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Shameless plug if anyone is interested - I'm working on a $600-ish open-source, reasonably capable, but small and somewhat "tidy" hobby CNC machine with BOM cos

by sottol 2y ago

Shameless plug if anyone is interested - I'm working on a $600-ish open-source, reasonably capable, but small and somewhat "tidy" hobby CNC machine with BOM cost around $600 that requires some DIYing. It's meant to be an alternative to the Desktop CNCs like Nomad, Carvera, Bantam, ... moreso than a PCNC or other proper entry-level CNC. The ultimate goal is to make it hobbyist-friendly, capable of easily cutting alumin(i)um and not taking up a lot space, not being messy or loud enough to require a dedicated workshop. Unfortunately, cutting metal is inherently loud so you probably would not be able to run it in an apartment as I'd hoped. I've made a couple decisions around being friendly for people coming from the 3DP space around probing, using roborock CPAP as chipvac, running it mostly dry, fully enclosed. I'm also starting to work on computer-vision-based probing and the idea is to later enable a host of more user-friendly and safety-focused features and maybe integration with Kiri:Moto's CNC mode for "guided" CAM and so on - basically a beginner-friendly CNC that guides newbies using an integrated web-interface. More info on Github: https://github.com/thingsapart/mini_nc https://github.com/thingsapart/mini_nc GH is a little outdated but I've been using the little machine to cut alu for a while (mostly parts for itself) and it's working quite well. There's more videos and such on the Discord linked in the GH readme - feel free to ask questions on the Discord, I try to respond as quickly as I can. The full model with all its components is completely open in Onshape (I know it's not ideal but how I learned CAD - link also on GH).

hnisoss 2y ago
that looks like a nice project, reminds me of the ghost gunner 3 machine. I like the safety note too. might hop into discord sometime next week. thanks for sharing!
deleted 2y ago
[deleted]
mdorazio 2y ago
What's the advantage of this over a 3018 or 3030 machine? With some basic upgrades (you mentioned needing to diy anyway) you can easily cut aluminum on those for $500 or less.
- bluGill 2y ago
  Not made in china though since many parts come from china anyway...
  - deleted 2y ago
    [deleted]
- sottol 2y ago
  I tried [1] - replaced the sides with 2040s, blind-jointed every extrusion, replaced X with MGN12H + 4 carriages, replaced the whole Z with 4080U and even bolted it into an MDF box to stiffen it up. The 3018 could cut alu, but not well. Maybe it was the 4080U but it just didn't work for me, it could cut alu but had lot of chatter. For $600-800 it is fully enclosed, includes a decent spindle, wifi-enabled +offline RRF-based controller with folding/rotating LCD screen, 2 power supplies (24V + 48V for the spindle), a chip vacuum and probably some more I forget. This machine was designed [3] specifically to cut alu rather well for < $1000, can run adaptive clearing toolpaths at 0.5mm optimal load and 3mm doc at 1800 mm/min with a 6mm end mill and produce decent chips. It can probably do more, my standard settings are 1200mm/min, 0.5 woc, 3mm doc. Mind you, this is all still hobby-level though you could still push the feeds and speeds a bunch I reckon. [1] https://youtube.com/shorts/C0ngUJrWrB4 https://youtube.com/shorts/C0ngUJrWrB4 [2] https://youtube.com/shorts/XUsj06iMbb0 https://youtube.com/shorts/XUsj06iMbb0
- deleted 2y ago
  [deleted]
throwaway81523 2y ago
This would be a lot more interesting if it could cut steel and titanium. I guess that is more difficult. Added: a dumb question, if the main cutting device is a router with a spinning bit, how do you cut angles? One thing I'd like to make is a 4mm hexagonal hole in a piece of steel, to turn little hex drive screwdriver bits and the like. Is it even possible to make that with a mill, or do you need a different machine?
- aaronblohowiak 2y ago
  Steel is sooooooooooooo much harder than al, it’s not even in the same ballpark. Aluminum is about as hard to cut as wood. For non round holes, you are looking at approximations or broaching. Look up manual hex broaching
- Animats 2y ago
  That's usually done with something called a rotary broach.[1] This is a clever trick. You first make a round hole. The rotary broach is a hex-shaped cutting tool. Both workpiece and tool are clamped in a lathe. But the center of the tool is slightly offset from the rotational center of the workpiece. Both spin, but the eccentricity makes it cut a hexagonal hole. Here's the process.[1] A milling machine can cut a hexagonal hole, but the inside radius at each corner cannot be smaller than the radius of the cutter. A 4mm hex hole would require a tiny cutter to do a good job. Here's that process for a larger hole.[2] If the hole goes all the way through, just get a hexagonal punch. Might need to drill a round hole first. Or just buy a 4mm socket with a T-handle. Cost US$4.99.[3] [1] https://www.youtube.com/watch?v=_AYEFjbGaL4 https://www.youtube.com/watch?v=_AYEFjbGaL4 [2] https://www.youtube.com/watch?v=zOqSIRuBgCY https://www.youtube.com/watch?v=zOqSIRuBgCY [3] https://www.amainhobbies.com/rc4wd-metric-hex-twrench-tool-4.0mm-rc4zf0031/p667266 https://www.amainhobbies.com/rc4wd-metric-hex-twrench-tool-4...
  - throwaway81523 2y ago
    Thanks, yeah, a separate 4mm socket with a handle is certainly a possibility, but I liked the idea of a 4mm hex hole in something like this, to accompany the holes that are already there: https://knifeworks.com/crkt-9100kc-eatn-tool-black-oxide-finish/ https://knifeworks.com/crkt-9100kc-eatn-tool-black-oxide-fin... I'll look at the rotary broach video. Yes the hole would go all the way through, so a punch sounds ok. Anyway it's not about making this one hole. It's more an example of the kind of stuff I'd like to do with metalworking gear if I had access to it and knew how to use it. It does sound like hard materials are an obstacle as well. Aluminum is a start though.
sottol 2y ago
I uploaded a quick video of it cutting some alu recently if anyone's interested: https://youtube.com/shorts/XUsj06iMbb0 https://youtube.com/shorts/XUsj06iMbb0
- sgnelson 2y ago
  At first I was skeptical, but that's an impressive demo for such a small machine. The documentation on your github is a tad lacking however. :) But good luck on your machine, I like your CPAP fan idea.
  - sottol 2y ago
    Documentation is definitely lacking - I just got the design to a point where I'm pretty happy with it. So far only 1 machine exists and the build has a few bits that are... less than ideal. The plan was to build a second machine and optimize some of the assembly, take notes and document the build.
Animats 2y ago
Fully enclosed with a chip vac is good. Chips all over the place is no fun. Especially with coolant. Don't expect people to precision-cut wood for the frame. The Liteplacer people tried that for their pick and place machine, and most people never got a working machine. If it needs plates with holes in them, make them in bulk and sell them. Waterjets are good for that. The holes will be where they are supposed to be. (The Liteplacer was a really good idea - a pick and place machine for assembling prototype PC boards. Camera controlled, with the input parts in partitioned trays rather than reels, it was slow but did the job precisely. The PixiePlacer seems to be the next generation of this. But, as with the Liteplacer, you can't just order the metal parts. You have to make them or have them made. There are commercial machines, of course, but they're for production, feed parts from reels, and are more expensive.)
- aaronblohowiak 2y ago
  What about the lumen from opulo?
  - Animats 2y ago
    That's neat, but it's meant to get its parts from feeders. It's a small-volume production machine.
- sottol 2y ago
  Good point - there is a provision for laser-cut steel or alu plates that sit inside pockets inside the enclosure panels as I figured many would be turned off by a full plywood design. The metal parts are symmetric so you can cut 2x of each - that is way cheaper on send-cut-send (afair only 25% extra for 2nd part).
  - Animats 2y ago
    > plywood design. Coolant and plywood do not play well together.
    - sottol 2y ago

by sottol 2y ago

hnisoss 2y ago

that looks like a nice project, reminds me of the ghost gunner 3 machine. I like the safety note too. might hop into discord sometime next week. thanks for sharing!

deleted 2y ago

[deleted]

mdorazio 2y ago

What's the advantage of this over a 3018 or 3030 machine? With some basic upgrades (you mentioned needing to diy anyway) you can easily cut aluminum on those for $500 or less.

bluGill 2y ago
Not made in china though since many parts come from china anyway...
- deleted 2y ago
  [deleted]
sottol 2y ago
I tried [1] - replaced the sides with 2040s, blind-jointed every extrusion, replaced X with MGN12H + 4 carriages, replaced the whole Z with 4080U and even bolted it into an MDF box to stiffen it up. The 3018 could cut alu, but not well. Maybe it was the 4080U but it just didn't work for me, it could cut alu but had lot of chatter. For $600-800 it is fully enclosed, includes a decent spindle, wifi-enabled +offline RRF-based controller with folding/rotating LCD screen, 2 power supplies (24V + 48V for the spindle), a chip vacuum and probably some more I forget. This machine was designed [3] specifically to cut alu rather well for < $1000, can run adaptive clearing toolpaths at 0.5mm optimal load and 3mm doc at 1800 mm/min with a 6mm end mill and produce decent chips. It can probably do more, my standard settings are 1200mm/min, 0.5 woc, 3mm doc. Mind you, this is all still hobby-level though you could still push the feeds and speeds a bunch I reckon. [1] https://youtube.com/shorts/C0ngUJrWrB4 https://youtube.com/shorts/C0ngUJrWrB4 [2] https://youtube.com/shorts/XUsj06iMbb0 https://youtube.com/shorts/XUsj06iMbb0
deleted 2y ago
[deleted]

throwaway81523 2y ago

This would be a lot more interesting if it could cut steel and titanium. I guess that is more difficult. Added: a dumb question, if the main cutting device is a router with a spinning bit, how do you cut angles? One thing I'd like to make is a 4mm hexagonal hole in a piece of steel, to turn little hex drive screwdriver bits and the like. Is it even possible to make that with a mill, or do you need a different machine?

aaronblohowiak 2y ago
Steel is sooooooooooooo much harder than al, it’s not even in the same ballpark. Aluminum is about as hard to cut as wood. For non round holes, you are looking at approximations or broaching. Look up manual hex broaching
Animats 2y ago
That's usually done with something called a rotary broach.[1] This is a clever trick. You first make a round hole. The rotary broach is a hex-shaped cutting tool. Both workpiece and tool are clamped in a lathe. But the center of the tool is slightly offset from the rotational center of the workpiece. Both spin, but the eccentricity makes it cut a hexagonal hole. Here's the process.[1] A milling machine can cut a hexagonal hole, but the inside radius at each corner cannot be smaller than the radius of the cutter. A 4mm hex hole would require a tiny cutter to do a good job. Here's that process for a larger hole.[2] If the hole goes all the way through, just get a hexagonal punch. Might need to drill a round hole first. Or just buy a 4mm socket with a T-handle. Cost US$4.99.[3] [1] https://www.youtube.com/watch?v=_AYEFjbGaL4 https://www.youtube.com/watch?v=_AYEFjbGaL4 [2] https://www.youtube.com/watch?v=zOqSIRuBgCY https://www.youtube.com/watch?v=zOqSIRuBgCY [3] https://www.amainhobbies.com/rc4wd-metric-hex-twrench-tool-4.0mm-rc4zf0031/p667266 https://www.amainhobbies.com/rc4wd-metric-hex-twrench-tool-4...
- throwaway81523 2y ago
  Thanks, yeah, a separate 4mm socket with a handle is certainly a possibility, but I liked the idea of a 4mm hex hole in something like this, to accompany the holes that are already there: https://knifeworks.com/crkt-9100kc-eatn-tool-black-oxide-finish/ https://knifeworks.com/crkt-9100kc-eatn-tool-black-oxide-fin... I'll look at the rotary broach video. Yes the hole would go all the way through, so a punch sounds ok. Anyway it's not about making this one hole. It's more an example of the kind of stuff I'd like to do with metalworking gear if I had access to it and knew how to use it. It does sound like hard materials are an obstacle as well. Aluminum is a start though.

sottol 2y ago

I uploaded a quick video of it cutting some alu recently if anyone's interested: https://youtube.com/shorts/XUsj06iMbb0 https://youtube.com/shorts/XUsj06iMbb0

sgnelson 2y ago
At first I was skeptical, but that's an impressive demo for such a small machine. The documentation on your github is a tad lacking however. :) But good luck on your machine, I like your CPAP fan idea.
- sottol 2y ago
  Documentation is definitely lacking - I just got the design to a point where I'm pretty happy with it. So far only 1 machine exists and the build has a few bits that are... less than ideal. The plan was to build a second machine and optimize some of the assembly, take notes and document the build.

Animats 2y ago

Fully enclosed with a chip vac is good. Chips all over the place is no fun. Especially with coolant. Don't expect people to precision-cut wood for the frame. The Liteplacer people tried that for their pick and place machine, and most people never got a working machine. If it needs plates with holes in them, make them in bulk and sell them. Waterjets are good for that. The holes will be where they are supposed to be. (The Liteplacer was a really good idea - a pick and place machine for assembling prototype PC boards. Camera controlled, with the input parts in partitioned trays rather than reels, it was slow but did the job precisely. The PixiePlacer seems to be the next generation of this. But, as with the Liteplacer, you can't just order the metal parts. You have to make them or have them made. There are commercial machines, of course, but they're for production, feed parts from reels, and are more expensive.)

aaronblohowiak 2y ago
What about the lumen from opulo?
- Animats 2y ago
  That's neat, but it's meant to get its parts from feeders. It's a small-volume production machine.
sottol 2y ago
Good point - there is a provision for laser-cut steel or alu plates that sit inside pockets inside the enclosure panels as I figured many would be turned off by a full plywood design. The metal parts are symmetric so you can cut 2x of each - that is way cheaper on send-cut-send (afair only 25% extra for 2nd part).
- Animats 2y ago
  > plywood design. Coolant and plywood do not play well together.
  - sottol 2y ago