View Full Version : Preventing Wood Burn?

Gary Berman
11-02-2013, 11:36 PM
I am doing a fair amount of plywood cutting on a 60w Epilog CO2 laser. The bottom face of the wood, the part sitting on the honeycomb, ends up with charring along the cut.

I recently heard of people putting some form of adhesive on that face to avoid the wood being burned there. Is anyone here familiar with that? Is there some special kind or will masking tape or blue painter's tape work (I have a lot of that around right now).

Thanks for the help!


Rodne Gold
11-03-2013, 1:46 AM
Tape wont prevent the charring , what might is if your laser has a setting for ppi (pulses per inch) when in vector mode. Reduce this to lower levels. Essentially you are cutting by drilling a series of holes close together - your holes might be too close together , putting a lot of heat into the material, so reducing the pules spaces them apart , but still overlaps them to get a continuous cut , but less heat.

Michael Hunter
11-03-2013, 7:28 AM
Masking tape will certainly help by reducing (maybe eliminating) flashback "ticks" and smoke marks caused by the honeycomb.
I use transfer tape, but any sort of masking tape will do*

If the bottom of the cut is really charred, then follow Rodney's advice to get the cleanest possible cut.

* I got some very cheap masking tape recently - the glue is heat sensitive and makes a mess if it gets even a bit warm.
This stuff now reserved for other tasks.

Dewey Schramm
11-03-2013, 7:41 PM
I hate to be the person who states the obvious - but one other cause of burning/scorching on the bottom could be soot buildup on your honeycomb. It may be time to clean that as well.

Jerome Stanek
11-03-2013, 7:57 PM
I just got my laser and had a job to cut some plexi when I placed it on the honeycomb I was getting small flash back burns from the honeycomb so I made a jig up out of corian with a .25 wide by .25 deep route on the cut line with son relief cuts to evacuate the heat and smoke. It gives me nice clean cuts and solves the problem of registering my parts. I only had .125 material around the edges of the blanks

John Bion
11-04-2013, 1:44 AM
In addition to what others have said, Air, Air and plenty more Air directly into the cut line. I have no idea what the compressors on the Epilogs are like, but I run a large industrial compressor for my machines cutting plywood.

Mike Lysov
11-04-2013, 2:21 AM
Just raise plywood from your honeycomb and you won't get any reflection/burns at the back.

3-5mm spacing between material and the table is more than enough.
You can find something that will act as pins to raise it.
I use screwdriver heads as pins. Their bottoms are about the size of my honeycomb table cells so they sit tight and keep material raised.

And make sure the table is not too dirty. If it is you will get reflections at the back even if it is raised.

walter hofmann
11-04-2013, 4:58 AM
I use 5mm stainless rods as lift up it works perfect and for cleaning I did find out that wipes from the Swiffer works amazing

Gary Berman
11-04-2013, 9:08 AM
Thanks much to all for the advice. I'll try cleaning the honeycomb. I'm using shared lasers at a shop and I'm not sure how often they are cleaned. Raising the boards is a little dicey as they are often not quite flat and we need to weigh them down. And, we're cutting out fairly big pieces which, if not supported properly, may pull or separate before the cut finishes.

A service bureau working on a similar job uses transfer tape, like Michael does. Can anyone recommend some? The shop has drilled in lots of concerns about using laser safe materials. Looking online, I see lots of different kinds.

Thanks again!!

Michael Hunter
11-04-2013, 9:41 AM
Transfer tape -

The type you want is paper-based and looks just like thin masking tape.
There are lots of makes and they all seem much of a muchness (little to choose between them).
(Don't get the plastic film types, which are probably vinyl).

Available from most suppliers in low, medium and high tack.

High tack means what it says - difficult to get off again.

Medium tack is probably the best for unfinished wood. Apply an hour or so before cutting if possible.

Low tack tends to fall off untreated wood (though it is fine for varnished wood, plastics etc. with smooth surfaces).
Note that loose tape is a serious fire risk!

Chuck Stone
11-04-2013, 12:14 PM
Low tack tends to fall off untreated wood (though it is fine for varnished wood, plastics etc. with smooth surfaces).
Note that loose tape is a serious fire risk!

If Low Tack is all you have, you can still use it on untreated wood if you work it in with a steel
brush. (like a miniature version of a BBQ grill brush) I forget where i got mine, maybe the
hardware store, not sure. But you work the tape in with the brush all the way out to the edges
and it holds pretty well after that. You'd think the steel brush would tear the tape apart, but
it really doesn't. (yeah, it surprised me too)

Mine says "Workforce" on it .. sounds like a brand name for Home Despot or Lowes

Michael Kowalczyk
11-05-2013, 1:24 AM
maybe your material can be a contributing part of the problem..Exterior glue can be a problem