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can you point to some continuous rotation servos that would replace steppers? I haven't been able to find any that are affordable.
I believe he means servos as "high-speed DC brushless motors with feedback" not the low cost gearmotor servos used in R/C models.
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Yes. This article is about very low end CNC, just 2D routing. Using a Dremel tool as a CNC router never works very well. The motor isn't constant speed, slows way down under load, and can overheat. The bearings can't take side loads for long, either. It's been tried. A Bosch router from Home Depot works much better. Those can cut wood all day. You can take off the handles, leaving a motor cylinder that can easily be…
I have to repeat the points in this comment. I've worked extensively with low-cost CNCs, and they can't really do anything more than light engraving of aluminum and slow cutting of wood. There are some straightforward physical reasons for this (there is no cheap and fast replacement for mass and torque).
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Will you be adding servo support in the future? Steppers are great, but anything big needs a servo, as the steppers get to expensive and too slow very quickly.
can you point to some continuous rotation servos that would replace steppers? I haven't been able to find any that are affordable.
Anything bigger, many people seem to like ClearPath servos. Price to performance seem to be pretty good.
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A poorly programmed CNC machine can drill a gaping hole in itself, and into the table that it stands on. Don't ask me how I know. If there was no table, it would be the ground, and yes, it would . Not many things can stand in the way of a spindle hell-bent on chopping chips off a block of titanium. It's a very fun thing to play with, though. Probably the most high-stakes programming most of us are ever going to get.
Can the CNC machine computer not simulate the program and see if it violates some safety rules like cutting into the table or removing too much material at a time?
If you're interested in Open-Source CNC you should check out two of my Open-Source projects. https://camotics.org/ a CNC simulator and https://buildbotics.com/ a CNC controller. I'm somewhat surprised neither of these were mentioned.
Is there any reason why CNC machines aren't directly controlled by CAM software, beyond it always having been done that way? I'd think it would be useful to integrate the two, instead of the CAM software just firing-and-forgetting toolpaths.
I got into CNC milling about 9 months ago. SVG to 2.5D problems are easy, and get you to a lot of cute solutions, its about as close to the work flow of 3D printers as you can get. But the really interesting stuff is when you get to CAM. Multiple tool paths, genuine 3D cutting. Moving the work between paths etc. Its like going from juggling 3 balls (2.5d) to 5 balls (3D). I haven't seen any competitive opensource CAM…
to me the hard stuff is 5 axis with tool vectoring and collision avoidance.
If you're interested in Open-Source CNC you should check out two of my Open-Source projects. https://camotics.org/ a CNC simulator and https://buildbotics.com/ a CNC controller. I'm somewhat surprised neither of these were mentioned.
Is there any reason why CNC machines aren't directly controlled by CAM software, beyond it always having been done that way? I'd think it would be useful to integrate the two, instead of the CAM software just firing-and-forgetting toolpaths.
Earlier quoted context omitted.
I have to repeat the points in this comment. I've worked extensively with low-cost CNCs, and they can't really do anything more than light engraving of aluminum and slow cutting of wood. There are some straightforward physical reasons for this (there is no cheap and fast replacement for mass and torque).
You’re absolutely right. If you’ve been around industrial grade equipment, it’s painful to watch hobbyists fiddle with equipment that is not very productive, and soon abandoned.
Even though I love 3d-printing, and designing/building machines, I would not build a small CNC like that from scratch. Since you get better machines for <200 USD that runs open source firmware (grbl) out of the box. Recently got one of them for PCB milling, a CNC 3018 Pro
I've been eyeballing the CNC 3018 Pro for a few weeks now. I would appropriate any input you have on the device. Pros/cons/alternatives I should look at. Anything!
https://carbide3d.com/shapeoko/
:)
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It seems like the machine itself could implement some safety checks, like if a motor is commanded to go outside of its range of motion you trigger a stop with an error code and let the operator sort it out. Or go even more oldschool and have physical safeties on the machine that trip if your cutting tool attempts to exit the work area. I mean these aren't cheap machines, it seems like they could be engineered to be j…
Real CNC machines have limit switches, they monitor the load on the axis and spindle servos etc etc. But that doesn't prevent running your cutter into a fixture at positioning speed and ruining the spindle bearings.