Laser engraver bed/bottom

[npelov]

I recently bought EleksMaker laser engraver and I want to make a box for it. I'm thinking what to put on the bottom so the laser doesn't make damage. I saw that in professional lasers there is something like Honeycomb. What's the reasoning behind?

can I use the one from the second image with solid metal sheet below it?

[Fred27]

That honeycomb is design to support material that you're cutting through, to avoid marks from reflection or smoke damage to the underside. You won't need it for engraving.

[npelov]

I plan to cut some things. It cuts nicely through wood veneer, paper, cardboard. But if the bottom I use is diffusive enough it shouldn't be a problem. It's not 40W laser that can burn even if diffused. I wanted to use stainless steel sheet, but it's too expensive - I don't want rust and I plan to sand it for better diffusion which will damage the zinc coating of regular metal sheet. maybe aluminum sheet is an option.

[dmills]

Just be careful, any laser that cuts anything is likely to be class 4 and reflected light is dangerous to your vision.

Personally I think honeycomb is a pain in the arse (Difficult to clean) far better to use a set of parallel thin bars (Edges of thin steel sheet) as you can reasonably run a rag along that style of bed to clean them.

Regards, Dan.

[ajb]

Honeycomb also allows for downdraft ventilation, which helps keep a clean cut when cutting through, and when the downdraft is strong enough provides good workholding for thin materials.  This is a big help when cutting thin films that may otherwise be blown about by air assist or crossflow ventilation.

I'm not sure that you could build a bed of thin parallel slats that was sturdy enough without starting to worry about reflection/obstruction spoiling your edges on sensitive materials, and anyway I don't think we've ever cleaned the honeycomb in our Epilog, although it did get replaced due to physical damage once, but then we're not cutting a lot of really sooty materials.

[npelov]

Yes, it is pretty dangerous and the glasses are not the best protection. That's why I'm building a box around it.

@ajb you say downdraft makes cleaner cut. Since I'm designing the box should only allow air to pass through the cutting area? Honestly I don't think I'll cut materials that often. Most of the time the laser will engrave. I don't have air assist though. The only air (currently) on the engraved area is from a 30x30mm fan that's meant to coll the laser. Maybe I can add one more that's blowing directly on the laser dot. It does start fire when I cut through thick cardboard and sometimes on veneer too. But does air assist help that much with engraving at lower power?

[ajb]

Air assist can be hit or miss with engraving.  It does often reduce fire risk, but depending on how it's configured, can blow smoke/vapors back down onto the workpiece, so you can wind up with extra gunk to clean off.  This is the situation with our epilog, where the air assist comes in from the front, so as the engraving progresses the air assist blows gunk onto the area that has already been engraved.  A proper air assist nozzle that makes the air stream more or less colinear with the beam is probably better in that respect.  I'm not sure that a small fan aimed at the workpiece will be as effective as a proper air assist jet, but you could try it.

If you're not doing a lot of cutting, then downdraft is less advantageous, unless you're mostly engraving small pieces that don't cover the entire table.  For engraving large pieces, crossflow is the better way to go.