Holding Small Cut-Outs in Place

Tiny cut-out pieces created when profiling CNC grill-work can pop out, land on the panel, and cause trouble. Here are some tips on keeping those small pieces in place or controlling where they end up. June 30, 2007

We machine a lot of decorative grilles on our flat table Buselato. These panels have lots of small cut-outs in them. The problem is that many of the waste pieces (the center of a circular cut-out) will come out of the hole, and if it does not get picked up by the dust collector, it lays on top of the panel.

We have had a couple of times when the router will move to the next cut-out and set-mill down on top of one of these small pieces. That has almost started a fire as the small piece starts spinning against the main panel.

We have applied packing tape to the back side of the panels to keep the small parts in place and that helps. But covering a 36" wide panel with 3" wide tape is a pain. Has anyone had luck with any other method of dealing with this?

How about a source for really wide tape? I'm thinking of something like the peel coat that comes on glossy P-lam. Yes, it would be better if the pieces stayed put, but I'm talking about sometimes 60 - 70 small 2" diameter pieces.

Forum Responses
(CNC Forum)
From contributor G:
We cut the small pieces as an "island fill". It starts at the center and works its way to the edge. Turn it into chips and there won't be anything to bounce around.

From the original questioner:
I should have included in my post that I would rather not pocket all the cut-outs. As it is, some of the panels are on the router for 1 hour now, and many of the cut-outs are odd shaped.

From contributor J:
Have you considered placing tags at strategic points on your tool path in the programming? I will do this if I don't turn it to dust. But a lot of times I actually need the small part, so to keep it from moving I will put tags on two sides that are 1/2" long and 1/16" thick, so when I am finished I can snap or sand off the tags.

From contributor E:
One thing you could try is to either use thin tabs like contributor J suggested, or leave a skin under the small cut-outs and run the piece upside down through the time-saver afterward (allow a little extra thickness for the sanding). If you leave a little space at the out-feed of the time-saver, the little pieces will drop off the conveyor into a box where you can recycle them into toys or throw them away.

From the original questioner:
More information. The cut-outs are profiled on both sides. We cut halfway through from one side with a combination round-over straight bit. Flip the panel, then cut from the back side the rest of the way. It works great except for the pieces. Again, some of the panels have upwards of 200 cut-outs in them.

From contributor G:
Vinyl sign makers use a wide tape 12"-36" (?) material so they can peel the paper off of the sticky letters and have them stay in place. Then they lay the letters sticky side down, burnish them and pull off the carrier sheet. I don't think this will help hold the pieces down too well all the time.

We have done two-sided detail on our stuff and try to have the point cutting roundover finish the small piece and leave a little fuzz to keep it more or less in place, then finish with a sanding mop.

From contributor J:
The tagging/onion skin method could still work. Just apply the same method to the middle of your part thickness. I have also had to do this. Adjust your tool depth to accommodate 1/16" thickness in the middle. For the time you will save not having to tape your parts, you can spend less time sanding the edges.

From contributor K:
If you add copper tubing to an air nozzle, the operator should be able to blow the pieces out of harm's way before the cutter comes back down. We do this all the time; works fine.

From contributor S:
Contributor K beat me to it... blow them away. You could even rig a nozzle to your hood with a regulator so your operator won't have to stand there for an hour.

From contributor P:
We use Camie adhesive spray. Lightly coat the underside prior to setting piece to table. Minor clean up if any at all.