Any tips on tuning the steppers on a printrboard (Rev.

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(John Davis) #1

Any tips on tuning the steppers on a printrboard (Rev. D) with a multimeter? I followed this video originally:

http://youtu.be/BPU0vL-VQl0

But couldn’t figure out where he got the value of 1.45V and it made my motors very loud if I set the pots that high.

After searching around a bit I found this seemingly sensible blog post on the subject:

I looked up the specs for my Kysans (1124090) and found them to be rated for 1.5A per phase and when I solved for Vref using the formula on Erl’s page (and 0.11 ohms for the sensing resistance) I get 1.32V, which still makes my motors a little loud and quite hot if I set the pots that high.

Am I going about this wrong? Any advice? Thanks!

(Stephanie A) #2

I like to set it by feel and sound. Turn the pots down, then slowly turn it up until the motors move. Turn it a little bit past that, and you’re done. Test with a few movements, if it stalls, turn it up a little more.

(John Davis) #3

Yeah, that’s what I did originally, but I’m kind of partial to repeatability and particularly fond of putting a number to stuff (when possible) and it seems like there should be a way to do this “properly”, you know?

(Stephanie A) #4

Well, you can do that method, then read the voltage and set all the rest. Besides, I think the amperage is max operating current, it might be better to run lower, say at 80%. Try that and see. 1.07v perhaps.

(Igor Larine) #5

I usually try to stick to around 1 V - 1,45 sounds like it would make the motors scream. The principle of motor usage in 3D printers is underfeeding them :slight_smile:
My tuning begins as @Stephanie_A suggests, then you just have to see how your motor performs during a print. If it skips - turn it up a bit, if it overheats - lower a bit. Monitor the temperature of the driver at the same time - 1,45V would make the chips hot even on idle.

(John Davis) #6

Thanks to you both for your comments. I’m really hoping to scare up someone with the electrical engineering know-how to teach me a theoretical/practical way to do this. For example, if my X or Y axis has resistance that is being overcome by excessive voltage to the steppers, isn’t it possible I’m also overpowering the micro-stepping?

(Rob .__) #7

Not sure if you have seen this or not as it has been a while. http://www.printrbottalk.com/forum/viewtopic.php?f=6&t=1975

(John Davis) #8

Yes, that’s the Erl that wrote the blog post I referenced.