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Dwayne Cook
11-12-2007, 11:54 AM
Hi SMC

I have a company CNC routing some 1/8th in plywood for me and we have been having trouble with keeping it sucked down to the table.

they have a KOMO machine with a table about 5x10 feet they are CNCing
it for me and then I laser engrave it. I guess with such thin Material and the way it warps cutting small stuff is hard.

If anyone has some advise please tell me. there giving me a good piece price and I feel if its too much for them they wont keep doing my orders.

Dwayne Cook
Epilog 45w & 35w

Mitchell Andrus
11-12-2007, 1:12 PM
Any reason you're not cutting this with the laser yourself?

Perhaps you could make a 3/4" plywood shett to place on top of their table that could make more specific use of the vacuum they're already generating... more, smaller holes in just the right places.

Doug Griffith
11-12-2007, 1:48 PM
I've worked with a CNC hooked up to a vacuum pump the size of a 55 gallon drum and without good fixturing, small parts still move. A fixture made from low density MDF with strategic hole placement and noeprene gasket material may do the job.

Cheers

Michael Kowalczyk
11-12-2007, 4:35 PM
Hello and welcome to the Creek Dwayne,

It may depend on how small the parts are and what size bit they are using. I would probably use tabs/bridges. Depending on the size of the part would determine the number of tabs. When done right they can take the whole sheet off and give it to you intact and you can just use an exacto type knife to trim them out and a small sanding wheel to clean them up. They will look kinda like the plastic models many of us built as kids and some as adults.

What type 1/8" ply are you using. The 3mm Russian birch I use lays flat especially with a vac on it. If they are using the Chinese birch I have heard it called "potato chip" because of the way it warps so easily. I have not had personal experience with the 1/8"/3mm Chinese but have been given sample sheets of 12mm(1/2") and it was warped right from the start. It did have a real nice face though and it was sanded smooth but the poplar core is too moist for my use.

If all the parts are the same or the sheet layout is the same a dedicated
spoilboard would probably be cost effective depending on the size of the run. If it is a small run(only a few sheets) it would probably be cost prohibitive unless you paid for the spoilboards and ran a few hundred parts on a regular basis.

Why don't you cut it yourself on your lasers? I would think 45watt should be plenty fast. About the only thing that I cut on the CNC first before lasering is 1/2" Solid Surface because it is faster on the CNC but only when doing med to large runs.

If you are not set up to cut the sheets and that is what is stopping you from doing it all in house make sure you "Opt-in" to the Freestuff above. It may be what you need. Hope this helps...

Dwayne Cook
11-13-2007, 2:05 AM
thanks for your Help.

I am having them cutt about 5000 pieces so i was thinking that would take forever on my 45w Laser... and I guess I am inexperienced on the vector side of my laser. I work with vector and raster art but I raster everything I do... so far. I am always looking for info on vectoring I.E. speed, Power, Freq.,... I deal with speed and power on the raster but not the freq.

so I digress... I need to learn more but my lasers.

Dwayne Cook
Epilog 45 &35

Sandra Force
11-13-2007, 7:40 PM
I would cut it to fit in my laser and vector cut it myself. It will cut that thickness fairly fast. :o If you go to the Epilog web site and their tech support tab you will find a large # of tutorials that will help you. I don't run Epilogs any more and still find their information handy. You may need to experiment a little to get the exact speed and power combination that works best for you. Once you have found it you will wonder what the worry was about.