NEMA 17 0.9 or 1.8 degree ?

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chris_ma
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by chris_ma »

Adalbert wrote:
Thu Dec 23, 2021 1:24 pm
I use a common power supply 12V for Arduino and motor, therefore I would need a motor with 12V.
looks like that limits your choice considerably.
why not use two separate power supplies, or use a 24V one and a 12V step down convertor to hook up the arduino to that?
chris

Adalbert
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by Adalbert »

why not use two separate power supplies
I try to keep my setup as small and simple as possible.
That would not fit with this concept.

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Re: NEMA 17 0.9 or 1.8 degree ?

Post by rjlittlefield »

Adalbert wrote:
Thu Dec 23, 2021 12:00 pm
So, I have searched for a good one but I have found only this “funny” one
with 2A and 24V and very low holding torque.
https://www.digikey.de/de/products/deta ... 8/11564499?
ray_parkhurst wrote:
Thu Dec 23, 2021 1:07 pm
Can your controller do 24V?
I'm a little confused by the specifications.

Along with 2A and 24V, the spec says "Coil resistance 0.7 ohms". At steady state, 2A at 0.7 ohms is only 1.4V. So, I'm thinking that "24V" is actually a specification of maximum voltage applied to quickly overcome inductance. If that's the case, then it seems like a 12V controller would still work OK, just with a slower speed limit.

Am I missing something here?

--Rik

chris_ma
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by chris_ma »

that would probably work.
If one needs a motor with optimal specs and performance, it seems to me the more logical choice to choose the motor first and adapt the power supply to that though.
chris

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Re: NEMA 17 0.9 or 1.8 degree ?

Post by ray_parkhurst »

rjlittlefield wrote:
Thu Dec 23, 2021 1:47 pm
I'm a little confused by the specifications.

Along with 2A and 24V, the spec says "Coil resistance 0.7 ohms". At steady state, 2A at 0.7 ohms is only 1.4V. So, I'm thinking that "24V" is actually a specification of maximum voltage applied to quickly overcome inductance. If that's the case, then it seems like a 12V controller would still work OK, just with a slower speed limit.

Am I missing something here?

--Rik
I missed that very low resistance spec. Most others in the series are 10-12 ohms. Not sure why that motor (and only that one) has such low resistance.

Edited to add: here's the Lin catalog for 417 Series: https://www.linengineering.com/products ... 417-series

Edit 2: In that series, I'd personally choose the 417-09-03

Adalbert
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by Adalbert »


ray_parkhurst
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by ray_parkhurst »

Adalbert wrote:
Thu Dec 23, 2021 2:42 pm
What about 417-15-08 ?
https://www.linengineering.com/products ... /417-15-08
That's the one with the low resistance, pretty high torque, and 24V rating for unknown reason.

Edited to add: I chose the 417-09-03 because it has low torque, and low torque motors tend to microstep better. I am completely unsure how well any of these "24V" motors might work at 12V.

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Re: NEMA 17 0.9 or 1.8 degree ?

Post by rjlittlefield »

ray_parkhurst wrote:
Thu Dec 23, 2021 2:46 pm
I am completely unsure how well any of these "24V" motors might work at 12V.
Some guidance on that may be provided by the Torque Curves section of https://www.linengineering.com/products ... 417-series .

Below the graph is a set of fields into which values can be placed. If I try plugging in some ludicrously small value for voltage, then I get the error message "Should be greater 5 VDC and be less 80 VDC". Between those values, I see no change to the curves except for the labels on rotation speed, which seem to change linearly in proportion to supply voltage.

As I see the interface, the 417-15-08 holds out well to beyond 1000 rpm at 12V. The 417-09-03 looks good to beyond 500 rpm at 12 V.

--Rik

physicsmajor
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by physicsmajor »

These currents specified are max RMS and the voltage - so long as you're a few times over the nominal steady state suggested by the actual coil resistance (V = IR) at voltage set point - is immaterial.

Virtually all stepper drivers are "chopper" type and at the risk of oversimplification, they can be thought of as approximating constant current supplies during switching, i.e., they don't care about the voltage so long as it's "enough" to drive the current they want into the motor. Higher supply voltages, above and beyond "enough", allow you to go faster and are generally quieter. You can likely run with current substantially below the max spec.

Most people are interested in a lot of torque, at speeds which are stupidly fast from our perspective. Even 'slow' 3D printing for example is practically light speed to our macro rails. They are assuming you are going to use these motors to do something like this (that machine is using 4x 0.9 degree 2A NEMA 17 stepper motors, with a 24V power supply, and the video is realtime): https://www.youtube.com/watch?v=LDrulFDEXtM Obviously our purposes are the opposite extreme where we want small precise moves but with enough torque so no steps get skipped and things stay put.

Adalbert
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by Adalbert »

Hi Rik,
Below the graph is a set of fields into which values can be placed. If I try plugging in some ludicrously small value for voltage, then I get the error message "Should be greater 5 VDC and be less 80 VDC". Between those values, I see no change to the curves except for the labels on rotation speed, which seem to change linearly in proportion to supply voltage.

As I see the interface, the 417-15-08 holds out well to beyond 1000 rpm at 12V. The 417-09-03 looks good to beyond 500 rpm at 12 V.
great, many thanks for the hint!

Best, ADi

Adalbert
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by Adalbert »

Hi,
Obviously our purposes are the opposite extreme where we want small precise moves but with enough torque so no steps get skipped and things stay put.
Yes, I am looking for one where no steps are skipped. Namely for this solution:
viewtopic.php?p=277902#p277902
Image
Best, ADi

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Re: NEMA 17 0.9 or 1.8 degree ?

Post by ray_parkhurst »

Yes, our application is very different from something like CNC or 3D printing, etc. Microstepping for those apps is done for smoothness and noise reduction, not accuracy.

ADi, driving a microscope fine focus knob requires low operating torque, and zero detent torque, so one of the Lin's new Z series motors might work very well to get high microstep accuracy. Here is the one that seems to fit best:

https://www.linengineering.com/products ... Z417-11-03

Adalbert
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by Adalbert »

I had intended to ask Trinamic support which motor best fits the TMC5130
and meets my requirements, but they are now on holiday :-)

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Re: NEMA 17 0.9 or 1.8 degree ?

Post by ray_parkhurst »

One nice thing about that Lin Z motor is that the zero detent torque will give the fine focus knob a "normal" feel, ie it will have smooth operation rather than "clicking" between motor detents when you use the knob manually.

physicsmajor
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Re: NEMA 17 0.9 or 1.8 degree ?

Post by physicsmajor »

I'd love to play with a few of those Z417 motors but can't find anywhere to buy them.

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