A couple of days ago,

3D Printing
,
1

A couple of days ago, I mentioned here I was using cheap chinese TB6600 drivers from ebay.
At first, everything seemed to works just fine.
But lately I got the feeling these drivers were not delivering the power I expected.
My extruder still seemed a little underpowered.
So I decided to measure the current running through my steppers.
I had adjusted the dip-switches to limit the current to 2,5 A.
But the current never exceeded more than 1 A.
A quick search on the internet solved the problem. The driver chips are, due to a faulty design of the printboard, limited to 30% torque.
Only after connecting pin 24 with pin 3 of the stepper driver, the torque is at 100%. The difference in power is staggering.
There is no way I can stop my extruder by holding the big gear with my bare hands. Before this, I could easily make the extruder skip almost by looking at it
So, if any of you are considering these drivers, be sure to make this adjustment.
But I also have a question. My stepper motors are rated for 2,5A.
Is this total current (two coils) or current per coil?
My steppers get quite warm now.

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2

Generally, stepper motors are rated per coil: 2.5A flows through each, so if you’re half-stepping you’ll see 5 amps total for half the steps.

3

@John_Bump
you’ve got me a little confused now. I don’t understand what half-stepping would do for the amperage. But I measured 2,5 amps in 1 coil, so if I understand you correctly, that should be okay?

4

Yes, it’ll do great. Full step means power to coil one, in one direction, power to other coil, in one direction, power to first coil in reverse direction, and so forth. Half step means power to coil one, then while still putting power through that coil, power through coil two – hence, twice the amperage, and the rotor is halfway between the coil 1 and coil 2 positions. It doubles your steps, but means half the time you have both coils drawing current.