How much current to NEMA 17?

Hi, I was just wondering how much current people with Nema17 and a prusa i3 or similar model are using, I was running mine at 1.53amps but I lowered to 1.33amps and it is still working fine. I would like to know how low you have yours.

It depends on model of the stepper motor you are using.

not all nema 17's are the same. (apart from their X and Y dimensions which is what nema 17 means (1.7 x 1.7 inch (43.2 x 43.2 mm) across the face)

Anywhere from 0.5 to 2 amps. Since it was running at 1.5 its likely a higher rated one.
Current rating is related to price, cheaper is usually less current capable.
You could email them, or look up the number of the motor.
I am sure Prusa will tell you if they know(they should).

The idea is to tune them to the lowest current that does not cause skipped steps (to run cooler), but they can run safely to pretty warm temps.

In my experience re-invigorating the SmartRap Mini, there are a number of different types of tests you need to run to make sure its not skipping. i.e. a test cube might work great, but a full plate, or a large part, or a complex part might fail at some point.

Enough plus 10% margin while being conservative by staying at less than 10% of the max.

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"A comical prototype doesn't mean a dumb idea is possible" (Thunderf00t)

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orbitalair
Anywhere from 0.5 to 2 amps. Since it was running at 1.5 its likely a higher rated one.
Current rating is related to price, cheaper is usually less current capable.
You could email them, or look up the number of the motor.
I am sure Prusa will tell you if they know(they should).

The idea is to tune them to the lowest current that does not cause skipped steps (to run cooler), but they can run safely to pretty warm temps.

In my experience re-invigorating the SmartRap Mini, there are a number of different types of tests you need to run to make sure its not skipping. i.e. a test cube might work great, but a full plate, or a large part, or a complex part might fail at some point.

My y-axis stepper was really hot, I couldn't touch it for more than 2 seconds or I'll get burned, I have nothing decent to measure the temperature, but I assume that's too hot.

Yes I would consider that too hot.
50C is pretty warm, but wont burn you, iirc many motors are rated to 80C, depends on the manufacturer.

Do you have a heated bed? set it to 40 or 50C and compare. Subjective of course, but close.

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orbitalair
Yes I would consider that too hot.
50C is pretty warm, but wont burn you, iirc many motors are rated to 80C, depends on the manufacturer.

Do you have a heated bed? set it to 40 or 50C and compare. Subjective of course, but close.

I use my heatbed at 70C, I guess my stepper was at 100C or something, I reduced it's current from 1.53 to 1.33, so that should yield about 20% less heat(using the squared rule), but I'm not sure that's enough, haven't tested it yet.

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vitorbrazil

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orbitalair
Yes I would consider that too hot.
50C is pretty warm, but wont burn you, iirc many motors are rated to 80C, depends on the manufacturer.

Do you have a heated bed? set it to 40 or 50C and compare. Subjective of course, but close.

I use my heatbed at 70C, I guess my stepper was at 100C or something, I reduced it's current from 1.53 to 1.33, so that should yield about 20% less heat(using the squared rule), but I'm not sure that's enough, haven't tested it yet.

My stepper is rated at 1.7amps btw

How did you determine the amperage your board was producing?

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etfrench
How did you determine the amperage your board was producing?

If you are talking about the current that your driver's are sending the steppers, I use a4988 drivers, so the basic formula is Current=Vref/0.8

Edited 1 time(s). Last edit at 02/16/2018 10:40AM by vitorbrazil.