Production Case Study: Handibot Smart Tool

Hi, I’m Ryan Patterson, head of Production Support at ShopBot Tools. One important aspect of our company that I think sets us apart is the way we work with people to customize solutions for their production needs, from helping them to choose the right tools or tools, to assisting them with the configuration of tools to meet their changing needs. I’ll be blogging here on a semi-regular basis to share examples of this — starting with this entry that’s “close to home.” It’s the story of how we made some changes to our production method of Handibot Smart Tools here at ShopBot HQ.

While the Handibot was being designed, the production group had a general idea on how we would produce the product.  The prototypes were cut on a PRS Alpha using a large universal vacuum system with a bleeder board.  One Handibot was produced using a third sheet of 4×8 material.  We thought we would scale this up to fill/nest a full 4×8 sheet of parts.  We started cutting the first sheet and the estimated time to finish one sheet was a little over an hour.   We were quickly able to see this would not work.  A universal vacuum system uses a sheet of MDF as a spoil/bleeder. Over the time of cutting the MDF compressed and affected the depth of cuts.  As we started making the final thru-cuts, the vacuum was not holding the parts in place.  At this point we had two options,  stay with the large format system (4×8 machine) with a gasket vacuum or move to a smaller cell based system (using the ShopBot Desktop machines).

We decided to use the smaller Desktop system with fixtures and a high pressure vacuum system.


With a cutting area of 24×18, we would need four different fixtures to have enough parts to produce one Handibot.  Now we had to decide how many desktops we should use.  One thought was to use one for each fixture and this is what we did.  We later scaled back to using two Desktops, as we found that the cutting was not the bottleneck to producing the Handibots.  This scalability was one reason for selecting the Desktop cell based option.  As our efficiency down the line increases, we can quickly add another Desktop.

We are currently using two Desktops with four fixtures.  The vacuum fixtures use a gasket around the inside of the cut with a high pressure low volume vacuum pump.  For this type of vacuum system to work, no thru-cuts can be made inside of the gasketed area. The red lines pictured show the channel for the gasket.

drawingThe fixtures were created using VCarve Pro by importing all the parts for a Handibot, then manually moving and rotating the parts around to fit in a 24 x 18 inch cutting area.  We used vector editing tools to offset geometry around the thru cuts to create the section for the vacuum.  Once the geometry was created, it was offset .25 inches to create a .25 inch wide channel.  This channel was cut .18 deep to fit the gasket of .25 x.25.   We then added holes for mounting and indexing to the table.  After the fixtures were cut we drilled a 1/4″ hole in the edge of the   fixture for a 1/4 tube to be added to the gasketed area.  Then we drilled a horizontal hole to connect with the edge drilled hole.  We then inserted a 1/4″ tube to be connected to the vacuum pump.

Due to the fact we were using two machines with four fixtures, we needed a quick and easy way to index the fixture to be placed in the same spot every time.  The index needed to be the same on both machines being used.  The first step was to mount a sheet of aluminum 3/8 thick x 24 x 18.  The aluminum was then surfaced to insure it to be flat.  The next step was to drill and tap indexing holes into the table.  We added matching thru holes drilled in to the fixtures.  The tapped holes gives us a way to index the fixture and a way to hold the fixture to the table.



pc and dt setup

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