By Sallye Coyle, October 16th, 2019

 

This blog post originally appeared on the 100k Garages blog in 2017. I often get requests for information regarding two-sided machining on a ShopBot tool and figured with that many people asking about it, that we should cross-post it here on the ShopBot blog for additional accessibility. I have edited a few things to account for updates in later versions of the Vectric software. 

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A good friend recently sent me a Solidworks file, and asked about machining it on a ShopBot. I don’t have Solidworks on my computer, so I requested and received the model as an “.stl” file. The model could have just as easily been created in Inventor, Rhino, Fusion 360, or any other 3D rendering software/scanner.

Since I do have Aspire CAD/CAM software (VCarve Pro’s big sister software), I imported the .stl (component or 3D model) twice (inside and outside) so I could plan my strategy. I originally wrote this blog using VCarve Pro v. 8.0, which was fully capable of doing all the machining. Vectric software v. 9 and above give you the option of setting up a two-sided file, so that would eliminate some of the steps outlined below.  One caution: With VCarve Pro, you can only import one component at a time. That would work for this application, since the “Inside” and “Outside” of this project need to be treated as separate CAD/CAM files.

The photo below shows the finished result. At the end of this entry, I have indicated how I would charge for a project such as this.

 

 

 

 

 

 

Givens:

 

Thinking Through the Project

Setting Up the File and Materials for Two-sided Machining

 

Prepping for “Inside” Machining (File #2)

 

 

Analyzing the file, observe that some sections need to be created as a 3D (simultaneously moving 3 axes) file. However, much of this side can be machined with 2D toolpaths (plunge the Z and then machine at that depth), which will save time and give better results.

The Big Picture

 

Creating Toolpaths for “Inside”

 

 

3D Toolpaths

Open the Tool Database (Library) and, if necessary, create two .25” ball nose bits. Start with any ball nose bit, Copy it, and change the name and specifics of the new bit to reflect its use:

*These values are good for the gantry tools (wood).

 

2D Toolpaths

 

 

Specify a .25” end mill bit:

Registration Holes and Hold Down

 

 

 

 

 

Simulation of the “Inside.”

 

Prepping for “Outside” Machining (File #3)

 

 

Most of this side needs to be treated as a 3D (simultaneously moving 3 axes) file. Only the final cut out will be a 2D profile-to-the-outside.

The Big Picture

3D Toolpaths

 

 

Specifying a .25” ball nose bit:

 

ShopBot Set Up

Place the Real Board into Position

Running the Files

 

Results

 

These parts were machined on a ShopBot Buddy® (32″ x 24″ cutting area).

 

 

 

 


 

 

Completed samples viewed from the inside and the outside of the seat bracket.

 

The two sides fitted together.

 

**What Would I Do Differently?

Design time: It would have cut down on my design time if I had asked the customer to send the vectors that made up the original 3D model (.eps or .dxf format) in addition to the 3D model itself (.stl format). As it was, I had to use the tool in the Vectric software to define the edge of the component, or redraw the vectors I needed over the 3D component.

Toolpathing options: I would think through more carefully how deep to make the tool paths that go along the edges of the model. If I had made the 2D cut out on the first side I machined shallower (the “Inside”), then I would not have had to create two separate 3D finish passes near the edges of the second side (the “Outside”). I would still put hold down screws in the center of the “Outside” pieces so that the work did not shift when I ran the final profile to cut out the samples.

*** Setting Up the XY Zero Routine

If the automatic XY Zero routine using the proximity switches has not been set up on the ShopBot, now is a good time to do that. In the ShopBot Control software, click on Tools > ShopBot setup. Click through the screens to find the page that talks about setting up the XY Zero routine. Choose “Make it easy on me.”  The program will let you use the keypad control to move the bit to where you want 0,0 to be and zero it there. (Click on the fixed distance button on the keypad to fine tune movements of the ShopBot.) Then, the program will test the distance between the 0,0 point and the proximity switches, and make it so you only have to use C3 or the icon on the position screen to zero the X and Y.

This is critical if you need the 0,0 to be absolutely accurate. By using the automatic X,Y Zero routine to give you a good starting point, then moving the bit to an exact location (M2, 12, 12) and setting the new zero there, you can always get back to that point in case of power failure or operator error.

 

Suggestions: How to Charge for a Project Like This

Although I did not have to create the original model, the expertise to figure out how to machine the model, and the cost of owning, maintaining, and running the shop and equipment to be able to do such a project should be taken into account.

 

Tools in Vectric Software to Help Estimate Job

Compare estimate to realtime.

October 16th, 2019 | Tags: , , , , | Category: Digital Fabrication, Fabrication Techniques, Product Prototyping, ShopBot, ShopBot Sallye

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