So today, went to make my first laser cut project on Clifford, who is an 80w laser for one of my medical projects:
So everything was going great, except I learned a big, huge lesson about placing things on the bed.
When I asked the bed size from the shop manager he replied 48", but that turns out to be the whole bed, not the honeycomb which is 46". So why was that important, well so the edges (I asked if we should cut it down to 45, since my part was 41 x 31 and the $90 piece of 1/4" black opaque acrylic was 48x36. “Nah, it will be fine, I will adjust the focus…” he said
Well, in case you are wondering, acrylic is astonishingly flammable when it gets going. So what happened? Well the part was up on the side rails, which are maybe 3-4mm above the honeycomb, and although he put weights on each side, when the first part (about 20" square with finger tabs) fell, it was “mostly cut” so it ended up canted, sticking way up above the work piece as you can see in the picture. This snagged the head in place, which baked (especially since it was now defocused) the acrylic. Within about 15 seconds, about a square foot was on fire. Luckily there was the fire extinguisher can right there, which took a good long while to put it out (that is a large thermal mass. Some dripped down into the honeycomb sticking the piece to the bed (fun to get that unstuck). The whole sheet was pretty hot for about 20 minutes. I will note the air assist and vent aren’t awesome on this laser, even before that, but man what horrible fumes.