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Aluminum Frame Enclosure

So you want to build a laser enclosure. Lots of options are available, as an enclosure can be made from all kinds of materials, or, adapted products. For example, you could use a cardboard box. Or, use a grow tent like I did for a few years. After using that for a while, I decided to build a more proper enclosure, one that would suit my various needs of today, and could be adjusted/repurposed later if I wanted. I decided to base it on an aluminum extrusion frame, 2020 profile to be exact. Skip down to Build to bypass the reasoning process and general discussion of why I chose this route.

Frame Material Considerations

Wood framed enclosures are a popular choice, particularly if you’re handy, already have the various tools needed, (saws, drill, bits, common hand tools), and a space to make a sawdust mess in. It’s a relatively cheap option, particularly if you already have some old lumber hanging around. Sure, some of the big box stores will cut wood for you for free, but if you’ve ever tried that, you’ll know what a huge time waste that can be. For myself, the big downside of using wood is that wood is, after all, combustible, and we’re talking about using it with something that could in fact set that wood on fire just in normal operation. If the unit inside catches fire (yes, this does happen), then that is going to be fuel. Some companies which offer laser engravers do have flame detection sensors, but that simply causes the laser to turn off, not put out the fire. There are some other options to help with this that I’ll touch on later.

Using rigid foam board is another route some people go, with and without a frame. These are easy to build, needing only a utility knife and some tape. There is a concern however about what could happen if there was a fire inside an enclosure like this. Think toxic fumes, rapid intense heat, and a few other not so pleasant outcomes. In many ways, a cardboard box would be better choice.

Bigger lasers, such as the K40 semi-hobbyist class, use metal enclosures. If you’re a metal worker, that’s a great option, as you have all the tools and knowhow for making one. If you happen to have a metal box already the right size, it’s a good start point, assuming you have the tools and knowledge of how to adapt it to your purpose.

Then there are aluminum extrusions, which are the basis for most hobbyist 3D printers, laser engravers, and more. It’s a widely adopted standard used in businesses around the world because it’s strong and easy to work with. As such, there are accessories galore ready to go, you can pick extrusions in various pre-cut lengths, and pricing isn’t through the roof. More than wood, yes, and you can’t exactly run down to the local Home Depot or Lowes to get some. Oh yes, and they’re based on the metric system, which could have some people’s underpants in a bunch. I should mention, one can cut these to size at home, order custom lengths, and/or join lengths together. Outside of cutting, the only tools needed to work with aluminum extrusions are an Allen wrench set.

Wall Material Considerations

Regardless of frame type, you still have to choose wall materials. The 2020 profile has channels that are just a hair under ¼” wide and deep. Those channels are perfect for seating wall material into. The big box stores offer lots of options for wood, and most all ¼” wood is actually a little less than that size (just as a 2×4 isn’t actually 2″ by 4″). There are <¼” options too, but those require something extra to hold the wall material in the channels tightly. Without, the walls will rattle. But wood was not what I wanted, the whole fire thing. Nor foam insulation board. Plexiglass was possible, but cost prohibitive.

What I settled on was cement board, the same stuff used under floors and countertops to provide a rigid surface to adhere tile and countertops to. Aside from being a moisture barrier, it’s also fireproof, being 80-90% concrete. It comes in smaller sheets (3’x5’x1/4″) that are pre-scored, aren’t overly heavy, and can be further scored by a utility knife (painfully and slowly). Cost for a sheet was less than wood, bonus! The downsides on these is that they are actually ¼” thick instead of being undersized, and, you need a mask (which you already have, thanks Covid) if you’re going to make a bunch of dust with them (sanding, cutting with power tools, etc).

Options and Sizing

A typical laser engraver will fit neatly in a 24”x24” wide space, with 12” height. But you may want to think about what options you want to add on. Lighting will take up some room, as will a spoil board. More height is needed if you plan to use a rotary and/or camera. The size of your exhaust and intake ports need to be taken into account, and, the ever important door(s). And if you’re really wanting to go all out with safety, a fire suppression system like a Blazecut needs a little bit of space too.

For corners, there are a couple of different ways to go. There are cubes, which will require you to tap the center holes in the extrusions, exterior L brackets of various types and sizes (bolt on), 3-way corner pieces (bolt on), exterior L joints (bolt on), internal L joints (bolt in), exterior gussets (bolt on), and more. For all the exterior bolt on types, you have to keep in mind that they can interfere with whatever door setup you’re thinking of. The interior types on the other hand can get in the way of wall material. The one with the least fuss here is the 3-way, which sits in the outer channels at the corners, and don’t get in the way much or at all.

Build

For me, I ended up going with essentially a 29” cube, using (12) 700mm extrusions and (3) 3-way corner pieces. It may seem oversized, but that’s because it is. When I switch laser units out for testing, maintenance, and the like, I want to leave the camera system, cables, power supply, and exhaust system in place. This will also let me put one of my 3D printers inside if/when I decide to try printing in ABS or other materials which need exhaust and temperature stability.

The first thing to do was mock up the bottom of the enclosure so that measurements could be made. The corner pieces slide in the channels of the 2020, and get held there by the built in grub screws. Now that the bottom frame was assembled, I took measurements for all sides to determine how big the piece of cement board needed to be. To account for the channels, an extra 7/16” needed to be added on so that the cement board would sit in the channels without interfering or flapping around much.

Measurements made, it was time to cut the cement board. The scoring on the stuff I got was done in 1” squares, so that it was fairly easy to get into the general size I needed. Had I been working in whole inches, that would have been perfect. But no, fractions were needed. Using a ruler, I added the fractional value to the total length on both sides of the cement board. Then I ran a line between the two marks, using the edge of another board. The “right” way to do this would be a carpenter’s square, yard stick, 3’ or longer level, or a chalk line, but using a reasonably straight board edge worked well enough. That took care of the length. Using the same technique, I did the width. Note, it’s best if you use the board’s corners as your start location, so that you get at least two straight edges no matter what. LOL.

Once marked off, it was time to cut. The maker of these boards, Hardibacker, says that they can be scored (cut into a little ways) with a utility knife, then snapped along the score line. And yes, it does work. But, it’s murder on your blades, not to mention hands. Cement is abrasive, and within one cut, the tip of my blade was rounding off. It didn’t help that I had to go over it some 40 times either. Once well scored, the board did indeed snap along the score lines as advertised, so there’s that. After two sections were cut, I was out of blades, and went to find a better method.

Turns out they make a tool for this, which uses carbide tips to dig into the board without taking much damage. It’s like $10, and available at hardware stores. Then there is the power tool method. As mentioned, dust is a problem with these, you don’t want to breath it in or get it in your eyes if possible. The best power tool for the job is the jigsaw, mated with a blade specially made for cutting these boards. There is some dust, but not as much as using an angle grinder or circular saw. You can wet the surface to help keep the dust down too. As it happens, I have a jig saw, the blade is another $10, and it was available at the hardware store. I stepped out and spent the twenty bucks on both items.

The scoring knife worked great compared to the utility knife. It dug into the cement board without a ton of pressure and while I still needed to do a good number of strokes to get the board scored well enough to snap, it was much easier and faster. Not as fast as the jigsaw though. With the special blade on it, my el cheapo jigsaw went through the cement board like butter. Dust in the air wasn’t too bad, but way more than with either of the knives. Next time, I’ll douse the board with water or bring the vacuum along.

Anyhow, board cut, it was time to fit it into the bottom frame. This is when I discovered that the boards were actually ¼’ thick, which is too thick to fit into the channels. The fix – bevel the edge. To do this, you can break out the utility knife and slice along the edge at an angle to make the edge thinner. Or, you can sand it. Both work, I tried them, but sanding throws up more dust. Trial and error with a spare piece of 2020 let me know when I’d trimmed well enough, the board settled into the channels nicely, and I tightened all the corners.

From here, I went on to do the top assembly, so that when the sides were all done and in place, I could just slip the top assembly on. Once that was done, I took measurements for the side walls and back wall. They aren’t the same as the top and bottom walls, because of how the 3-way corner pieces work. When I said “essentially a cube”, this is why. Anyhow, I also had to contend with one side wall being a two piece affair with an extra 2020 length running front to back. This was intentional, as I am mounting a camera over the center of the closure, about ¾ of the way up.

For the exhaust port, I needed a hole in the side wall capable of handling a 6“ vent hose. If you want to cut a circle, the best method is to trace your circle out, then divide it up like a pie, and then use the scoring knife along all the lines. When well scored, smack the center with a hammer, your palm, or whatever, to snap the pieces free. If you’re into pre-planning, and have the tools, you could use a drill with a sizable bit and the jigsaw with the good blade to cut the circle out. If you opt for a vent cover, like the ones used for laundry and such, you can cheat a little by making a square opening, which is then hidden by the cover. Confession, I made a 5″ square and stuffed the 6″ hose in it. Yes it’s ugly. Maybe I’ll fix that.

When it comes to cable ports, you’re in the same boat, though drilling a hole big enough to fit the fattest end of your cables through is easiest.

This is probably a good place to tell you that you don’t need this enclosure to be airtight. Any opening you have in the enclosure will serve as an air intake port, which is something you need for your exhaust to work. So don’t sweat it.

Now for the doors. Confession, I haven’t made them yet. Instead, I slip some laser safety plastic sheet into the front bottom channel and side channel. The exhaust fan, the port of which sits a bit higher than the laser work area, takes care of the rest. The vacuum it creates sucks in all the smoke and scent. The plan however is to build a set of double doors from more extrusion and use the safety plastic as window inserts. Hinge and handle kits are readily available for less than $20, and these bolt right on.

FAQ

-What is your bill of materials(BOM) so far?
(none of the links are affiliate links)
  1. (13) 700mm 2020 T slot extrusions (V slot will work too) https://smile.amazon.com/gp/product/B083BJ42NZ
  2. (8) 3-way corner pieces
  3. (3) 3’x5′ cement boards https://www.homedepot.com/p/James-Hardie-HardieBacker-3-ft-x-5-ft-x-1-4-in-Cement-Backerboard-220022/100183556
  4. (1) 24″x24″x3/4″ plywood board (spoil board) https://www.homedepot.com/p/Columbia-Forest-Products-3-4-in-x-2-ft-x-2-ft-PureBond-Poplar-Plywood-Project-Panel-Free-Custom-Cut-Available-2922/204853871
  5. (1) 24″x24″ 22 gauge sheet steel (sits on spool board) https://www.homedepot.com/p/Everbilt-24-in-x-24-in-22-Gauge-Plain-Sheet-Metal-800627/204325595
  6. (1) 500mm 2020 T slot extrusion (to mount camera) https://smile.amazon.com/gp/product/B0937F6HTV
  7. (1) 2020 compatible M6 camera mount (designed and 3D printed myself)
  8. (2) 2020 external L brackets (camera mount) https://smile.amazon.com/Iverntech-78x78mm-Aluminum-Extrusion-Brackets/dp/B094CTX1VX
  9. (6) M5 8mm hex screws and T nuts (camera mount)
  10. 25′ of 6″ exhaust ducting https://smile.amazon.com/gp/product/B0791V19H7
  11. 16′ of 5“ exhaust ducting https://smile.amazon.com/gp/product/B07H27G2L9
  12. 6″ to 5″ ducting adapter https://smile.amazon.com/gp/product/B08KWH5BPC
  13. 6″ inline exhaust fan https://smile.amazon.com/gp/product/B0936JXYLV
  14. Exhaust dust window insert (put it in when you’re using the laser, pop it out and close the window when not) https://smile.amazon.com/gp/product/B095JGST58
  15. LED light strip (interior lighting)
  16. (2) 12”x24” Laser safety plastic sheets https://jtechphotonics.com/?product=445nm-laser-shielding-24-x-12
  17. (1) 4k USB camera with auto focus, no distortion https://smile.amazon.com/gp/product/B09D3JZ9C9
-What other things might I want?
  1. An air quality monitor wouldn’t be a horrible idea. It will let you know if your exhaust isn’t working, you forgot to turn it on, or something else has gone wrong
  2. Smart outlets or smart powerstrip. It’s rather fun to tell Google Assistant/Alexa/Siri to switch things on and off for you.
  3. Exterior braces. The 3-way corners do ok, but I’m planning on reinforcing them after seeing that I could wiggle the cube a bit
  4. An array of M3-M6 hex screws and T nuts. They’re invaluable for adding stuff to the frame and will be needed for the above braces most likely.
-Why would I want a camera in there when I can just look through the window?
  1. Ah, but when/if you have Lightburn to use with your engraver, you’ll have a whole new world of fun with a camera. Sure, it can watch the laser do its thing, but, that’s pretty pedestrian. Instead, it can be used for visualizing material and artwork placement. You toss your material in there, the camera shows you where it is and how it’s positioned, you align your art to the camera image, and off you go.
-Is there anything besides 2020 extrusion? It looks kinda thin…
  1. Certainly! 2020 is, literally, 20mmx20mm square, hence its name. You can get variations of 2020, such as a 2040, which is 20mmx40mm in size, exactly equal to two 2020 sitting side by side. There is also stuff like 4040, 8080, etc.

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