I notice most of the open frame LASER cutting systems use a “spoil board” under the item being through cut. This “spoil board” is usually MDF (Medium Density Fiberboard). When having been in use for awhile, I notice the board is usually well burned from being exposed to the LASER beam after target material cut-through.
This adds considerably to the fumes and smoke from the LASER operation. All enclosed type LASER machines use a non-combustible open steel support grate under the burning area to avoid generation of excess smoke. The smoke generated (only) from the material being cut, is removed by a fan drawing from the chamber beneath the grate as well as above.
I have purchased some 9 gage expanded and flattened steel mesh (3/4” hole) which will be my open grid support for material that will be cut through. Under that will be a 14 gage steel plate.
A suitable gap between the open grid and the base material will be created using 1.25 inch 1/8 inch angle iron for spacers. Grid height will be about .884 inch above the bottom plate. The purpose is to have no combustible support material under the target material.
The moving LASER beam will have no appreciable contact with any single spot on either the grid sheet or the base sheet of flat steel. Even if there was, no burning of the steel would occure. There simply is not enough power in a moving 5 watt LASER to do any damage, as the mass of the steel will absorb and disperse the heat.
What the steel base grid will do is provide a non-combustible surface needed for support during LASER cutting operation. Smoke will be controlled by a small fan blowing across the work area.
Unfortunately, I have discovered this new steel stock material is well over twice the cost of about five years ago. All I need is a 12 inch by 12 inch surface working area. This steel support base is costing nearly $70 in materials including shipping.
9Ga – .75″ Flat Expanded Steel 
14Ga, Flat Steel plate
Expect to see demonstration and use of this material support concept when I have a working LASER available! Soon…
The Steel has arrived. Happy to see it is perfectly flat. However, there are some very sharp points I will have to grind away on the expanded metal edge to make it safe to use and handle. Not unexpected. Looks like this will work exactly as I expect.
My intention is this grill will be used for cut-through activities and not necessary for standard surface engraving.
Unfortunately the expanded metal does not lay flat and can not be used as envisioned in this article. If I can find a method to hold the metal flat, I will write another blog post. Perhaps some kind of clamping to a rigid fame (?) ~ Dan
Found a good fix. I have purchased small (1.26″) 25# pull-force Neodymium disk magnets. Placed at the corners on at least three sides, the heavy mesh is pulled down flat to the solid steel base plate. I will publish the technique. ~Dan