Genmitsu Router / Engraver

Sadly the MKS SERVO42C is substantially different from the earlier revisions that could use the GitHub - Misfittech/nano_stepper: Stepper feedback controller open source; also, as far as I can tell, MKS didn’t follow the GPL for their A and B revisions; they may or may not have started over completely from scratch for the C revision but it appears unlikely that they did.

Similarly, the BIGTREETECH S42C does not appear to have open source support, though the A and B revs do.

Simple FOC does have stepper support and looks interesting.

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MKS is known for that, unfortunately, along with providing little or no support. Smoothie had issues with MKS controllers that were shipped with some form of smoothieware that they expected Smoothie to support for free. What ever happened with smoothie, anyway, seems it took so long that time passed it by.

Get updates at the smoothieboard v2 kickstarter page, after a lot of covid-caused troubles, we’re currently producing the v2 boards, and getting very close to final release.


Glad to see you’re still around! For a while there every time smoothie got mentioned in a forum you’d pop up in a few days with an enlightening comment

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I’m still around, but mostly on weekends nowadays.

Worldwide components shortage means no smoothie v1 productions, means no income, means I had to take a job (at, they are an awesome company. but it’s not smoothie-related). still working very hard on v2 on the weekends


sorry, slow replying. Yes, I think the plunge is too aggressive, but not sure how to change plunge speed versus retract speed in GRBL package

The 3018 is much better if I power the spindle from a separate power supply. I think there are two things:

  1. current available to drive steppers is probably higher
  2. smoothness of the spindle drive - the board on the 3018 has PWM control and you can see the DC motor arcing on the brushes, switch to benchtop power supply and the vibration levels drop significantly

Interesting as I had a similar experience with an old manual milling machine when I swapped from a geared head to a belt drive. Noise levels dropped, but also vibration of the tool reduced and I’m positive that the tool bits also lasted longer.

You change it in your CAM (gcode generating) software, not in grbl. Just like all cutting parameters, feed rate, spindle rpm (which), plunge, depth of cut, etc. It’s not necessary, or desirable, to be altering grbl settings for basic feeds and speeds.

I couldn’t find where you said what software you’re using, but these are often set by individual bit in your tool database


Hi Kirk, I’m using carbid create (v6) and this doesn’t appear to have acceleration. I can set a limit in GRBL Candle, but that is just one value. It would be best I think if I could set a different rate for plunge and retract that is different to X/Y
Maybe I need to try different software.
Best regards, Nigel

@stewart’s Kiri:Moto has separate Z feed and XY feed.

FreeCAD Path Workbench’s Tool Controllers have separate feed rates and rapid rates for horizontal and vertical moves. The primary maintainer of the FreeCAD Path workbench, Brad Collette (aka “sliptonic”) just started a new company around FreeCAD, Ondsel. I’m curious to see what comes of that; the company is “open core” (so will be doing some proprietary things) but FreeCAD itself is LGPL so changes to FreeCAD will be open source. They haven’t been too specific yet that I’ve seen about how the company will make money, though.

I’m surprised that carbide create doesn’t have this, to be quite honest. But then @Scorch’s F-Engrave doesn’t either, so maybe v-carving doesn’t normally care due to the typical 60° bit tip?


I use FreeCAD, but haven’t taken the step into outputting cnc files, it looked like a significant learning step

Kiri:Moto is, in my opinion, easier to get started with. I used it when I made my Mathematical rosette iron because it was the only thing I found that could really handle that part. I had tried with FreeCAD and it was too hard.

FreeCAD Path Workbench got more complex a while back (with FreeCAD 0.19 if memory serves) — all for good reasons, but yeah, getting everything set up now takes a lot more work. I actually have run aground on coming up with a good system for my tool crib, and perfect has become the enemy of good enough.

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You set the acceleration in grbl, per axis. It’s not something you’d normally change after tuning. Grbl is the firmware in the router controller, Candle is a gcode sender running on your PC. While Candle talks to grbl they are completely different. An unmodified 3018 will handle an acceleration of 500 on X and Y. It can go much higher, but the run time reduction going from 30 to 300 to 500 is very noticeable, think twice as fast. I ran the same 5 to 10 minute job over and over with different sittings, engineer’s disease, over 500 the machine worked but vibrated more than I liked, setting it higher didn’t make much of a time difference. The default 30 is abysmally low for the machine, but keep it there for now. Here’s the relevant grbl settings, scroll up or down in that page and you can find them all. As always make sure you have a backup copy, in a file or at least on paper, before changing any settings so you can get back. That Candle screenshot you showed is a shortcut way to change all 3 settings, the program will do the $12x=yyy commands for you but you trade ease for flexibility. I didn’t do much with Z but tweaking that will make much smaller overall changes.

In Carbide Create V6 you define the feed rates, rpm, etc. by tool in the tool database. For different materials you can copy an entire tool tree and rename it, for example Kirks Bits - Softwood to Kirks Bits - Hardwood. You then edit the relevant settings for the new material. The later CC versions have video documentation (because it wastes more time and is harder to use than paper?). Chapter 11 in the link is how to create and modify your tool settings

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Thanks all for the hints and superb level of knowledge. I’ve made some changes and have some more to do, will do a roundup of everything and update you all.

Based on your comments it feels like the machine is moving forward in capability.

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