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Topic: NEMA-17 Bipolar + Adafruit Motor Shield v2 (Read 4399 times) previous topic - next topic

SyFr

Nov 21, 2013, 12:10 pm Last Edit: Nov 21, 2013, 12:11 pm by SyFr Reason: 1
Hi,

I am looking for a high resolution stepper motor to be controlled with an Arduino (step angle should be <<0.1°) and found this motor+gearbox which seems to fit which offers 0.018° (at 12V, 1.7A rated current): http://www.phidgets.com/products.php?category=23&product_id=3319_1

I have planned to controll the motor with an Adafruit Motor Shield v2 (with 1.2A current capability according to the specs with 3A peak): http://www.adafruit.com/products/1438#Description

The motor will progress at approx. 1 step/second. Has someone experience with this combination? Are there potential problems? Is there a better solution?

Regards,

dc42

For that stepper motor (and most modern bipolar steppers), you will get much better results from a chopping-type stepper motor driver, rather than a generic motor driver that is designed to drive DC motors. For example, this one http://www.pololu.com/product/2133.
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SyFr

#2
Nov 23, 2013, 07:29 am Last Edit: Nov 23, 2013, 08:10 am by SyFr Reason: 1
Thanks for your reply! I will give this controller a try as well.

MarkT

Are you sure that motor's of use to you, the backlash error in the gears is a whopping
3 degrees!
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SyFr

#4
Nov 23, 2013, 01:03 pm Last Edit: Nov 23, 2013, 02:04 pm by SyFr Reason: 1
I completely missed that. But the backlash error happens only if I change the rotation direction and not when the step direction is the same?

For my usecase I need accurate positioning for each step in one rotation direction (step-wise-"endless" rotation in one direction).

MarkT

#5
Nov 24, 2013, 12:41 am Last Edit: Nov 24, 2013, 12:43 am by MarkT Reason: 1
Yes, backlash depends on reversal, but if its 3 degrees you won't be getting 0.018
degree accuracy under varying load even for the same direction, its just not a precision
cut gear.

For 1 minute of arc accuracy you are talking a precision turntable with anti-backlash
worm-drive probably...

Or do you only need 1 minute precision?  What are you trying to do?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

SyFr

#6
Nov 24, 2013, 08:15 am Last Edit: Nov 24, 2013, 08:19 am by SyFr Reason: 1
The motor should move a rotating plate on which a laser-based device is attached which takes measurements. The weight of the device is approx. 3.5kg. The plate can be mounted flat or up to 45° horizontal angle.

The plate should be moved by a constant adjustable angle A around the rotation axis, then stops, takes a measurement, and increases it's position by A again. This angle A is set before the process is started and should be in the range of arc minutes, or even better arc seconds. It is ok if the angle A is a multiple value of the minimum setable angle by the motor/gear set (for instance if the minimum motor step is 0.01° then 2*0.01, 3*0.01, etc. are fine).

Do you have recommendation for another motor/gear set with a similar price?

SyFr

I just tested the motor with the Adafruit board and burned one driver chip on the board. It seems to weak for motor.

SyFr

The DRV8825-based stepper driver proposed above works very well. Thanks for the hint!

dc42


The DRV8825-based stepper driver proposed above works very well. Thanks for the hint!


Thanks for the feedback!
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

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