Laser Cutting surface?

[panterateama]

Hey all,

I plan on building a laser cutter CNC machine using a 3W 445nm 9mm diode/xdrive/module set from DTR.

I'm not trying to make a laser that will cut metals or heavy materials, just 1/8th woods like balsa and cardstock items. (Mind you if it is driven to 3W, I might get away with 1/4 in woods at slow speeds or multiple passes to avoid flame ups)

My main question is about the surface on which I will be cutting material. I know most industrial laser cutters use a metal honeycomb or square grid panel to sit the material on. This allows the debris and fumes/smoke to dissipate from under the material but I'm not sure where the beam goes once it passes through the material being cut?

I have heard that a thick (10mm ish) sheet of glass would be good to dissipate the focus of the beam and then maybe a metal plate below it to shield the components or frame below the build surface should work but I wanted to check here for opinions.

I thought if I could get a panel of either 1/4" or 1/2" eggcrate (square grid) panel and place it above a glass panel and that above a < 1/16th thick piece of sheet steel or aluminum should suffice. What would be the best surface finish for the metal sheet? white? black? bare metal? textured? flat? polished?

I am also thinking if I can cut grooves into the eggcrate panel between all of the walls and encase it in a fram of some sort, I could attach a vacuum of some sort (with low power and speed) to suck out the fumes and debris from below the work material.

Thoughts?

Thanks!

 

[Things]

The beam diverges rapidly once it's through the material, most machines don't need anything under the actual cutting surface at all. On my 50W cutter there is nothing but the bottom of the machine under the cutting surface, and the beam has diverged so much that it can't even melt polystyrene foam on the bottom.