I'm working on a personal project , the project is a Catan board game, inspired by the versions on thingverse but 95% newly designed (only used the sheep and ship lol) anyways none of that is important.
When I'm cutting the outline with 1/4" acrylic directly on the honeycomb bed the laser will hit the honeycomb and sometimes ignite the acrylic vapors causing the whole sheet to pop up blowing out some of the smaller already cut parts. I tried raising the honeycomb off of the bed with a few chunks on angle iron thinking it might pop but the pressure would have somewhere to go instead of up and now instead of popping it just ignites and burns causing a smoked appearance on the acrylic. The same thing happened when I turned on the bed vacuum with the honeycomb sitting on the bed. Adjusting power, speed, and air pressure for the cut assist did not help.
Will a nitrogen air assist stop the ignition of the vapors? Google has failed me, I can't find any references to using a nitrogen assist on any sort of plastic. What sort of CFM will I need for a flame polished edge? I know that too high of a CFM will cause a white edge and too low probably would not induce enough nitrogen into the backside of the cut where it is igniting. Will leaving the paper on the backside of the sheet help with the burning or at least minimize the smoked effect? Will raising the acrylic off of the supporting surface help? if so how would I support the entire workpiece with 1/2" support spacing? the smallest pieces are 1" circles and I wouldn't want them to partially fall with an end sticking up to hit the nozzle. I also don't yet know how to order the cuts to start at one edge and work my way across, doing a perimeter cut first could be bad.
Acrylic cutting vapors popping or combusting
Moderator: baker
Re: Acrylic cutting vapors popping or combusting
First of all, when cutting acrylic, using a blade type worktable is much more comfortable. I'm just guessing, but with a honeycomb table the acrylic fumes might get caught between the table and the material sheet, causing mini-explosions. It's not uncommon to ignite either. To prevent that, every laser has a compressed air blower. I really didn't hear anybody needing any other gas than air when cutting acrylic. So change your worktable to blade type if possible and get a strong air support.(Which you already have, I assume.) And stay with the machine when working all the times!
As I understand, your machine isn't that small, so that the fumes would get caught inside the machine. (Working area (29" x 17") 726 x 432 mm) I assume that your machine has a decent Exhaust System too. So it seems the only thing causing the problem on such a good machine is the honeycomb worktable. If it was blade type, the cut parts would fall down and the fumes wouldn't get caught between the table and the acrylic sheet. I probably didn't say anything you didn't already know, but that's my experience with cutting acrylic on lasers. Hope it helps you somehow.
As I understand, your machine isn't that small, so that the fumes would get caught inside the machine. (Working area (29" x 17") 726 x 432 mm) I assume that your machine has a decent Exhaust System too. So it seems the only thing causing the problem on such a good machine is the honeycomb worktable. If it was blade type, the cut parts would fall down and the fumes wouldn't get caught between the table and the acrylic sheet. I probably didn't say anything you didn't already know, but that's my experience with cutting acrylic on lasers. Hope it helps you somehow.
Because of major,be at ease so.
Re: Acrylic cutting vapors popping or combusting
Thanks, I'll look into making a blade table, I would make this out of acrylic correct? I could probably make it in a 1.5"x1.5" grid, that being a wavy cut strip of acrylic with the top of the waves 1.5" apart with the strips 1.5" apart.LINUS wrote:First of all, when cutting acrylic, using a blade type worktable is much more comfortable. I'm just guessing, but with a honeycomb table the acrylic fumes might get caught between the table and the material sheet, causing mini-explosions. It's not uncommon to ignite either. To prevent that, every laser has a compressed air blower. I really didn't hear anybody needing any other gas than air when cutting acrylic. So change your worktable to blade type if possible and get a strong air support.(Which you already have, I assume.) And stay with the machine when working all the times!
As I understand, your machine isn't that small, so that the fumes would get caught inside the machine. (Working area (29" x 17") 726 x 432 mm) I assume that your machine has a decent Exhaust System too. So it seems the only thing causing the problem on such a good machine is the honeycomb worktable. If it was blade type, the cut parts would fall down and the fumes wouldn't get caught between the table and the acrylic sheet. I probably didn't say anything you didn't already know, but that's my experience with cutting acrylic on lasers. Hope it helps you somehow.
Re: Acrylic cutting vapors popping or combusting
It is possible to make a blade table out of acrylic, but I don't recommend it, because you might have to replace it quite often. And my friend who used it told me that it can cause "Burn marks" on the cut material. The purpose of the blade table is to minimize the contact between the material and the table. Generally metal blade tables with a very thin "edge" are used. I recommend you ask Trotec about it, but any Chinese blade table that fits in your machine could be used I assume.
Do you see how thin the blades edges are? It isn't called "Blade" for nothing.
Do you see how thin the blades edges are? It isn't called "Blade" for nothing.
Because of major,be at ease so.
Re: Acrylic cutting vapors popping or combusting
Thank you very much!