Introducing: Project Monocle

[mcdanlj (Michael K Johnson)]

I’ve been working on a self-designed scratch-build CO2 laser. I want a laser, and I like designing things. Rather than just doing a one-off, I’d like to make it a project that others can work from. Here were some of the key goals I had in mind:

• Parametric: The design should scale well to a substantial range of sizes; I’m trying to use 1 and 1.5 meter OpenBuilds components with minimal need for precision cutting. Scaling is easy within the range supported by cross section of chosen extrusion types.
• Space-Efficient: Uses its space envelope well.
• Cost-Efficient: Choose where to spend money for results.
• Utilitarian: My effort, at least, will focus more on results than presentation.
• Flexible: Designed to adapt to a range of fittings, such that (for example) it is easy to change out optics, motors, etc. for experimentation.
• Interesting: Do something new, don’t just create a copy of an existing design and give it a new name.

Many thanks to @NedMan for naming Project Monocle: Michael’s Open Numerically-Operated Cutting Laser Engraver.

I’ll post here about my journey; if anyone wants to join me I’d love to work together and share ideas. I mean, even working alone I intend to post about my build process here, but working together is more than twice the fun.

If you are on the fence, what min/max size and max cost would make it interesting to you to join in?

Here’s a recent view of the first iteration of my CAD model showing the general layout:

[Eclsnowman (Eric Lien)]

I love the name you guys came up with, and the logo is sweet.

[mcdanlj (Michael K Johnson)]

My current floor-standing castered model based on 1.5M X components, 1M Y components, and 1M high Z (of which almost half is open space underneath for shelves and/or cooling unit), comes in a bit under $4K inclusive of everything I’ve thought of, including ductwork and vents to exhaust fumes and a few pairs of safety glasses, exclusive of an integrated CO2 fire suppression system I’ve started pondering.

As a point of comparison, I roughed out a ~900mm x ~600mm x 250mm fixed-Z BOM as a table-top model, inclusive of 35W tube, refrigerated cooling, air assist, 4" exhaust, at under $1900. No model for that, just fudging out the rough quantities of aluminum extrusion. Note that it doesn’t actually have any need for any v-slot in that arrangement. My guess included about $300 worth of aluminum extrusion, so that limits how much money could be knocked off that estimate by finding a cheaper source of extrusion. I tried to make that estimate fairly comprehensive. Hard to buy something that large for anything like that price!

(The request was for 900x500mm but it’s basically the same cost to go to 900x600 because of available sizes of extrusion.)

Jump into the conversation with sizes that would be interesting to you, what capabilities you need, and max price it would be worth, and I can see whether this design could be modified to support what you are looking for. It will help me figure out what parameters to control as I’m starting over from scratch on the model.

[NedMan (Ned Hill)]

What are you planning to use to encase everything? For the smaller size, how much would an adjustable z-table add to that do you think?

[mcdanlj (Michael K Johnson)]

Same bed size?

I took a small short cut with the guesstimate for @clolsonus and assumed a total height of 250mm. I haven’t validated the design works but it doesn’t make that much difference anyway in the overall price. I’d definitely make it 500mm tall for a desktop model with a lift table.

Want an estimate that ignores everything you’ll might transplant from a working k40 setup? I can include that option in a spreadsheet. For a fixed-Z laser, it looks like it would be under $1K to go from a K40 to a similarly-equipped fixed-bed 900mm x 600mm reusing everything reasonable.

To add Z lift to that $1900 estimate would be 2 more 4040 500mm extrusions, 6 v-pulleys, 8 standard open builds v-slot wheel kits, 4 gantry plates, 1 8mm x 1M rod, 4 bearing blocks, another stepper, a board that can control the third stepper, a closed belt segment, two timing pulleys, and a purchased or printed worm gear box. Are you thinking the same cutting size or smaller? I’d suggest looking at the sizes lightobject sells as a starting point for least expensive way to get a bed. Looks like $150 or so delta if you print your worm gear box (I plan to try that), plus the cost of a controller if your controller can’t control the Z table. Or you can make the Z hand adjustable, saving cost for stepper and controller. You’d probably just attach a hand crank to a worm gear in that case, and a 3D printed worm box would be fine.

Your delta vs. a K40 with a new control board and stepper-controlled Z looks like about $1200, assuming you recycle as much as you can from your K40 setup.

Encasing the Monocle without breaking the bank

I’ve looked at the prices for acrylic sheet as case material for the Monocle and my heart shrank. If I’m paying that much for acrylic, I want to be shooting it with a laser to make something useful or beautiful. Heavy-duty aluminum sheet isn’t cheap either. But it needs to be encased to be safe, of course. What can I do? A CO2 laser won’t cut through aluminum even when it’s focused, at least at the power range that could possibly be installed in this machine. It won’t even cut through aluminum…

[mcdanlj (Michael K Johnson)]

I really enjoyed this post:

A Case For Project Part Numbers

If others join me on this journey, it will be something to keep in mind.

[clolsonus (Curt Olson)]

Thanks for sharing the article. I think that’s one of the hardest things … bridging the gap between common knowledge, project specific knowledge, and what a new person sniffing around might actually know. Like there might be a bunch of laser stuff that is ‘common knowledge’ that I don’t know anything about (for example.) It definitely touches on larger issues of organizing and communicating knowledge.

Example from my virtual choir project. If someone submits a song and some tracks don’t sync for some reason, they are likely to throw the whole idea in the trash and go use some other system or just give up. But I know I can pull up the song in audacity and fix the problem in < 5 minutes for most cases and rerun the song and know it’s pretty spot on. (Of course you can tweak endlessly if you have knobs to turn.) But how do I communicate that to people effectively so it syncs in, oops I mean sinks in?

As an aside, I have two choir directors that are doing their own virtual choir work in higher end tools to get a more professional/creative result, but they still send their tracks over to get ‘auto’ synced and so my system can knock out some of the more obvious noise artifacts (throat clears during a pause, etc.) I go back and forth between thinking the system is stupid and distracts people from the better path versus it does something useful for some people. The music is uplifting, when a song comes together, it’s magic, and I can kind of peek over people’s shoulders since it’s all running on a computer in my basement.