Holding Down 1/4-Inch Materials on a Vacuum Table

      Thin panels can be hard to hold down, especially at the edges. Here's some advice. September 3, 2010

We recently bought a Panel Pro 145G18CD / 2007. The vacuum pump is a Dekker 40 hp. The table is a 3 zone 5x12. I was cutting out parts and all was well until I started on the 1/4" sheet and noticed the ends would not stick. The material was ply pre-finished one side. Has anyone had a similar experience? I also had a problem with 1/4" melamine MDF core finished two sides. The spoil board was just surfaced and the vacuum pump gauge indicated 24 hgv.

Forum Responses
(CNC Forum)
From contributor D:
Although our vacuum pump isn't as big as yours we too had the same problem. I think it could simply be that the 1/4" material isn't rigid enough to stay flat. Have you tried a down cutter?

From contributor Z:
Have you boys tried flipping the work piece over? Often the thinner material will have a tendency to bow. Face the bow down and the vacuum should suck the panel flat.

From contributor D:
I cut 1/4" material all the time, using a 12hp pump and a homemade spoilboard on a pod and rail CNC. I jumped through a lot of hoops until I finally had it down. It came down to a combination of using Trupan ultra light, 1/4"Onsrud spiral-O single flute downshear bits, and tabbing all small parts. The small parts need to be snapped off after cutting, much like model airplane kits I had as a kid.

I tried many different sized bits, up and down, compression, and combinations of downshear first and upshear for a final pass, with 1 to 3 flutes, hoggers and chipbreakers as well, but with only 12hp, the best performance was 100in/min at 16k with the above spiral-O bit, as the chips crammed into the groove nicely and aided in holding my parts, which in some cases are only 5/8" wide. Some on this forum advocated the use of screws a while back, and that works too, but I don't like the hassle myself.

From contributor K:
When I use tabs I trim the parts out with my trim router and a flush cut bit.

From contributor S:
I had a similar problem with 1/4 inch x grade phenolic. I had to seal the spoilboard with spoilboard tape and added a 60 gallon vacuum rated tank close to the router. Pumped down the tank (24") and opened up the valve. The extra negative volume in the tank snaps the board down fast. It makes the board lay flat. I noticed, however, that the phenolic let air suck into the table. That is probably a factor when cutting faced MDF.

From contributor J:
I have found a lot of people run into this issue due to the speed of cutting the spoil board and the flow they have through it. Remember to check your spoil board without any material on it to see what the difference is. I have found many people read the gage and come up with 14 to 18 hg with no sheet on the spoilboard. This is a problem as it is not getting to your sheet. sacrificial panels should be ran around 30 meters per minute and around 8500 rpm for optimum flow of Vacuum I have found after working on the flat table since the first one came out from Italy. Give it a try you might find a different result.

Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?

Have you reviewed the related Knowledge Base areas below?
  • KnowledgeBase: Knowledge Base

  • KnowledgeBase: Computerization

  • KnowledgeBase: Computerization: CNC Machinery and Techniques

    Would you like to add information to this article? ... Click Here

    If you have a question regarding a Knowledge Base article, your best chance at uncovering an answer is to search the entire Knowledge Base for related articles or to post your question at the appropriate WOODWEB Forum. Before posting your message, be sure to
    review our Forum Guidelines.

    Questions entered in the Knowledge Base Article comment form will not generate responses! A list of WOODWEB Forums can be found at WOODWEB's Site Map.

    When you post your question at the Forum, be sure to include references to the Knowledge Base article that inspired your question. The more information you provide with your question, the better your chances are of receiving responses.

    Return to beginning of article.

    Refer a Friend || Read This Important Information || Site Map || Privacy Policy || Site User Agreement

    Letters, questions or comments? E-Mail us and let us know what you think. Be sure to review our Frequently Asked Questions page.

    Contact us to discuss advertising or to report problems with this site.

    To report a problem, send an e-mail to our Webmaster

    Copyright © 1996-2019 - WOODWEB ® Inc.
    All rights reserved. No part of this publication may be reproduced in any manner without permission of the Editor.
    Review WOODWEB's Copyright Policy.

    The editors, writers, and staff at WOODWEB try to promote safe practices. What is safe for one woodworker under certain conditions may not be safe for others in different circumstances. Readers should undertake the use of materials and methods discussed at WOODWEB after considerate evaluation, and at their own risk.

    WOODWEB, Inc.
    335 Bedell Road
    Montrose, PA 18801

    Contact WOODWEB

  • WOODWEB - the leading resource for professional woodworkers

      Home » Knowledge Base » Knowledge Base Article