# Workholding



## thuston (Jun 11, 2010)

I have a 6' x 10' table which has adjustable vacuum ports which I can close off for whatever size of material I need to hold by using gasket material and table plugs. The vacuum works quite well with full sheets of material or moderate size parts after the machining. What the problem is that I'm having issues with smaller parts or pieces that have most of the material cut out of the them which in return doesn't allow much surface area for a good seal on the MDF Spoil board. Does anyone have any ideas on how I can improve my workholding issues to hold smaller parts without the use of fixturing? I've thought of maybe using a thinner piece of material under the actual sheets I need to cut out of and pocketing the dimensions of the piece I need to make, only smaller than the actual size. So that everything would be sealed off and the vacuum isolated to the actual piece. This method I think would add so much more setup time and would only be good for that piece, where I would need multpile sheets of material just like fixturing. The way I do it now is I don't machine down to the spoil board maybe leave around .010" then hand deburr the remaining material off, which works great except when you have a 1000pcs this gets pretty monotinous. Anybody have any ideas how I can solve this problem?


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## Phil P (Jul 25, 2010)

Try a combination of techniques. By combining component nesting with onion skinning you will get pretty near to the end result (and I'd go to between 0.1 and 0.2mm to leave a paper thin skin), but you need to add some self adhesive tape between the spoilboard and the workpiece (All Star Jig Tape?) when you load the machine. After the main cutting has been done make a final, breakthrough pass. That final pass should break through the bottom of the material but only just crease the tape and needs to be done at an extremely slow feed speed with the tool path designed to sweep out away from the workpiece at the end of the cut. It will mean resurfacing the spoilboard regularly (daily or more frequently), especially if you happen to live in a place with changeable weather. I've done this before on ABS components, but to be honest with many products where I was going to do further edge treatment (like sanding, etc) I found it easier to flip over the work piece and break out the components with a one hand router like the Festool OF1010. After all 1,000 components isn't really that many

BTW I'm assuming that you draw through something like a piece of lightweight MDF spoilboard with all the edges properly sealed and made to the minimum posible dimensions.

Regards

Phil


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