Question About Holding Down Kydex Cutting Through W/Upspiral

[Josh B]

Hello,

I was kind of thrown into learning how to use the Axiom Pro Plus (I believe, it's 24x48") at my job. I jumped into VCarve and with the help of some tutorials I figured out how to do the basics of what I needed, cutting Kydex Sheets into panels to hold military pouches on. After lots of hard lessons learned I've gotten this aspect down pretty well, and have started dabbling in other projects with the CNC. The biggest problem I still can't figure out is a good way to hold down the 24 x 48 sheet of kydex when cutting larger sized panels (22x30). As of right now I'm using a 3/4" MDF frame that barely holds the outside edges of the kydex down on top of spoilboard, and I have markings on the frame to check the max and min X,Y in all 4 corners to make sure everything is lined up. This is incredibly time consuming, prone to slight error, and I still get really bad pull up in the middle of the sheet as I am cutting with a 3/16 upspiral bit. It's a long shot but has anyone dealt with projects like this and have any suggestions. Sorry for wasting anyone's time just figured I'd take a shot. I'm new to this forum and not sure how to attach pictures but I can send one if anyone has any suggestions.

TIA

[loren]

This seems like a perfect application for a vacuum table.

[johnb]

I read somewhere that a right hand cut bit with a left hand spiral (downcut) is good for Kydex & that kind of plastic since it pushes down instead of pulling up. Check with Quinco

[Josh B]

I've reached out to Quinco, thank you. I thought about getting a vacuum table but I don't know how that would work with a spoil board as I am cutting all the way through the kydex.

[johnb]

Josh B

You need to read up on some of Gary Campbell's (most excellent) thoughts on vacuum tables. The gist of it all is that mdf, unless sealed, is porous and even a modestly powered shop vac can pull a vacuum through an mdf spoilboard. Basically, you build a "box", seal up everything except the top and bottom of the spoilboard (which you have previously flycut to eliminate the "glaze"), apply suction to the plenum (the box) and suck down your work piece. You don't need holes in the spoilboard. The grooves in the spoilboard from through cutting don't matter (provided they are within the outer perimeter of the "next piece" that you're going to hold down.) There are several threads here on vacuum tables.

[Josh B]

Wow that is really helpful that sounds like exactly what I need.

Thanks!