Sheetmetal workholding on a mill?

[InspirationTool]

I do alot of stainless and aluminum sheet metal work, mostly 14/12/10 gauge. Usually under 2" x 3" or so.

The production parts are cut by laser or waterjet. Prototype parts are cut on a bandsaw or punch. I'd prefer something more accurate.

I'd like to get a small CNC mill at some point, and could probably make my money back in a couple of years just doing the prototype and small (10-20 parts) production runs of these parts on the mill.

But how would I hold the parts? Some of the parts could be cut in two stages with a vise, but I'd prefer to do it in one shot. And I'd worry about distorting the part.

Double stick tape? Glue that can be dissolved?

Thanks for any hints people can give!

-Jeff

[kbarratt]

I'm stuck doing this because we have no sheet metal shop, or sheet metal tools. I always end up making a subplate with threaded holes, and laying out my work around screws to hold down the sheet. Some times I can stack sheets, but it usually produces a number of bad parts if the sheets aren't clamped down evenly. A thicker piece of material on the top can help support it as a type of stripper plate, and provide better surface contact for clamping, but the depth of cut can be a limitation if your stacked too high, due to the length of the end mill.
I hope someone gives you a better idea so I can use it too. The subplate method is very time consuming.

[70cyclone]

vacuum table and stripper plates

[JWOOD]

I tend to have to do alot of sheetmetal parts and mods. at work. Whenever I can I use a vaccum chuck. However I do frequently use double sided tape, the trick is to use good quality carpet tape, the stuff I use has a cloth in it just like duct tape. Just do not use any coolant or the tape comes loose. The tape works great for aluminum, pcb's and plastics. Remember to go easy and it'll be fine. On pcb's typically run 8,000rpm at 350-500mm/min with a .5mm depth of cut using an 1/8" carbide endmill.

Thier is also a heat activated sheet adhesive from Mitee-bite but I only used it once and found the tape much cheaper.