Holding down Styrene sheets

[gerraldpeters]

Plastic experts help needed.

I have a DIY FLA CNC machine and works well. I made a vacuum box from MDF and sealed all sides but the top. Using a shop vac to suck vacuum. It seems to hold down my Styrene sheets (0.040') but when cutting the parts I loose vacuum. My question is what would you recommend to hold down the sheets as the vacuum system does not seem to work. I am using a upcut bit. Afraid that when using a downcut I get chips under the sheet and then also lift the sheet.

Would love to hear from all of you!
Thank you!

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[awerby]

I doubt your shop vac is strong enough to provide vacuum pressure sufficient to hold down your parts; it's good for cleaning up chips, though. Look for a real high-volume low-pressure vacuum pump. Usually these are single-stage rotary vane type pumps. Size it to be in scale with the size of your vacuum pod.

[gerraldpeters]

Thank you very much for your reply.

What would you consider a good size pump. My box is 20"x24"

[beone]

Subdivide your box into multiple compartments. As you cut thru and lose vac shut off that compartment so the others still have vac and hold the sheet
Dave

[gerraldpeters]

That is an other great idea. Thanks beone

[xjdubber]

If your wanting to do this cheaply..... what 1 shopvac wont hold down 2 or 4 might hold down. I think there is even someone out there that sells a setup with 4 vacuum/shopvac motors for this purpose.