Work Offsets with a Shopbot

Hey All,

We recently acquired a Shopbot PRSalpha thanks to our school, and we’re thinking about setting it up for machining tube extrusion. We ordered some machine vises from Shars Tooling, but we’re wondering how to attach them and tram them in. Would just bolting them to the waste board be a good plan? Also, does anyone have experience with work offsets on a Shopbot? We were thinking about using them for our vise setup.

If you’re using HSMWorks and Mach3 I recently made a 2 part video about using multiple work offsets. You can find that here.

As for the vises, we created a vise jig out of 3"x.5" billet with slots for each vise. The edge of the vise jig is also milled so we will tram that first with a test indicator and then put the first vise in (this one is trammed since the slots are a perfect fit for the vise), then trams the 2nd and 3rd vise using a piece of tube and the test indicator. If you click on the link in my sig there’s a link to some more photos of the vise jig.

Sadly, Shopbot is not compatible with Mach3, but we do run Fusion360 CAM, which is relatively similar to HSMworks. The tramming jig sounds good, we were thinking about putting a piece of versaframe in all of the vises and then tramming the whole unit before bolting it in.

The workoffset method for the g-code in F360 should still be the same then, you’ll just have to figure out how to assign G54-59 with your controller software.

As for the versaframe method, that should work.

We do this, but not with a shopbot.

Our holding fixture is a thick piece of plywood (glued up), screwed down to the spoiler board, into which a 3/4" deep by 2" wide slot was machined by the CNC itself, thus perfectly trammed. We also machined a 1" wide by 1.5" deep slot in case we needed to machine the edge of the 1 x 2 aluminum. The ends are held down by clamps front and rear, and we use the CNC machine to cut the material to length as well.

To allow us to remove and reinstall the fixture we first installed it against the side and front edges, but upon reinstallation it needs a little tweaking to be in tram, partuclarly horizontally.

We use Cut2D software to manage the offsets. Cut2D is available for ShopBot, or at least was at one time.