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If you're interested in Open-Source CNC you should check out two of my Open-Source projects. https://camotics.org/ https://camotics.org/ a CNC simulator and ht

If you're interested in Open-Source CNC you should check out two of my Open-Source projects. https://camotics.org/ https://camotics.org/ a CNC simulator and https://buildbotics.com/ https://buildbotics.com/ a CNC controller. I'm somewhat surprised neither of these were mentioned.

phkahler 8y ago
Do any of them support the arc or spline gcode? I noticed that most of the 3d printers do not, even though they are essentially 4-axis CNCs.
- Ccecil 8y ago
  3d printers typically don't care about arcs or splines since they only use STL files which do not have "real" curves. Some firmwares support arcs (smoothieware, which is based on GRBL) but it still breaks the arcs down to segments.
  - phkahler 8y ago
    >> 3d printers typically don't care about arcs or splines since they only use STL files which do not have "real" curves. I would have thought the printer would support arcs even if the slicer doesn't. There is work going on to support arcs in slic3r (automatic detection of arcs) but it will be irrelevant for printers that don't support it. It's would also be possible for a slicer to import step files and find such surfaces. One can also approximate other curves with fewer gcodes if they use arcs vs lines - splines even fewer.
    - Ccecil 8y ago
      Some of the firmware versions do have G2/G3 in them but not all. http://smoothieware.org/supported-g-codes http://smoothieware.org/supported-g-codes I assume most of the modern ones do but some of the older 3d printing firmware use a very butchered version of the gcode "standard" which eliminate or rename many of the unused codes.
    - dwild 8y ago
      I just flashed my Ender 3 using the latest Marlin version and I deactivated ARC support manually on it to save space. Considering how pretty much all 3D printers use a Marlin firmware, seems like ARC is supported pretty much everywhere.
- jcoffland 8y ago
  G3 and G4 arcs are supported but not splines. It would be easy to add spline support but there is very little demand for them. Since I released CAMotics in 2011 no one has asked for spline support.
Hasz 8y ago
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.
- jcoffland 8y ago
  No servo support yet but we can drive NEMA 23s and 34s at up to 4k RPM. Edit: We are adding step and direction outputs which could be used to control an external servo driver. You can actual access these outputs now of you are alright with soldering some headers on to the main board. In the future, we do plan to make a servo version of the Buildbotics CNC controller.
- semi-extrinsic 8y ago
  FYI there are hybrid steppers now, which helps with some of the traditional stepper drawbacks. See e.g. https://youtu.be/NARodU-vVWs https://youtu.be/NARodU-vVWs
- dekhn 8y ago
  can you point to some continuous rotation servos that would replace steppers? I haven't been able to find any that are affordable.
  - HeyLaughingBoy 8y ago
    I believe he means servos as "high-speed DC brushless motors with feedback" not the low cost gearmotor servos used in R/C models.
    - dekhn 8y ago
      but those aren't affordable! also you can buy steppers with feedback in NEMA34+ form factor for not too much. I use them in my machines.
    - aj7 8y ago
      It is about $1000 an axis for 1/2 hp AC servo + amplifier from China. But worth every penny. Some productive work can be done with bigger step motors. But setups with little ones are soon abandoned.
toss1 8y ago
Cool -- just took a quick look, downloaded and I'll be trying it out soon -- thanks!
juliangoldsmith 8y ago
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.
- kazinator 8y ago
  Wild assed guesses: Damage/safety issues: operating the milling machines incorrectly, or in an untimely manner. Related to latter point: lack of hard real-time processing in the upstream software?
  - DannyBee 8y ago
    1. You can do SIL-* in software. 2. See, e.g., beckhoff :) (Both are these are solvable, it's interfacing with the machine in any standardized way that is not)
- semi-extrinsic 8y ago
  The gcode emitted by CAM software is quite literally the assembly code of CNC machines. Your question is somehow similar to "why can't the C code directly control the CPU"?
- rmu09 8y ago
  CAM can take a lot of time and need considerable computing resources. Not that much of issue today, but still, why do the same computations over and over again? Also, you will want to inspect the toolpaths before running them on real hardware.
  - juliangoldsmith 8y ago
    Yeah, you'd still definitely want to look at the toolpaths. As far as recalculating everything, it could still calculate most of it ahead of time. What I'm thinking of is something like a CAM workspace in FreeCAD. That is, something like would let you take your model, generate and inspect a toolpath (or flip through possible toolpaths), and produce a part. The CAM software would get feedback from the controller, so it could follow what was going on. It might also be possible to make adjustments, or pause the run, based on sensors. For instance, if you could detect chatter, you could slow down the feed rate; if you could detect a broken tool, you could pause the run and ping the operator.
joshu 8y ago
Camotics is wonderful, thanks! I did have some problems testing some super complicated toolpaths (millions of lines long) though...

phkahler 8y ago

Do any of them support the arc or spline gcode? I noticed that most of the 3d printers do not, even though they are essentially 4-axis CNCs.

Ccecil 8y ago
3d printers typically don't care about arcs or splines since they only use STL files which do not have "real" curves. Some firmwares support arcs (smoothieware, which is based on GRBL) but it still breaks the arcs down to segments.
- phkahler 8y ago
  >> 3d printers typically don't care about arcs or splines since they only use STL files which do not have "real" curves. I would have thought the printer would support arcs even if the slicer doesn't. There is work going on to support arcs in slic3r (automatic detection of arcs) but it will be irrelevant for printers that don't support it. It's would also be possible for a slicer to import step files and find such surfaces. One can also approximate other curves with fewer gcodes if they use arcs vs lines - splines even fewer.
  - Ccecil 8y ago
    Some of the firmware versions do have G2/G3 in them but not all. http://smoothieware.org/supported-g-codes http://smoothieware.org/supported-g-codes I assume most of the modern ones do but some of the older 3d printing firmware use a very butchered version of the gcode "standard" which eliminate or rename many of the unused codes.
  - dwild 8y ago
    I just flashed my Ender 3 using the latest Marlin version and I deactivated ARC support manually on it to save space. Considering how pretty much all 3D printers use a Marlin firmware, seems like ARC is supported pretty much everywhere.
jcoffland 8y ago
G3 and G4 arcs are supported but not splines. It would be easy to add spline support but there is very little demand for them. Since I released CAMotics in 2011 no one has asked for spline support.

Hasz 8y ago

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.

jcoffland 8y ago
No servo support yet but we can drive NEMA 23s and 34s at up to 4k RPM. Edit: We are adding step and direction outputs which could be used to control an external servo driver. You can actual access these outputs now of you are alright with soldering some headers on to the main board. In the future, we do plan to make a servo version of the Buildbotics CNC controller.
semi-extrinsic 8y ago
FYI there are hybrid steppers now, which helps with some of the traditional stepper drawbacks. See e.g. https://youtu.be/NARodU-vVWs https://youtu.be/NARodU-vVWs
dekhn 8y ago
can you point to some continuous rotation servos that would replace steppers? I haven't been able to find any that are affordable.
- HeyLaughingBoy 8y ago
  I believe he means servos as "high-speed DC brushless motors with feedback" not the low cost gearmotor servos used in R/C models.
  - dekhn 8y ago
    but those aren't affordable! also you can buy steppers with feedback in NEMA34+ form factor for not too much. I use them in my machines.
  - aj7 8y ago
    It is about $1000 an axis for 1/2 hp AC servo + amplifier from China. But worth every penny. Some productive work can be done with bigger step motors. But setups with little ones are soon abandoned.

toss1 8y ago

Cool -- just took a quick look, downloaded and I'll be trying it out soon -- thanks!

juliangoldsmith 8y ago

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.

kazinator 8y ago
Wild assed guesses: Damage/safety issues: operating the milling machines incorrectly, or in an untimely manner. Related to latter point: lack of hard real-time processing in the upstream software?
- DannyBee 8y ago
  1. You can do SIL-* in software. 2. See, e.g., beckhoff :) (Both are these are solvable, it's interfacing with the machine in any standardized way that is not)
semi-extrinsic 8y ago
The gcode emitted by CAM software is quite literally the assembly code of CNC machines. Your question is somehow similar to "why can't the C code directly control the CPU"?
rmu09 8y ago
CAM can take a lot of time and need considerable computing resources. Not that much of issue today, but still, why do the same computations over and over again? Also, you will want to inspect the toolpaths before running them on real hardware.
- juliangoldsmith 8y ago
  Yeah, you'd still definitely want to look at the toolpaths. As far as recalculating everything, it could still calculate most of it ahead of time. What I'm thinking of is something like a CAM workspace in FreeCAD. That is, something like would let you take your model, generate and inspect a toolpath (or flip through possible toolpaths), and produce a part. The CAM software would get feedback from the controller, so it could follow what was going on. It might also be possible to make adjustments, or pause the run, based on sensors. For instance, if you could detect chatter, you could slow down the feed rate; if you could detect a broken tool, you could pause the run and ping the operator.

joshu 8y ago

Camotics is wonderful, thanks! I did have some problems testing some super complicated toolpaths (millions of lines long) though...