material, or ride above the material, when actually running the file.

David and Sasha chose to celebrate their 23rd Anniversary by attending the class. David works with robotics students, and prefers Fusion 360 as the design software because of its engineering base and parametric qualities. He wanted more hands-on time with the ShopBot. Sasha is principal of an elementary school, and wanted to learn more about digital fabrication in general. Yes, this was a class with an emphasis on Fusion 360, but they ended up creating their final sign in VCarve Pro. It wasn’t until they were showing off their sign to their sons that they discovered their mistake. The design and toolpathing is perfect. However, the month was July =)

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A note about the workshop leaders

Sallye is fluent in Vectric software (VCarve Pro, Aspire), which is more graphic-based (think artists and signmakers) and, to her mind, more intuitive for beginners. While there are always tricks to be learned/taught, the basic workflow of CAD (what and where), to CAM (how), to creating files for the ShopBot, can be demonstrated fairly quickly in the Vectric software. For Sallye, working in Fusion 360 has been like learning Russian when her first language is Spanish: she can now maybe order a meal, or go grocery shopping, but actually having a conversation that includes jokes or writing a short story will require more practice and tutorials. Thank goodness for YouTube videos, especially Lars Christensen, Taylor Stein and Jim Yost. She pays attention to the little asides that experienced users assume that newbies will know. Sallye is looking forward to getting more CAM tips at the upcoming Fusion Academy in Portland to expand her knowledge of Fusion 360 for 3, 4, and 5 axis machining.

David has a background in Solidworks and Rhino, engineering-based 3D rendering programs. So Fusion0 360 is not quite as great a leap. He is also more fluent in 5 axis machining, since he has been working with the ShopBot 5-axis tools.

A big thank you to the patience and sense of humor of the first group to attend a Fusion 360 training while Sallye and David worked through what can be accomplished in a 2 + day workshop. We learned a lot! Let us know if you’re ready for another Fusion 360 workshop at ShopBot.

 

Making Music at the Summer NAMM Show in Nashville

Reported by Chris Burns

The National Association of Music Merchandisers holds two conferences every year. The Summer NAMM show in Nashville, TN is filled with people from all different areas of music including musicians, audio technology experts, and instrument makers, just to name a few. Some of the businesses exhibiting build hundreds of instruments every day, such as Martin, Taylor, Fender, and Gibson whereas others are small builders that put out only dozens each year. This year at the show, ShopBot exhibited for the first time and debuted the new Desktop MAX ATC with a 6-tool automatic tool changer. It was a big hit among both large and small luthiers. We were also displaying a small Becker vacuum pump and template with three cutting stations. The larger 36” x 24” cutting area of the Desktop MAX can fit a body, neck, and fingerboard and still have room for pickguards, bridges, and pegheads.

Here are some highlights from the show:

  • Tim Teel, Director of Guitar Design at Martin Guitars, stopped by the booth to see the new tool and was delighted with the size and the performance of the MAX ATC (even though we were cutting Les Paul solid bodies). Martin uses several ShopBot Desktops for cutting inlay and special parts in their development area in Nazereth, PA. I must confess I returned to the Martin booth several times to play their D-18 Modern Deluxe. Tim explained the new innovations that make this an amazing instrument. “Some ultra-modern features include a titanium truss rod, liquid-metal bridge pins with red dots, and a composite carbon fiber bridge plate that boosts volume without adding weight.” Not bad for a company that has been around since 1833. All I know is that I did not want to put it down.
  • Local Nashville musicians, Kasey Tyndall and David Dollar, stopped by to play some songs in the ShopBot booth. David brought his Elliott Tonemaster that was cut on a ShopBot Desktop a few years ago.
  • Will MacFarlane drove up from Muscle Shoals, AL to jam for a bit in the booth. Will was inducted into the Music Hall of Fame in 2012 as a friend of the Muscle Shoals Rhythm Section and has appeared on dozens of albums with the likes of Etta James, Bobby “Blue” Bland, Little Milton, Levon Helm, and Lenny LeBlanc. He also toured with Bonnie Raitt for years as her lead guitarist.
  • The ShopBot booth happened to be located just behind Chris Mitchell and the gang of gifted luthiers and musicians from Pladd Dot Music. They have been cutting their CMG guitar line and Devilcat amps for around five years on a larger ShopBot tool. We even had time to slip in some Vectric 3D training while we were together.

We were helped in our booth by longtime ShopBotter Ray Clark from Teen Challenge Women’s Ministries in Jackson, MS. Ray oversees four large PRSalpha machines (two with ATCs) that all run 40 hours/week providing job training for women recovering from substance abuse. They produce encouraging hand-painted plaques and religious themed items that are sold in several states to help support the 13-month residency program, that is provided free of charge, to the people they serve. Please visit their website to learn more, and maybe even consider helping in some way.

A very special thanks to Andy Elliott at Elliott Guitars for building such incredible instruments and loaning the ShopBot built guitars and equipment for our booth. Also, a big shout out to my friend Bob Thompson of Thompson Handcrafted Guitars in West Virginia for building my Curly Koa Dreadnought guitar. I love it! You are both gifted craftsmen with a passion for giving much more than expected to your customers.

But the best part of the show for me was spending the weekend in the booth with ShopBot’s first employee and legend, Gordon Bergfors. Gordon has had an incredible impact on the company over the last 23 years and has had his hand in every aspect of the design and manufacturing of the electronics, the software, and the hardware. Next to CEO Ted Hall, no one has contributed more to your CNC machine. He is now retiring from office work to pursue a life of digital fabrication leisure (yeah right). Thank you, Gordon, for all you have done with your time at ShopBot!

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Chris Burns is a digital fabricator from Durham, NC and works part-time for ShopBot upgrading, assembling, and training on new and used machines all over the country. You can follow Chris’ travels on Instagram at @chrisburns981.

ShopBot in Cleveland — Spring Make 19

Hone your craft. Build your brand. This was the idea behind Spring Make 19 in Cleveland, Ohio April 25th – 27th. As a first time sponsor of the event, we weren’t quite sure what to expect, but things got off to the races quickly!

The first day of the event, Thursday, April 25th, contained what were called “crash courses.” These were specifically in the areas of metals and woodworking. The Metal & Black Smith Workshop space was outfitted with welding equipment, blacksmithing tools, and just about anything someone working with metals would want access to for making things. The Wood Shop had hand tools, lathes, power tools, work benches… and both shops were in a constant state of use.

Even though this first day was meant to be a set-up day for ShopBot and other exhibitors, there were plenty of people on-site participating in the crash courses. Because of that, we found ourselves fielding questions and talking about our tools with people while we were setting up our space. It might have made set-up a little slower, but it certainly kept us busy long after the actual set-up was complete.

Friday, April 26th was the start of the “meat” of the event: Speakers, hands-on workshops, and classes. On both Friday and Saturday, there were keynote speakers to open the day, during lunch, and to close out the day. These sessions were the times when everyone—attendees, speakers, teachers, mentors, and sponsors—were in the same space at the same time. All of speakers were there to talk about topics related to creativity, but in a variety of ways. How? Via making, educating, marketing, sharing, and learning, some covering several of these areas at a time.

Then there were the hands-on workshops happening throughout Friday and Saturday, all taking place in the metal shop and the wood shop. For metals, the sessions were Forging Basics, Basic Welding. Basic Knife Making, and Sheet Metal Shaping. For wood, there were areas set aside for Woodturning, as well as mentors to help people in the realm of “Achieving  Your Best Finish.” Since we were set-up right by the wood shop, we saw all kinds of activity going on in both shops, as there was an open area between the two where people could transition back-and-forth. Some people combining what they were doing in the metal shop with things in the wood shop, and vice versa.

The classroom sessions on each day covered a wide range of things, all related to social media subject matter, whether it was about content generation (sound and video editing, CAD, photo and video styling, building things) or strategy (obtaining sponsorships, gaining subscribers, maintaining subscribers).

Whichever type of session or workshop people attended, they were there to learn. And not just from the small sessions. The keynote speakers were a huge draw when it came to this as well. A prime example of this was the lunchtime speaker on the final day, Jimmy Diresta. As a social media influencer with over 1.5 million subscribers on YouTube, Jimmy is in the kind of position that most of the people attending Spring Make aspire to be in. Full disclosure: Jimmy is a ShopBot user.)

Spring Make is the brainchild of Lincoln Electric’s Director of Marketing Communications, Craig Coffey. It was great to be a part of this group of sponsors: Lincoln Electric, Pferd, Rigid, Torchmate, JET Tools, WeldTables.com, SawStop, Woodpeckers, and Beaumont Metal Works … and we look forward to next year’s Spring Make!

 

Electronics, 3D-Carving, and Molding & Casting at Fab Labs

Soldering surface mount components to the PCB board: LED, switch, battery holder.

The first three months of 2019 saw a flurry of Professional Development in Fab Labs from Mississippi/Louisiana to California. Fab Labs have a full quiver of digital fabrication tools and a well-stocked electronics station. The goal for these Professional Development workshops or FFI’s (Fab Faculty Institute) was to do some cross-platform training that would introduce faculty and lab managers to equipment and techniques that are often underutilized. While we go into the Fab Labs with an agenda for each day, the most important aspect is for faculty and managers to have time to “mess about” with some guidance from the FFI leaders.

Simple electronics, sewing and embroidery

In Santa Clara, middle school and high school teachers expressed an interest in learning about Arduinos so that they could help their students in robotics competitions. Arduino is an “open-source electronic prototyping platform enabling users to create interactive electronic objects.” Instead of using actual physical components such as capacitors and resisters to control inputs and outputs, one can write code and load it onto the Arduino. Rather than leap to Arduino without understanding the basics of circuits and electricity, we started with some simple circuits using conductive thread or copper tape, LEDs, batteries and switches.

Basic circuits on the board.

 

Teachers using popsicle sticks, copper tape, LED’s, batteries and clips to prototype circuits.

With help from FFI leaders, one teacher used VCarve Pro to create a drawing for a circuit, machined a copper blank using a 1/16” bit on the ShopBot CNC, and soldered the surface mount components to the PCB to make a flashlight. One project, several skills.

PCB blank with a thin layer of copper on the board, machined on the ShopBot PRTalpha with a 1/16” bit.

 

A functioning flashlight.

In Jackson County, Mississippi, managers from three Fab Labs joined together: Jackson County (Vancleave, MS), NOLA (New Orleans, LA), and the newest, Jackson (Jackson, MS). They were interested in learning about the sewing/embroidery machines that often sit idle because A) sewing is a skill that is seldom taught in schools or at home B) the digitizing software is unfamiliar to them c) they had never taken the time to actually use the machines.

Again, we started with the basics: hand sewing. In a room of adults, several had never threaded a needle or tied a knot in thread. To make the project a bit more interesting, we used conductive thread to make ordinary gloves into “smart” gloves that could be used with smart phones.

Hand sewing conductive thread onto the fingertips of gloves.

 

With a simple pad of conductive thread, an ordinary glove now works with a smart phone screen.

From there, we threaded the sewing machine and used utility stitches to make a little bag, and the embroidery stitches to personalize it. What does this have to do with ShopBot? The digitizing softwares for embroidery machines are CAD programs. Many of the terms and tools used in one software are the same as the CAD software used for the ShopBot CNC or a laser cutter. Who knows which machine will spark enough of an interest in a teacher or a student to get them over their fear of using a computer-controlled or digital fabrication tool? Success on one digital fabrication tool can open up worlds.

Using utility stitches with a sewing machine.

 

Watching the embroidery machine do its thing.

 

This math teacher from Santa Clara didn’t know she could have an interest in an embroidery machine. Check out that smile after digitizing Pi, embroidering it onto fabric, and sewing up a pillow!

3D Carving, Molding and Casting

3D printing was intended for rapid prototyping of designs, and was not intended for production of multiple copies of the same thing, like rubber duckies or Yoda heads. But its rise in popularity has contributed to the development of many CAD software applications, and even 3D scanners, that can create 3D models on the computer. Many of the same files that can be used with a 3D printer can be 3D carved on a ShopBot, and the resulting model used to create molds to aid in the production of many copies.

At Santa Clara, we imported an .stl file into VCarve Pro for machining on their ShopBot PRTalpha. After sizing onto a 2”x 6” from the local building supply store, we created a roughing pass to clear out the majority of the material. We then used a ¼” ball nose bit to finish the 3D carving. Time from start to finish for the roughing and finish passes: 27 minutes.

Once we had the model, we added a bit of hot glue around the edge to give the mold a little more depth, then filled the model with a two-part flexible mold making material from Smooth-On. After it cured, we pulled the mold from the model. For this experiment, we filled the mold with melted paraffin and crayons. Think soap, plaster, or, with food-grade mold material, chocolate!

Model 3D carved on the ShopBot (27 minutes), and mold made from a two-part material from Smooth-On.

 

Some of the molding and casting materials available from Smooth-On.

 

Carefully watching the paraffin and crayons melt in a toaster oven.

 

Paraffin and crayons cast in the mold.

 

Another object cast in a 2 part mold made from a 3D printed model. Notice the “nobbies” added to align the two sides of the mold, and sprues added to allow the material to be poured into the mold, and air to escape while the material is poured in.

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The leaders of the FFI in Mississippi: Sallye Coyle and Chris Carter
The leaders of the FFI in Santa Clara: Sallye Coyle, Andrea Fields and Chris Carter (www.TIESteach.org)

Make Your Own Circuit Board Luggage Tags

If you’re like me you hate the paper tags that transportation services give you to identify your bags when you travel. Recently I decided to make myself some that were more durable and would look WAY cooler.

I dug around in the shop and found some machinable circuit board blanks that were left over from a couple of projects. Unlike traditional FR-4 circuit board blanks that are designed for chemical etching and have a fiberglass backing, the machinable FR-1 blanks have a paper and resin backing that is easier on bits… and your lungs! The ones I had were single-sided (with copper on only one side) and were 2” x 3”, but they are available in larger sizes and with copper on both sides.

I was going to machine my tags on a Handibot® Smart Power Tool which I had mounted to an mdf baseplate, so my first decision was how to hold the blank securely to the mdf while machining. There are lots of options, but the simplest was to use double-stick tape. It holds well, but can leave some sticky residue on the back of the blank. Fortunately, a layer of masking tape or vinyl applicator’s tape on the back of the blank will peel off cleanly.

I haven’t had much luck with double-stick Scotch tape so I generally use carpet tape, available at just about any hardware store. Since I want the blank to be flat and secure I covered the whole taped blank with the double-stick, but you can certainly use less if you want.

After squeegeeing everything flat, the last prep step is to peel the backing off the double-stick tape and place it in the correct location for machining. I had already made some marks on my machining surface that marked the 0,0 corner, and aligned the blank with those marks and stuck it down securely.

Design Decisions:

I had three decisions to make:

  • What size and type bit to use? I knew the bit needed to be pretty small, but wasn’t sure if I wanted to use a V-bit or a straight bit. A V-bit can make nice sharp corners, but the blanks are too thin to use a V-carving toolpath strategy and in a blank this thin, any variation in flatness would be pretty noticeable. I decided on a 1/32” straight bit from Precise Bits with a down-spiral geometry to keep from pulling the copper layer up
  • What font? Since I wasn’t going to be using a v-carving toolpath, a single line font made the most sense—and my go-to single line font in VCarve is Railway 1L

  • What shape tag? I wanted to keep it simple and decided on a rectangle with rounded corners and a hole near a corner for a ring. I wanted a couple of tags that would be almost the full size of the blank, but also wanted some with just a name and phone number. With a little fiddling two of those would fit on each blank.

Draw and Toolpath:

I started a new drawing with a 2”x3” workspace that was 0.06” thick, the size of my circuit board blanks. I created two tag blanks with a bit of space between them, drew a corner hole that fit the rings I had, and entered the text for each tag. It took a little fiddling to get the text sized and positioned correctly, but once it was done I created two toolpaths.

The first was the text which I cut 0.02” deep to cut through the copper layer, using a Profile strategy with the On The Line option. To cut the tags and holes I also used a profile strategy, this time with the Outside option. VCarve is smart enough to understand when something is “Inside” something else, so the hole was cut on its inside while the tag was cut on the outside. To make it easier on my tiny 1/32” bit this cutout was done it 2 passes, using a spiral plunge to ease into the cut and minimize the load on the bit.

The preview looked good so it was time to cut!

When the cutting was finished I popped them loose from the mdf and was really happy with how they turned out. The cuts turned out really smooth, with just a quick pass with some 220 grit sandpaper to ease any sharp edges just a bit.

Supplies:

I get the circuit board blanks from Inventables, but they are available from lots of places these days (even Amazon). Just make sure that you get FR-1 blanks that are made for machining.

There are many places to get small bits, but my go-to place is Precise Bits. They have a large selection of bits and collets, but I’ve also heard good things about Driilman1 on eBay.

Using Your ShopBot to Make a Mallet a.k.a. “a Blunt Instrument”

No matter what kind of work you do, occasionally you’ll need a “blunt instrument”–something you can use to pound on things. This is my version. I’ve made a bunch of them over the years out of odd corners of sheets of ½” plywood I was cutting, but all the parts fit nicely on a 16”x16” blank of whatever ½” material you might have laying around. I’ve included the VCarve Pro files (at the end of the post), along with these step-by-step instructions, so you can make one of your own.

There are two versions of the head. One has faces that are parallel to each other (shown on the left) and is best for general pounding. If you plan on using it to hit a chisel or something like that, I find the one with slightly angled faces (shown on the right) to be a bit more comfortable to use.

Along with the cutout plywood parts, you’ll need a few supplies. The parts are glued together using plain old carpenter’s glue (I like Titebond 3), but pretty much any wood glue will do. For temporary clamping while the glue sets, you’ll also need four ¼-20 hex bolts that are at least 3.5” long for the head, and three that are at least 1.5” long for the handle. Two flat washers and a nut will be needed for each of these bolts, along with 7/16” wrenches and a disposable brush to spread the glue. You’ll also need around 18” of ¼” dowel.

Put a washer on each of the four longer bolts and insert them into the four holes in one of the larger head parts.

 

Spread glue on the face of this piece, making sure to cover it completely. You’re better off with too much glue than too little, so be generous.

 

Add a second large plate and slide it down the bolt. Next, take two of the smaller spacers, look at how they will be assembled, and flip them over.  Spread glue all over their faces.

 

Flip them back so they are glue side down, slide them down their corresponding pair of bolts, and then repeat with the other pair of spacers.

 

Coat the face of this layer with glue.

 

Add the third large piece, coat its face with glue, then add the last plate. Put a washer and nut on each bolt and then tighten the nuts to clamp it all together. Don’t go too crazy tightening the nuts because the washers will make indentations. You want to tighten it just enough that a little of the excess glue squeezes out and it’s securely held.

 

Scrape off as much squeezed out glue as you can, especially in the open recess. It’s easier to remove it before it cures than afterwards, especially inside this area!

 

Repeat these steps with the two handle parts and the three shorter bolts. If you are using the weighted handle option, see the instructions below.

 

Set aside these parts to let the glue cure completely, then remove the bolts. Clean out the holes with a drill and a ¼” bit.

 

Cut four 3.25” lengths of ¼” dowel for the holes in the head, and three lengths that are 1.25” long for the handle. Put a little glue in each hole and drive in the dowels so that a little sticks out of both sides. Let the glue cure.

 

When this glue has cured, cut off the ends of the dowels and then sand all the edges. A belt sander works well. But any kind of sander will work and even a rasp or file if that’s all you have.

 

Next, round over the edges to make the grip more comfortable. I like to round over just the handle section that I’ll be holding, starting at the straight tapered section (the red line in this picture) and continuing around the handle to the other side. Flip and repeat.

When you’re done, sand the handle until it’s nice and smooth. Your hand will thank you!

 

I sometimes round over the edges of the head, but mostly just to keep them from getting too banged up. Sharp edges won’t stay sharp for long, especially when you’re pounding on things!

 

The slight taper in the head and handle allow you to easily insert and remove the handle. Slip the handle through the hole in the head, slide it as far as you can, then turn it over and tap it several time on a concrete floor or other solid surface. Inertia will securely tighten the head on the handle.

 

An optional weighted handle:

Sometimes you want a little more heft when you’re pounding on stuff, so included in the VCarve Pro files I provided below are optional pockets that can be cut into the handles. If you’ll be doing this version, I’d suggest cutting the parts with the “good” side of the plywood down since the pockets will be on the sides that will be glued together.

 

The pockets are mirror images so that when the two handle halves are glued together, they will create a void in the middle with an access hole on one side. You’ll glue and clamp the two halves together, just like a non-weighted handle.

 

Generously spread glue on both halves and clamp together with bolts, nuts, and washers. If there’s any gunk in the access hole, clean it out now before the glue sets.

 

After the glue has set remove the bolts, sand the edges, and glue in the dowels. Trim the dowels and round over the edges, just like a non-weighted handle.

 

Stand the handle on one edge and start filling with BBs or lead shot. Stop every once in a while to tap it on the table to level the BBs and check the weight. If you fill the cavity completely with bb’s you’ll add between 4-5 ounces of weight, which is just right for me. If you want it even heavier you can use lead shot instead of bb’s…lead weighs three times as much as steel!

 

When you have it just the way you want it you can plug the access hole using a hot glue gun, but I find a piece of Scotch Tape works well to keep things together until the mallet is assembled . Once you (carefully!) install the handle in the head, the access hole will be covered and the weights won’t fall out.

 

If you haven’t filled the cavity completely, the weights shifting around will act to minimize any rebound when pounding, but the noise may end up annoying you. If it does, squirt glue, resin, or even paint into the hole and shake it around to coat the pellets. Let it solidify completely before using.

Here are the files to make both the flat-faced and angle-faced mallet.

Due to popular demand, the files contained in the link above now include the .dxf files as well.

Tuning Up the PRS Gantry

Special Notice from ShopBot Technical Support (2019)

CAUTION – Before continuing with any of the recommended information below, the following maintenance information should be checked and double checked first, and our Technical Support team contacted before any adjustments are made to the gantry gussets or beam. The gantry is assembled in house using specialized jigs that align the beam and end plates, if the gussets are loosened, this alignment may be lost and cause further issues that are extremely difficult to rectify without the proper equipment.

First – Manually square the tool using the mechanical stops – The guide on how to do this can be found in the ShopBot 3 software under the **[H]elp->[S]quaring the X Car” drop-down. Do not adjust the gussets on the last page of this guide.

Resources:

Basic mechanical troubleshooting

Checking Pinion Play

Adjusting Lower V Wheels on YZ Car


Below is the original post published Dec 2, 2008.
Written & Published by: Gary Campbell

There are many reasons that your gantry can be out of square or plumb. The gantry can be jostled during shipping, bolts can loosen due to vibration, moving parts wear, metal can fatigue, or the machine may have had an impact. No matter what the reason, you should add checking for square and plumb to your monthly maintenance routine. After a month of our normal use, it is not unlikely that we could be off by .100” across the table. If you have a new machine you should run it for a week or two and then check for both square and plumb.

Checking for Plumb:

To check the spindle for plumb, place a framing square with the short leg on the table in the X direction and the long leg vertically alongside the spindle and against spindle mounting plate. Any gap between the square and the plate means that you will have to tip the Y extrusion in the direction needed to get plumb (perpendicular to the table). If adjustment is necessary, it will be done later.

Checking for Square:

The ShopBot manuals on squaring the X car show how to use the mechanical stops to square the gantry and hold it when powered. I prefer to have my X car square when unpowered also. This allows me to depress the reset button and have the gantry square itself. Since my mechanical stops are also set square, I can double check the car quickly when needed. One of the reasons I went down this route is that my control box cannot be reached while holding the car against the stops. Another is that my gantry is square every time I power up the machine. My method will add a few steps to the ShopBot methods.

Checking the Gantry for Square:

I wrote a short file (download the zipped file here) that cuts 3 shallow V groove crosses near the table extremities to allow us to quickly check how square our machine is cutting. To use the file you should have a fairly clean table to allow the shallow lines to be visible, a sharp V-Bit installed and have the bit zeroed to the table top.

When you run the file it will v carve 3 crosses at X, Y positions 2, 2 94.021, 2 and 2, 46. After cutting the bit will return to 2, 2 and drop to .25 off the table over the cross. The file will now pause and give you a message box with the distance of 102” from the cross at 94, 2 to the one at 2, 46. Placing a tape across those crosses “cut” 10” on the 94, 2 mark and place a short pencil mark at 112” (we are cutting 10”, remember?)

This shows the table with marks previewed and tape measure in place:
TableView

Taking time to be very accurate will pay big dividends. When you place your tape across the marks make sure it is flat and straight. You will want to use the same edge of the tape to hold both the 10” cut and make the 112” mark. If 112” is the exact measurement to the cross, your machine is square.

When you make your mark it will look like either (1) or (2) below:CrossLines

The file will now give a message box that asks you to make your mark. When you hit ENTER the file will ask for the difference. Using a digital caliper measure the distance between the cross (RED) and your pencil mark (either (1) or (2). If your mark is to the left as in (1) then your difference MUST be a negative number. The file will then display a message box and ask you for the distance from the bit to the Y = 0 (front) wheels. Measure this and enter the number (+/- .25”) Hit ENTER. CAUTION: The machine will move slightly! This will adjust the amount needed to properly square the gantry.

The file will now display a message box and tell you to clamp the X car. I do this by clamping a 2” by 6” by ¾” wood block with a ¼” deep v groove in it on either side of the wheels to the X extrusion with rubber covered bar clamps. I then use another clamp that holds the gusset down securely to the extrusion. When this is done, hit ENTER.

A message box will display and ask if you are ready to move. Hit ENTER. CAUTION: The tool will now move to the Y = 46 line and drop the bit to .125 off the table. 2 message boxes will display with instructions to loosen bolts and shut down control box. Hit ENTER at both, put SB3 software in preview mode and power down the control box.

Loosening the Bolts:

If the difference between your pencil mark and the cross was less than .100” then you should just have to loosen the bolts under the Y extrusion. (see illustration)

If the difference was greater than .100” then you will have to loosen both the under beam bolts AND the bolts thru the end plate.

If you determined earlier that you want to plumb the spindle, then you must loosen the under beam bolts, end plate bolts AND the 16 hex socket head bolts that hold the end plates to the extrusion. Whichever combination you select, you should loosen the bolts and leave them finger tight. This allows adjustments to be made, but keeps the parts close to alignment. As you make your adjustments, you may have to snug, loosen and resnug these bolts to keep parts properly aligned and get everything square, plumb and of course, level.

BEFORE LOOSENING BOLTS, PLACE A PENCIL MARK UNDER THE BIT AND WRITE DOWN THE X COORDINATE SHOWN ON THE CONTROL PANEL.

ENDView (illustration courtesy ShopBot Tools, Inc.)

Plumb Spindle:

If you are not plumbing the spindle, skip this step.

Place a clamp on the +Y end plate to insure the wheels are seated on the rail. Loosen the 8 +Y hex socket bolts ¼ turn additional. Check to see if the extrusion will tilt in the direction needed. If not, loosen all but the lower left of the –Y hex socket bolts. Move the extrusion as needed to align with framing square. Lightly snug the 8 –Y hex socket bolts. Making sure that the +Y wheels are properly seated in the rails; lightly snug those 8 bolts also. Recheck spindle. Repeat as needed. When spindle is plumb, carefully tighten all 16 hex socket bolts securing the side plates to the Y extrusion. Remove the clamp from the +Y side plate.

Square the Gantry:

IF you did not have to plumb the spindle your goal is to move the +Y end of the gantry so that the bit is over the cross. If you did tilt the extrusion, then you will need to move the +Y end of the gantry the decimal difference between the displayed X coordinate and 2”. If display is 2.15 then difference equals negative 0.15” If display is 1.85 then difference is plus 0.15. The difference is the amount to move the bit in the direction indicated. (Plus = positive X direction.) Using the caliper set to the proper number, make a new pencil mark from the mark that is under the bit. That mark is the target mark to move the bit to.

I like to move the end of the gantry past the mark and let it relax back to it. Using a block as above with a v groove in it to push the end plate to the target mark (or just past), clamp block down to X extrusion with padded clamp. Use another clamp to seat wheels on rail. In 2 stages tighten all bolts starting at the –Y side and ending with the +Y side. Release clamps and check that bit is over target mark and wheels are seated properly. If not, loosen bolts and repeat. You may have to push end plate farther beyond mark to insure that gantry “settles in” just above the target mark as you retighten bolts. Double check all bolts to insure that they are tight. YOU ARE DONE!

You may want to run the file in 2D offset (-1” X, -1”Y) to check your results. When you are satisfied that you are square, this would be a good time to adjust the stop blocks to the square gantry. We run this check anytime we notice cuts not perfectly square, and usually around once a month. Hopefully, you will find it as valuable as we do.

Prototype to Production: A Case Study

At ShopBot, we’re understandably passionate about making things with CNC machines and about the power of digital fabrication tools. We’re always looking for ways to help show what these amazing tools can do, and for items that are made with a ShopBot that showcase several of the processes that a ShopBot tool can handle. Things that use multiple materials and techniques to give a broad overview of the power of CNC in a small, tangible package.

Every once in a while, Jeanne (Director of Marketing and Sales) at ShopBot prods me for something new, but it had been a while since an idea resonated with me. Then late last year, I saw some led lights on the Amazon “deal-of-the-day” that were inexpensive and looked kind of interesting to me. They were cheap enough that on an impulse I ordered a few strings without really having a project in mind for them. I kept thinking that they looked like fireflies, and decided that I would make an updated (and more humane) version of the jars full of fireflies we used to have in our bedrooms during the summer when we were kids. Digging through the scrap pile in my shop, I found some 3” clear acrylic tube, cut caps out of plywood scrap to fit in the ends, drilled a couple of holes, and stuffed the string of lights inside the tube. When I turned it on it looked pretty neat so off it went to my buddy Robert’s daughter Rowan to help her feel like summer wasn’t too far away!

I had enough tube and strings of lights to make a couple more, so on my next trip to ShopBot HQ I took my samples along to show Jeanne. They were kind of plain looking being just a tube full of lights, but I felt that with a little bit of CNC wizardry that they could be made pretty cool looking. I described my vision to her for carving designs in the tubes, and she not only liked it, she wanted 200 of them to give out to people! This meant that I had to go from playing around with one-offs to full production!

Tools

I’ve got a pretty good assortment of ShopBot tools in my shop, and figured that I could use my Desktop MAX to cut sheets of plywood discs for the end caps and a Handibot® to carve decorations into the lids and drill and groove for the wires in the bases. To engrave the designs on the tubes, I needed an indexer—a fancy version of a lathe that is precisely controlled and synced with the motion of the rest of the tool.

I told Jeanne that I needed an indexer if she wanted me to do the engraving that would make it interesting, and went home with a second Handibot mounted over an indexer. These three machines, along with some standard shop tools like table saw and sanders, would each do their part to turn my shop into a mini-factory.

Materials

The materials were pretty easily available. The end caps were cut out of ½” baltic birch plywood, with 270 discs coming out of a 5’x5’ sheet, enough for 135 strings of lights. The full sheets were cut into 20″x30” blanks on the table saw to fit on the MAX… one of the most awkward jobs because of the size and shape of the sheets!

The acrylic tubes, 3” in diameter with ⅛” wall thickness, was purchased from Norva Plastics in Norfolk, VA. Each 6’ length yielded 15 tubes which were cut to length on a chopsaw with a stop block and a fine-toothed blade.

The lights and some sticky felt discs (to prevent sliding) to apply to the bottoms were available from Amazon, and all the shipping supplies were found in the dozens of ULine catalogs scattered around the shop

Software

I only needed two pieces of software, Google and VCarve. My idea was that I would carve fireflies around the tube, with the ShopBot logo along the bottom. I had the ShopBot logo in a suitable format but needed fireflies, so I searched Google for firefly pictures and found one that I thought would work. Using the built-in tracing function in VCarve to digitize it, I made some changes to make it more carve-able and then modified it by rotating and changing the sizes to add some variety and to keep them from looking like they were rubber-stamped.

To place the fireflies and logo around the outside of the tubes I used a feature in VCarve software that lets you project a feature onto a surface and then “wrap” it around an object like my cylindrical tube. I toolpathed all the features with a 90-degree V-bit, limiting the depth of cut to 0.03” to make sure that I left plenty of the thin ⅛” wall uncut.

After spending way too much time moving fireflies around and spinning them just a little bit. I came up with a layout that both Jeanne and I were happy with.

It’s really hard to tell from a flat preview what it will look when it’s wrapped around the tube, but fortunately VCarve has the ability to preview the final file in-the-round. This helped confirm that it would look the way I wanted.

Engraving the Tubes

Engraving the tubes with the 90 degree V-bit would take about 12 minutes per tube, which would give me plenty of time to process the plywood parts and all the other jobs while they were cutting. I made some quick modifications to the headstock of the indexer to create stops to precisely hold the tubes, but other than that it was off-the-shelf standard.

To hold the tailstock end I cut a tapered disk with the Handibot that fit into the end of the tube and kept it secure and centered.

Every 12 minutes or so, a tube would have completed the engraving steps, ready to be removed from the indexer and replaced with a new one. They didn’t require any real post-processing, other than a quick sanding of the cut edges with a random orbit sander to remove any marks from the saw, and a shot of compressed air to blow off the dust.

Fabricating the Plywood Endcaps

The plywood discs were cut on the Desktop MAX with a ¼” bit. They needed a shallow lip around their edge to keep them centered in the tubes and hold them in place, so each disc was cut in two stages. First the lip and then the cutout. A single small tab held them in the sheet during cutting, easily removed during the sanding steps.

A holding jig was created for the Handibot to keep the discs registered and securely held in place using a small toggle clamp. Half of the discs became lids with a firefly carved into it with a V-bit.

The other half of the discs became bases with a thru-hole for the wire and a groove so that it could exit from the side. These features were cut with a ⅛” straight bit.

All the plywood parts were completed with a final sanding and finished with finishing oil mixed with a little bit of clear polyurethane for durability. They were wet-sanded with 400 grit sandpaper to help fill in the porous birch’s grain, and then left to dry.

Final Assembly

I did the easy part–fabricating all the parts. Someone at the ShopBot offices got stuck assembling them all and packaging them for shipping. This involved:

  • A final cleaning.
  • Inserting a base cap into each tube.
  • Threading the LED wire through the hole in the base and pulling all 10’ through.
  • Stuffing the LED wire back into the tube and adding the top cap.
  • Hot gluing the power wire into the groove in the base and then covering it with a felt disc.
  • Wrapping for shipping, then finally boxing and labeling.

The Beans Need to Be Counted

Then came the hardest part—pricing them. After making almost 200 of them I knew pretty much exactly what it took in time and materials to make one, so it was just a matter of calculating what they should sell for to make it worthwhile…a real product that makes money.

The easiest method for me to figure it all out was to create a spreadsheet and enter every cost, broken into 3 categories: labor, materials, and machine time. Materials were easy, I had the cost figures for everything so all I had to do was add it all up. I added 100% to that figure to cover the cost of ordering, handling, and the general costs of the occasional, but inevitable, times when things go wrong and materials are unusable!

Labor was priced at $20/hour, a decent hourly rate. After listing and recording the labor costs for each step, I totaled them all, added, and again multiplied by 100% to cover costs like overhead (taxes, insurance, etc.) and general operating costs.

Machining time costs was a little more tricky. The time that someone had to spend to load and unload the tools was already included in the labor costs (including unproductive time waiting for parts to cut that only took a little time), so I calculated machine time costs to include electricity, bits, and enough to pay off the Handibot Smart Power Tools in a couple of months. I came up with $15/hour, but raised it to $25 just to give a bit of a cushion.

To reach the final selling price I totaled the labor, materials, and machine time figures and multiplied the total by 33% for profit. This made the retail price $40.15

If you’d like to play around with the numbers and see how each component impacts the final cost, here is my pricing estimation spreadsheet for you to download.

I Lied About That Being the Hardest Part…

The actual hardest part was, and still is, deciding on a name for them. Since the beginning I’ve liked the name “Tubers” because they’re…well…tubes. I continue to call them tubers even though Jeanne insists that it’s a stupid name for anything not involving a potato. She’ll win of course, but I’ll go down fighting!

_________________________

For more about the ShopBot Desktop MAX, visit the ShopBot website.

For more about the Handibot® Smart Power Tool, visit the Handibot website.

To learn more about VCarve Pro, visit the Vectric website.

Why We Build Our CNC Tools the Way We Build ‘em

At ShopBot, we have been designing and building affordable CNC tools for almost 25 years. ShopBots were the first affordable CNC routers for small manufacturing. Our design choices have been based on our experience manufacturing and using low-cost robotic equipment that is optimized for small and medium production operations. Our leadership and innovation in mechanical components and software has been a key to making CNC technology as widely accessible to all shops as it is today.

The design and construction of our tools is derived from two perspectives:

  1. The importance of mechanical rigidity – A CNC tool does subtractive work. It is a piece of digital manufacturing equipment whose primary feature is shaping components by using a spinning cutter to aggressively remove material – good cutting force and resistance to deflection during cutting is required, as is a smooth and vibration-free motion during the machining process. While pure bulk can be helpful to machining, a CNC tool does not need to be expensive or heavy and immovable to produce fast, smooth cuts and be a great producer.
  2. The importance of control system software – You hear a lot about “smart” when it comes to technology these days, but “smart” means more than just running your CNC tool with a computer. Smart tools take advantage of progress in microcontrollers and programming to enhance the cutting and machining performance of a tool, to move it with intelligence, to monitor its condition, to communicate with operators, and to help make the production process friendlier and more interactive. Smart tools can now interact with humans in increasingly helpful ways. They are versatile, configurable, and programmable, making them adaptable to your workflow and production process. This is what we mean by smart.


A). The Importance of Mechanical Rigidity

Large ShopBots Are Configured On-Site – Our Tables Are Matrix-Bolted

Full-size gantry ShopBots are set-up on-site. You position them where they best fit your shop’s needs and production flow. This versatility means they can be put in areas that have limited access to heavy equipment, in a basement or above the ground floor.

The set-up of our full-size tools involves two steps: 1) assembling the steel and aluminum table; and, 2) placing the gantry on the table. The gantry is shipped fully assembled from our factory. The motors on the Y and Z axes have been mounted, and all wiring and hardware installed. The table goes together in a few hours. After the table is assembled, the gantry, which has been fully configured and adjusted at the factory, is simply placed in position on the rails (with a “team lift”). Note that for a gantry-style CNC tool, the gantry essentially is the tool because almost all the components ride with the gantry. That means that after you put the gantry in place, attach the x-motors, cables, and control box, your tool is complete and ready for action.

Shipping large tools as components is a more manageable and safer method than dealing with a large, bulky, and vulnerable single structure. Going through the set-up process creates an opportunity to develop a good understanding of the machine as you ready it for work. Optionally, if your operation needs to hit the ground running, we can send a technician to your site to set-up the tool and then train your team.

Note: Our smaller tools, the ShopBot Buddy® CNC, which is a mid-size tool, and the ShopBot Desktop CNCs are all shipped fully assembled, ready to be powered-up and put right to work.

The stiffness of the ShopBot gantry table comes from its engineering not from weight. ShopBots are assembled with airframe-style bolt-matrixes for strength. Heaviness in a machine-tool can certainly help reduce vibration, but we make full use of materials, such as extruded aluminum profiles, that naturally dampen vibration. You’ll always find YouTube experts who still believe that heavy, cast, or welded frames are important for machining, but heaviness can be overrated and too often simply compensates for other inadequacies of a machine. The practical problem with “heavy” is that it makes a tool less agile, more limited in the locations in which it can be positioned or moved, more power hungry, more expensive to repair, and less friendly for small shops. Such machines (sometimes referred to as “monuments”) do not fit well with a lean production focus which emphasizes a flexibility based on being able to readily reconfigure production flow and processes for competitiveness. 

Significantly, a bolted table can also be realigned using standard mechanic’s tools after the inevitable shop accidents. We avoid welded joints that can become distorted with time and are difficult to re-square or realign. Sure, truly massive welded or cast tools can be impressive and do have the advantage of bulk, but few low-end, welded, CNC tables are built with the mass, weldment thoroughness, and the attention to alignment required for stability in a factory environment. Be careful not to end up with a tool that is just heavy enough to make it difficult to fit into your production flow and not quite massive enough to prevent it from falling out of alignment. 

 

ShopBot’s Tall Table Sides / A Rigid Gantry Platform

The most identifiable features of a ShopBot gantry tool are its raised table sides. Beginning with the patented architecture of our original ShopBots, our full-size gantry tools have minimized cutter chatter and improved cut quality by reducing the pedestal height of the gantry. This effect is a matter of physics. The taller a gantry pedestal – that is the further the distance from the table rails up to the pivot point on the beam for the Z arm – the greater the instability of the gantry. Of course, we want clearance above the work, but rather than just make the gantry taller, our design solution has been to raise the base for the gantry rails using rigid table sides. This significantly reduces the pendulum “moment,” improves cutting smoothness, and allows faster acceleration and deceleration.

Raised table sides have the second advantage of helping contain the material being machined. This provides operators and observers an extra safety shield of protection from cut material and flying debris (e.g. broken cutters) that might break loose during cutting and machining operations if not contained by the dust collector/guard around the cutter.

Our tall table sides/guards mean that our standard large tools are most conveniently end-loaded (front or back) and are well-suited to natural panel flow through most shops. A suggestion: If you expect that you will be primarily side-loading large sheets, whatever brand CNC you purchase, you may want to consider an extended bed so that the gantry can be parked beyond the length of the material to permit easy side-loading without the obstruction of a gantry in the work area.

 

ShopBot’s Beam Extrusions

We engineered the main beam on our gantry tools especially for our CNC tools. Our beams are thickly webbed aluminum extrusions with a strengthening and vibration-absorbing cross-section. They are available for tools having up to a 9 ft. wide cutting area. A mounting face for the linear rails is thickened in the extrusion and then precisely machined and fitted with rails and bearings. As with other elements of our table, this beam is designed to be matrix-bolted to the gantry’s steel end-plates. The beam carries the steel Y-axis car on which the vertical Z-axis, fitted with a router or spindle, is mounted. Each axis moves on a heavy-duty linear rail and bearing system. A sturdy beam is the heart of CNC routers and it is where smooth, precise cutting begins.

 

Drive Mechanisms Choices: Rack-and-Pinion, Screw-Drives

We utilize rack-and-pinion mechanical drive on gantry-tools and screw-drive on desktop tools. We’ve had a lot of experience with various types of motion components for CNC tools and fit the best solution for the needs and purposes of each type of tool we produce.

Our desktop uses Teflon-coated, precision lead-screws with anti-backlash nuts. The screws are integral to the motors which virtually eliminates all backlash. On the desktops, the lower screw and rails are fully covered and protected from dust and debris. This integral screw-drive provides a very high resolution for our desktop machines.

For larger tools, we have found that rack-and-pinion provides the most straightforward and reliable drive system. Rack-and-pinion is highly impervious to the dust and debris of a shop and does not require precise alignment to prevent binding. The modern geometry for grinding rack-and-pinion gearing insures smooth action with limited friction and low backlash. Components can be easily replaced if they become worn. We rarely see significant wear on the rack, but pinions do wear, so you can expect to replace them every year or two during normal use.

The debate over the motion mechanism for CNC routers – rack-and-pinion drive vs. screw drive – can get hot and heavy. We think both systems are pretty good, and over the years we’ve built tools employing each. In theory, ball screws offer the advantage of being virtually friction-free and very smooth. However, they are also more complex. They require a constant precise alignment to avoid binding and are very vulnerable to being disabled by dust and debris, so they must be kept very clean. As the length of an axis gets longer, increasing stiffness in the ball screw is required to prevent the screw from wobbling. This results in large, heavy, and expensive screws (which, in turn, require larger motors just to get them up to speed) that must be well-protected from dust.

Perhaps one factor to keep in mind with respect to CNC mechanicals is that these industrial components have been used as motion components of machine tools and automation equipment for the last 150 years – they are not, recently-evolved mechanisms that are unique to CNC. Over those 150 years, the quality and performance of each type of mechanical drive has been perfected. Gearing design and manufacturing have become highly refined as have the various screw-drive mechanisms for producing smooth motion. Look at a few $100,000 and up CNC tools. In these tools the drive mechanism is only a small part of the overall cost, so the drive decisions have been made primarily with respect to performance. You’ll note that in these tools both types of drive system are used. Sometimes in the same tools screw drives are used for one axis and rack-and-pinion for another. The bottom line is that either mechanism can produce good performance.

We have recently completed an experimental analysis and tests of drive mechanisms that specifically included assessment of helical gearing, a refinement of standard rack-and-pinion. We also evaluated the importance of the gearhead or belt-linkage between motor and pinion. Helical gearing represents a conceptual improvement over straight rack as it produces a more continuous engagement of gear teeth and, in theory, less backlash. We were optimistic about the potential for helical gears, but in our testing, we found that helical gearing added little improvement to cut quality, particularly in comparison to other factors. Our tests actually identified backlash in the linkage between motor and effector (that is, between motor and pinion for rack-and-pinion drives; between motor and ball-screw in a ball screw system) to be the primary source of backlash and the primary determinant of cut quality. For us, this emphasized that the focus for smooth cutting should be the reduction of backlash in the gearing of the motor linkage rather than the specific type of rack-and-pinion. For gantry ShopBot tools, we improve the standard spur gear linkage between motor and effector by using tapered-hob gearheads on all tools (see image below). These gearheads put the emphasis on reducing the backlash that directly results in smoother cutting.

 

Open-Loop AND Closed-Loop Motors and Servos

The cutting motion of ShopBots is powered by stepper motors. Steppers are an incredibly precise form of motor that have the unique feature of never producing incremental errors. A stepper is just as accurate at 80″ as it is at 8” because the rotary position of the motor shaft is just as accurate after dozens of turns as it is after one turn. Stepper motors are inherently digital and thus they are a perfect match to digital computers, digital control, and digital cutting.

Conventional open-loop stepper motors such as those employed on our PRSstandard tools and our Desktop tools are the most affordable solution to producing CNC motion. The counterintuitive feature of stepper motors is that the faster they go, the less power they have. This means that they have the limitation that they can be overpowered if one attempts to cut too fast – losing track of location in the process. However, when used appropriately, these motors will produce excellent cuts, day-in, day-out as they do in a wide range of devices from printers, to CNC mills, to medical equipment.

For heavy-duty, production work we recommend our PRSalpha tools. These tools use closed-loop stepper motors and high-performance hybrid drives. These closed-loop motors have sensors (called encoders or resolvers) that continuously monitor performance and the precise location of the motor shaft. When forces on these motors increase, or if the shaft is pushed slightly from intended position, the motors instantly increase force and recover to the correct position. Servo motors also have built-in feedback and are commonly used in CNC tools. They can be a good solution for CNC, but we favor the closed-loop alpha-step motors because of the hybrid technology combining crisp digital control in stepper mode for small moves while responding with servo-like dynamics when higher power, speeds, or position compensation are required. Undersized servo motors may not provide the speed, power, or acceleration you expect. Our PRSalpha CNC routers can travel at 1800ipm and have 150-250 pounds of cutting force.

MORE INFO … Learn about alphaStep OM Motors

On our gantry tools, we have exclusively used motors built by the Japanese manufacturer Oriental Motor (OM). OM is an international company that has been building high-quality motors for more than a hundred years. Their industry-leading technology has been much imitated, it’s easy to find budget motors that have been made to look like OM products. The copies often fail to live up to the OM performance, which depends on extremely high-grade bearings, precisely cut armatures, dense magnets and carefully wound coils. ShopBot has used OM motors on our gantry tools for over 20 years, shipping almost 40,000 of them. During this period, we’ve had fewer than 6 failures, which means these motors can be counted on for day-in, day-out production – absolutely.

When you are considering the bulk and power features of a tool, do watch out for the macho-power and capital-cost game; it is easy to get ratcheted-up into a large capital layout trap in the form of a leased tool that you need to constantly feed with work, just to make those lease payments. As one of our customers recently noted: “You have to wonder about a tool when they start quoting you an hourly lease cost.” The new industrial revolution is about technologically empowering tools that are becoming available to all sizes and nature of production facilities with prices that are going down – this trend of decreasing tool price has been expressed as a “democratizing of the tools of production.” While new technology tools will cost something, they are becoming increasingly accessible to all shops. Make sure you can afford your new tool.

 

Our Design Philosophy: Iterate and Iterate Again

We are continuously evolving the capabilities and functionality of our tools. We occasionally introduce new models, but our policy is to, as much as possible, evolve our tools as opportunities arise with small iterative improvements that we can introduce immediately and make available to older tools. For example, we currently offer new versions of our Z-axis that is backwards compatible for tools up to 16 years old. Also, as we create new accessories for tools, we focus on making them usable on all tools. This is the advantage of building the equipment ourselves and not to be dependent on changing shipping parts from overseas, or on a gallery of changing designs that depend on what vendor is offering the best export deal. We work to avoid putting you in an obsolescence loop – we always have parts for older tools, and we frequently have upgrade parts that will improve performance.

 

B). The Importance of Control System Software

Smooth and Easy Motion Software

In the 1990’s, the first ShopBots took advantage of the emerging personal computer (PC). PC’s allowed us to make CNC technology more accessible and affordable. Our early tools made use of the new devices to control the tools, rather than relying on expensive, electronic motion boards for control. This means that from our origins, we have integrated the creation and development of control system electronics and control software with the mechanical aspects of CNC tools. We appreciate that good tools start with good mechanicals, but over the years of producing and using CNC tools we have come to a strong belief that software control systems are equally important. In the beginning, software was a focus for us in helping get the costs of equipment down, but as our products developed, our focus shifted to control system software and that provides both smooth efficient cutting and ease-of-use in production.

This means that the hardware and software systems that run our tools are tightly integrated with our tools because they were designed for the tools. Our recognition of the importance of software distinguishes us as the only manufacturer of affordable CNC tools that produces its own controls and software.

 

Software for Smooth, Efficient Cutting

Our software provides smooth cutting motion and crisp acceleration. We have focused on getting high-resolution, straight line and complex curved motion that is chatter-free with crisp accelerations and decelerations to make cutting efficient. ShopBot’s feed rates, speeds, and accelerations are fully adjustable in the tool’s software interface and from within toolpath files.

 

Software for Ease-of-Production

ShopBot’s software interface is straightforward and intuitive to use. Carrying out basic tasks and house-keeping functions such as homing is intuitive. The control software runs toolpath files (part files) generated from virtually any CAD/CAM program. It can utilize files in standard g-code format (Fanuc/NIST RS274) and well as toolpath files that have been created in OpenSBP, an open-syntax CNC language (supported by most current CAD/CAM software). OpenSBP is a “conversational” and programmable language developed by ShopBot and contributed to the public domain.

Thus, you are able to run ShopBots with two different types of CNC files. Traditional g-code is fine for just running files output by CAD/CAM programs. It may feel particularly friendly if you are a CNC operator experienced with other tools, but g-code is an old format that was optimized to be read from early paper tape input devices. It’s awkwardness and illegibility are no longer necessary for digital efficiency. ShopBot’s OpenSBP option provides a second and more ‘conversational’ language that is easy for a human to read, understand, and use. Unlike g-code, OpenSBP includes built-in programming functions (such as variables, logic testing, and looping) that make it readily programmed using friendly, BASIC-language-like expressions. OpenSBP makes it straightforward to do everything from creating a button for moving a tool to a position you frequently want it to go, to creating special production routines that will improve the efficiency of workers as they manage jobs and files and move parts through your production process.

Programmability and configurability make ShopBots easy to set up for even highly specialized jobs, and they can be readily reconfigured for the next job, a day or a month later. Truly interactive digital tools with interfaces that are congenial to production line functionality and automation are what makes a tool helpful and efficient beyond just getting a part cut. It’s what makes a tool ‘smart.’ Don’t assume that because an imported tool calls itself smart, it has any of this flexible configurability or programmability.

 

Software That Is Available and Up-to-Date

As with hardware, we continuously evolve our control systems and software as opportunities to add capabilities and features as they become available. The most recent software for your tool is always available for download from our website, FREE. When the availability of new electronics allows us to develop improved controllers, we also make them available for older ShopBots. It is possible to retrofit our latest control cards or control box – greatly improving the functionality of a tool – to virtually any age ShopBot.

MORE INFO … see how one large cabinet making operation makes use of ShopBot programmability

Coming Soon: Our new FabMo software (short for FABrication and MOtion control platform; currently available on Desktop Tools and Handibots) is our next generation digital fabrication software. FabMo software make use of advanced “S” shaped curvilinear profiles for accelerations and decelerations. These profiles provide smoother action than the trapezoid-shaped, linear acceleration profiles found on most CNC tools. Our profiles are optimized to reduce “jerk” (jerk is a technical term for the 3rd derivative of speed; it is a measurable type of disruption of motion). Jerks cause bumps in cut edges. When they are not managed carefully, they limit how fast a tool can work and contribute to chatter in cutting. ShopBot’s profiles are specifically oriented to reduction of jerk for given acceleration rates and feed speeds. This means our tools work faster, more efficiently, and with smoother cutting – all without adding weight or cost. FabMo software includes an improved environment for creating custom production solutions and for new ways to monitor and interact with tools. FabMo software will be unique to ShopBots as we make it available on all our tools in the coming year.

 

And, We’re Here to Help, Whether You Purchase a ShopBot or Not

For almost 25 years, ShopBot has been developing and manufacturing CNC tools for use in small manufacturing and by individuals. We believe that digital fabrication is the key to making small manufacturing in our communities competitive again. We believe that digital manufacturing is how we can again do competitive, realistic and fulfilling production.

MORE INFO … see essays, written by our CEO, Ted Hall, on reviving small manufacturing

We pioneered affordable CNC. It’s no surprise that we have more competitors today than 25 years ago, when we were the only manufacturer providing digitally-controlled routers appropriate for the needs of small manufacturing. We are frequently asked how we feel about companies that have recently adopted our approach and are now offering affordable technology tools. Well, actually … we feel good.

Of course, we’re flattered, but there is more because we believe that digital fabrication is the single most important key to returning manufacturing. Increasing the availability of affordable CNC technology will help promote local manufacturing and bring more work for all of us. Additionally, some of our competitors offer mechanical approaches not available from us – tools that differ because of design choices with respect to one or another of the options described here. As we note, many of the options are equally good, or offer different sets of trade-offs that may be right for some shops. We won’t hold it against you if you choose another tool. What we want to do is encourage you to continue to use the amazing resources of our website, our free interactive web training, and our user forums. There is a tremendous amount of how-to information of general CNC interest available to you from our site.

And you can always give us a call to talk over any question you may have about CNC.