Fixture Setups for CNC Machines

Hey CD! Team 1058 up here in NH just got our very own Bridgeport VMC760 that we’re starting to use for most of our manufacturing. For teams with similar enclosed machines, what do you use for fixturing? We’re looking at dual-vices but that takes up most of the bed space and means we’d have to take them off for plate work, and re-tram each time. Do any teams have custom fixtures that make 1x2 extrusion work faster and are a bit smaller?

I have just been working on a fixture for our Tormach. Using some removable Mitee-Bite clamps, can be used for 1" and 2" extrusions. I haven’t built this yet - waiting for clamps and stock to come in. But this should help us save some time this year.
fixture-1

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Looks pretty nice! Whats the black objects in between the rails? What clamps are you using, can you send a link? One concern I had was that clamps like that are only grabbing the bottom, what prevents it from tipping or not being vertical during high loading? We experience this with our current approach when cutting 1x2 with the 1" face at the top

I have done this in the past:

Create a large flat fixture that clamps in the vice, with a table on top. Then bolt down a spoiler board to that flat fixture, then you can screw in or clamp your flat sheet to that and cut it.

We used a 4"x2"x18" (Vise-Vise) extruded aluminum tube and welded a .375" aluminum plate onto it. We clamped that on the the vise and faced it with the mill (so that it is perfectly flat to the mill) and drilled through holes for bolts. Then we bolted a .5" MDF board on to that for a spoiler. Then we used that as the table for a large flat part we had to make.

It wasn’t the most rigid setup, so we couldn’t wale on it at 200ipm, but we were surprised to see it work so well.

This was for my work at a machine shop. I don’t have any pictures, however.

Just imagine NYCCNC’s fixture plate welded on to a pipe that the vise held.

Funny that I was in the process of designing something very similar. I decided since these clamps (especially the mitee-bites) were expensive that I would instead move the stop. I really began not to like the double clamps because they clamped on the center of the 1" side of the tubing which would likely deform and round the tubing, especially on thin walled pieces.

To counter that I designed this which has the same adjustable stop but uses the mitee-bites alone. Since they are gripping where there is full width of material I’m hoping it would cause less deformation. Another option is just drilling and tapping more holes in the plate. Works with 1" and 2" stock, but could easily be modified to accommodate larger pieces as well.

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The black objects are the center part of the Mitee-Bite Uniforce clamps. The hex clamps further out are these guys.
My main use is for doing 2 pieces at once, not holding one at a time. I have yet to go back and add a position for the hex clamps in the center for holding one piece, but I could also simply put a second piece I’m not cutting in the other side as a blank for equal force.

For our Tormach we use SMW’s Fixture plate along with their Mod Vises. The mod vises are great for clamping parts and plates of all sizes (since you can use multiple of them to clamp a large piece of stock or plate, or just 1 for a smaller part), and saves a lot of time during setup.

We also made a subplate for various other holders/accessories, like a 3 jaw chuck, our 4th axis, and the standard tormach vises that screw right into the fixture plate. Those subplates make setup time basically non existent, because you can be sure that your vise or 4th axis or etc etc, is always perfectly inline with ur axes as soon as you bolt it down since you squared the fixture plate when you first installed it.

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what if you made some nice plates the max size of the vices. Then you can use those to mount down an aluminum plate to the top of the vices that you can put your spoil board and sheet stock on? would you have enough z clearance for that?

We did exactly that last year for the majority of our parts. Custom fixture plates saved us a lot of time not zeroing each piece, and makes manufacturing spares and repeated runs much faster since you just swap out a blank. I am actually aiming to get some information out about how we did our custom fixturing in the next couple of weeks, as this is something teams can benefit from, but may not know where to start.