16 Comments

Thanks for the 110-page tome. I really got a lot out of it and eventually decided to give it a try. After waiting for ages, a really cheap MDX-15 came up on eBay and it worked well enough. So I learnt some FreeCad and knocked out this for a friend's birthday: http://www.ashurst.eu.org/download/tmp/gal-charlie-chocs/index.html

Other than cutting one side of a chess piece STL I downloaded from somewhere to test the machine, that's the first thing I ever did with CAD/CAM and your guide was instrumental in making it accessible.

Thanks!

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Hah, that's pretty sweet! Great detail.

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Your treatise is a real treat. Thank you. I will be unpacking it in the weeks to come.

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> Just as importantly, CAM shouldn’t be your only tool: for simple tasks, the process is needlessly time-consuming and error-prone.

What's CAM? Did you mean CAD?

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Sorry, too much jargon. CAD is "computer-aided design", and typically refers to 2D or 3D modeling software that lets you sketch the thing you want to make. CAM is "computer-aided manufacturing", and this commonly refers to the task of taking your CAD model, turning it into tool movements, and talking to the machine.

So, when you're designing a figurine in Blender, that would be "CAD". When you're loading the finished model into a slicer and sending it to a 3D printer, that's "CAM".

In this particular, context, it's interchangeable, I was just trying to say "don't solve every problem with a computer".

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hear hear! I wish I could afford a (decent, enclosed) laser cutter. There's a lot that can be done with just stock flat material, whereas trying to FDM print a flat sheet with holes in specific places takes hours and hours. Drilling by hand is horrendously error prone, esp when you are trying to cut holes for a M2 screw (Pi Pico mounting).

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What should a beginner look for in a desktop CNC? I now know what to look for in a 3D FDM printers and think I know what to look for in a laser cutter, but desktop CNCs is beyond me at the moment.

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Rigidity. Unlike 3D printer that needs just not to sway from accelerating the extruder, mills need to push the tool against material pretty hard. I worked with one that used metal line on pulleys for driving mechanism, and you'd use it at snail's pace with 2mm tool, taking 0.2mm per layer to achieve any sort of precision and not break the tool. Even small works took multiple days. And I worked with industrial one. Granite gantry that looked like a tombstone, inch thick drive screws, mighty steppers... and it was incredible, fast and precise.

So, what to look for? The thing should look *chonky. Thick, firm frame, drive screws instead of belts, soli guide rails, strong head. Of course all that won't be cheap, but any sacrifices to the structure are serious sacrifices to precision and speed, and what you can work with. If you swap out the extruder for a dremel on Ender 3, you can work with styrofoam, take it up from there.

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The decision is less about the machine and more about the process. Unless you're building cars or guns, or running an injection-molding shop, you probably don't need to routinely work in metal, and that greatly simplifies your life - you can buy a more lightweight unit, stock materials are easier to handle, and you don't have issues with noise, cooling, etc.

The other important question is the size of the parts you want to make. As noted, a CNC mill (or a 3D printer) should not be the one and only tool in their workshop. Large parts usually have simple shapes and can be cut with a saw or something like that.

With this out of the way - for a desktop model and easily-machined materials, I'd probably look at Nomad 3. You can buy much cheaper devices from China, but if you don't want to spend time QAing the machine with a dial gauge, the Nomad is a safe pick.

For woodworkers who don't need micron-level precision but need to cut large sheets of material, check out Shaper Origin - it's a cool hybrid device that is operated by hand, but displays your CAD template overlaid on your workspace and then corrects your hand movements.

If you do need to chew through metals quickly, then desktop / portable units are out because you need a very rigid frame and beefy motors. Then, you're looking at stuff like a Tormach or a Syil mill, and are probably spending more.

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These are both $2800 machines, which I think goes a long way in explaining why they aren’t popular with hobbyists. Too bad TechShop isn’t around anymore.

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I think it's the other way round. The price of "turnkey" hobby 3D printers has gone down significantly because you can sell more. It used to be that cheap printers would require painstaking assembly and fine-tuning. Now, for that price, you get a pretty polished experience out of the box.

But you can have CNC mills for a couple hundred bucks - it's just that I don't want to recommend an ephemeral brand that ships from China and has non-existing customer support. It can work out fine, but it can be a nightmare without a community to help you along the way.

I mean, you even have sub-$200 stuff like this: https://www.amazon.com/Genmitsu-3018-PRO-Control-Engraving-300x180x45mm/dp/B07P6K9BL3/

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I’m wondering if there’s a good middle ground here, comparable to spending <$1000 on a Prusa?

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There are some credibly-looking designs for that price, but again, I'm wary of random brands from China if you can't be sure about QC and can't get community support. There are some US-made choices around $1k in the "let's strap a router to a gantry" category, though - e.g.:

https://millrightcnc.com/product/millright-cnc-carve-king-kit-2/

I'm sure this works well if you're not doing anything ultra-precise.

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Thank you. That should enable me to get closer to a decision :-)

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The company mentioned is https://nopak.com/about/

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Watched servo and stepper motors added to Southbend Lathes & Bridgeport Knee Mills. Built a RepRep that made crude parts & put controls on a 14x14x5” tabletop router, Donated both to a museum’s hacker basement in SLC.

Know a 126+ y/o Milwaukee factory that had 130 employees manually milling valves & cylinders, had a night shift as well. They are now about 12 employees and everything is CNC.

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