Originally Posted by
MARV
Canman77,
This is where guessing and supposition comes in (read trial and error). If you were using a new surfaced spoilboard and could verify that your work piece was equally flat and pulled down well to it, then its reasonable to believe that your spoilboard would "backup" your part and prevent blowout. Much of this goes down the drain, however, as soon as you cut a different part. This why any well oiled cnc program within a commercial/industrial shop will have a fair understanding of the range of their workpiece requirements and try to fashion generic solutions to accommodate.
Vacuum work holding can be a maddening endeavor. Much of it can be overcome by knowing the fundamentals, thinking about the part in hand and applying a little and error. What is challenging for many guys on this forum is they want it to work for the one part they're going to cut today. Tomorrow, the part in hand is completely different.
Stay with it. I think what attracts most people here is learning and making stuff and vacuum work holding is a component of that.