Min-rambo motor current settings

Hello all,

I have been reading through the driver math section on the mini-rambo but it does not make much sense to me. I am trying to find out how to properly find good motor current settings. Also are there other settings besides PWM_MOTOR_CURRENT that I can adjust to get better torque?

What is the issue you are trying to solve and what settings do your steppers need?

No. Skipping steps should not be an issue, most likely there are other things going one or you have very tiny steppers. How fast are your movements and rapid movements, did you build it to spec, what pulleys are you using, what is your use case?

Ryan I picked up a 5 pack of steppers on Amazon. They say that they are 2A 84oz.in steppers. I do still skip steps every once in a while. Machine was built to a 3’x2’ working area and im using 16 tooth pulleys for GT2 belt. I am running at 50mm/sec feed rate for 1/8" v-bit and round nose 3mm/sec plunge. Depth per pass .0625" at 40% stepover.

Edit: I have only cut wood so far, pine mostly. I am currently at 1.3A for my PWM_MOTOR_CURRENT.

8-15, is pretty normal up to maybe 20 on light stuff. If you need speed cut deeper. Faster speeds = less torque.


The quick a way to check you steppers is after 10-20 minutes of being energized and working they should be warm, not hot but warm. if they are not you need to give them more power. But my firmware should be pretty close to what you need.

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Thanks for the info. I will cut the speed down and work for deeper cuts per pass. What would you recommend for depth per pass to start with a feed rate of say 12mm/sec on soft wood?

Start here and check out some of my newer YouTube videos.


It may sound strange but you may want to try wiggling the wires attached to your steppers while it is moving around. If you hear it skip steps while you are touching the wires then you may have an issue with the wiring moving during the jobs. If the connection to the steppers is loose enough to compromise the circuit then they can skip. If you find this to be the case then you could find better ways to secure the wires.

I had this happen to me once on a Davinci 2 3D printer. The wire harness was zip tied to an anchor point but there was still a few micrometers of movement at the connection and that was enough to cause random skipped steps in either direction. I looped the wire harness and zip tied it twice and the problem was solved.

Since the steppers move around on these machines and the wires have to move with them I worry that may be an issue on occasion.