Back when I was lasing with my original Chinese laser, I spent months looking for anything affordable that would provide the one main reason for using a cutting table instead of a flat solid engraving surface: maximize airflow away from the material being cut.
Good airflow allows for a cleaner and more efficient cut and reduces smoke deposits on the underside of the material.I spent hours in the hardware stores, big box stores, and anywhere else I could think of in search for an almost ready made solution. Sure, there were some products on the web, but most were add on features when buying a new laser. And the few I could find that were available to adapt to my laser were expensive. Then one day, sitting in my office with my head tipped back, staring at the ceiling, inspiration came. Actually I found myself looking at the fluorescent light fixture above my head and there it was - a light grid. The one in my office is plastic and the grids were sloped to provide more light disbursement, but it reminded me of some aluminum grids I had seen 20 years ago. Surely I only needed to find that style and I would be all set.
That night I made a trip to the big box store and looked at every metal light grid they had - which was exactly zero. They did, however, have a plastic one that had straight grids and it was only a couple of bucks for a 2' x 4' piece. I took it home, cut a piece the appropriate size, and tried it out. It worked pretty well. It had two items on the downside, however; it melted a bit from the heat of the laser, causing it to begin to sag in the middle, and the smoke from the plastic as the laser passed over the plastic ribs of the grid produced additional smoke that was deposited on the back of the work material. Still, it was cheap, easily replaceable, and most materials could be cleaned off. So that is what I used for several months.
When I starting thinking about building a new laser, I restarted my search for the perfect laser cutting table. I found 1 inch honeycomb aluminum core at McMaster-Carr. It wasn't exactly cheap (about $75 for the 24"x24" piece), but it should do the job. It had a minimal footprint leaving lots of room for airflow. Besides, I was building a nice laser, I could afford to spend a few extra dollars to get it right this time.
They told me it was an aluminum grid with straight ribs and 1/2" spacing. They were buying it in larger sheets and cutting it to size as people ordered it. The price for my laser (about 12" x 24") would be $75 plus shipping. I did not want to order right then. After all, if they are buying it in larger sheets, then I ought to be able to do so as well, right?
I searched for about a month. The problem was that I did not know what to call it, and searching for "aluminum grid" just wasn't finding it for me. Recently I was reading a post on BuildLog.net that talked about ordering a laser cutting table from a particular source on the web. It happens it was the same place I had inquired earlier. The interesting part was what the poster called it - "Eggcrate Grid". Hah! A name for it. That should make searching much easier.
I shortly found that eggcrate grid is commonly used as vent covers in the HVAC industry; particularly in commercial installations. There are plenty of places on the web to order those covers, in a wide range of sizes, but most did not included prices; the sites were mostly for contractors and you need to inquire first. I checked locally with contractors but they did not keep it, and they would have to research it and get back to me. Stuck again!
Fast forward about about a week. I ran into an acquaintance that is an HVAC maintenance guy at a very large company. So I asked him about eggcrate grid vent covers. He was not familiar with the term, but after hearing my description, his response was "How much do you want - we through that away all the time." I asked for one piece at least 12"x24".
A couple of hours later he tracked me down and handed me a piece 24"x48". Wow! Where did you get that? He said he did not have any in the HVAC area, but his friends in electrical did - it was aluminum fluorescent light grid with straight ribs and 1/2" squares. Gee, why didn't I think of that!!!
I rushed home, cut a piece to fit my table frame, built an aluminum frame around it and gave it a try. It works great. The only down side is that it is painted white instead of bare aluminum. I may take it out and sand blast it to clean it off.
I made it bigger than the 12" cutting area I have. I made it fill the entire laser table top frame; I didn't want to bother butting in an extra frame member for attaching the rear edge of the grid. But I still have enough left to make one more, if I want.
My friend told me that the reason they throw it away is because everyone is going to plastic, so they only had a couple of pieces of new material. (I am hoping to get the few pieces they have left.) But, I can't help but believe that it still exists someplace out there.
Even though I can finally end my search for the perfect cutting table, I'll continue my search for a reliable source. When I find it, I'll pass it on to you!
UPDATE 09/26/2011 11:10: A friend over at BuildLog.net found this ebay listing for the same material.