DIY 5 axis stepper motor hookup problems.


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Thread: DIY 5 axis stepper motor hookup problems.

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    Default DIY 5 axis stepper motor hookup problems.

    Hi, ive built a few cnc machines before and have repaired many times. For some reason im running into problems wiring 1 motor for my 5 axis build. The motor is a nema 23 425oz motor that rotates the B axis of a BC head. Im using this stepper driver https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1. set at 6400 pulses/rev and 3.4 amps.

    So the problem is I cant get the wiring right, ive pretty much tried about 30 wiring combinations for A+A-B+B- with the Red black blue green leads from the motor. Some combinations will allow the motor to pulse and rotate correctly, but hold very little torque, I can turn with my hand without trying. This is the main problem, is that its not holding torque. I can get it to rotates correctly with jogging, but cannot get it to hold torque. ive tried wiring the motor to the driver outside of the main wiring harness and it results the same so its not a bad wire. Ive tried a different stepper driver and its the same thing. ive tried a different stepper motor and same thing, one stepper motor with a red green blue yellow lead on it worked and held torque after initially having the same symptom before I changed the wire combination. Im basically out of ideas as ive tried many combinations for wiring. many of them worked in rotating for jogging but still held no torque.

    Below are some pictures.

    Similar Threads:
    Attached Thumbnails Attached Thumbnails DIY 5 axis stepper motor hookup problems.-20190403_210302-jpg   DIY 5 axis stepper motor hookup problems.-20190403_210302-jpg   DIY 5 axis stepper motor hookup problems.-20190403_210315-jpg   DIY 5 axis stepper motor hookup problems.-20190403_210322-jpg  



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    Member orgreen's Avatar
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    Default Re: DIY 5 axis stepper motor hookup problems.

    Hi there, not nearly as experienced as you but just a thought, have you tried reducing the microstepping to a lower number?
    I've read that torque is negatively effected by high microstepping..

    Looks like an amazing build!

    Sent from my SM-G955F using Tapatalk



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    Quote Originally Posted by orgreen View Post
    Hi there, not nearly as experienced as you but just a thought, have you tried reducing the microstepping to a lower number?
    I've read that torque is negatively effected by high microstepping..

    Looks like an amazing build!

    Sent from my SM-G955F using Tapatalk
    Ill try it. Thanks



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    Default Re: DIY 5 axis stepper motor hookup problems.

    Hi - Firstly attach A to A and B to B to make sure they are the correct wires on the motor. With these connected you should not be able to turn the motor. Can do the same with an ohmmeter check that A & A are connected and B &B are connected ie they are the one winding. Once your sure you know which are the windings (as often the colours on the diagram are not what the motor has or is!!) connect A to A and B to B on the controller.

    Another way is if you have a motor that you know the A-A and B-B wires connect these to the unknown motor and if you turn the known motor the unknown motor will turn if its correctly wired. maybe it turns backwards in which case reverse one of the wires.

    I have used the DM542T a few times with no issues. Use the lowest pulses per rev that gets the job done. Usually 3600 pulses per rev is a good one as this matches the mechanical accuracy of a 200 step/rev motor. Good Luck, its an interesting build...Peter



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    Default

    I have heard that if you disassemble and reassemble a stepper motor that its never the same, a lower torque.
    Something to do with demagnetizing, obviously a factory figured it out and maybe a small voltage applied to both coils and a jig to remove the rotor at controlled rate
    I wish i knew more about that.

    Wisdom results from foolishness!


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    Default Re: DIY 5 axis stepper motor hookup problems.

    Thank you for your suggestions. Peeteeng ill try what you have suggested, but for now Ive tested the motor in many different ways, and its just telling me that the 425 oz motor isn't strong enough to hold torque as I apply a load to it from a lever (10 inches from the shaft). But its my understanding that a 425 oz motor should be able to hold 26 pounds 12 inches from its shaft. It just doesn't seem like its suppose to be that weak. ive tested other drivers and other working 425 oz motor, putting a vice grip on the shaft and turning it and it also seems weak. So im conceding that the 425 oz motors are weak relative to what I want to use them for. I hope im wrong and someone can correct me.


    Anyhow, a solution to this is if I use the 425 oz motor with a 5:1 gear reduction. I have one on hand. That should give me enough torque im looking for. However, the gear reduction box has a lot of backlash. Up to 3/32" 10 inches out from the shaft. When the C axis is turned 90 degrees, the tip of the bit could be around 14 inches from the shaft. this would cause it to have a backlash of about 1/8". Would compensating for this in mach 3 and steps per revolution be reasonable to do or is this just something that mechanically has to be fixed.


    Also to clarify on the backlash compensation in mach 3. For every line of code, does mach 3 initialy jog the backlash out first then runs the code. so it would jog the backlash out, stop, then start jogging with no backlash compensated. is that correct? or can someone explain to me how it works? thanks.

    Last edited by Ncrazyballa; 04-06-2019 at 11:19 AM.


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    Default Re: DIY 5 axis stepper motor hookup problems.

    But its my understanding that a 425 oz motor should be able to hold 26 pounds 12 inches from its shaft.
    It's oz-in, not oz-ft.

    26lbs 1 inch from the shaft.
    2lbs when 12 inches from the shaft. Best case scenario

    Gerry

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    Default Re: DIY 5 axis stepper motor hookup problems.



    Got my answer with this video in terms of backlash compensation.
    So my solution will be to use the 425 oz motor with a 5:1 gear reduction for proper torque, and set backlash to compensate for the backlash in the gear reducing mechanism. Thanks for all inputs its much appreciated. If I have any more questions ill post here.

    - - - Updated - - -

    Quote Originally Posted by ger21 View Post
    It's oz-in, not oz-ft.

    26lbs 1 inch from the shaft.
    2lbs when 12 inches from the shaft. Best case scenario
    Thanks! it makes sense now.



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    Default Re: DIY 5 axis stepper motor hookup problems.

    Hi, I have more wiring problems to figure out. This one is for an 8 lead nema 34 stepper driving the Z. Tried wiring it according to diagrams but im still getting a red light at the driver. With the leads disconnected from the driver its a green light so its likely incorrect wiring. I used a multimeter to check which leads from the motor were attached to a coil. Odd thing is that all wires are giving me continuity for the other 7 wires. so all 8 wires are connected. some how. here is a link to a video of that. Anyone have any idea if that's normal or can explain that? thanks.



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    Default Re: DIY 5 axis stepper motor hookup problems.

    8 wire should have 4 coils so 4 circuits. Seems you have an internal short? Is the motor brand new? Peter

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    Default Re: DIY 5 axis stepper motor hookup problems.

    motor is absolutely new.



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    Default Re: DIY 5 axis stepper motor hookup problems.

    you can still check the Ohm resistance between the wires. The coils are normally a few Ohm. If it's all low Ohm value between the wires, than it's almost sure you have a bad motor ( with shorts )
    These motors should have 4 separate coils just as Peteeng says.



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DIY 5 axis stepper motor hookup problems.

DIY 5 axis stepper motor hookup problems.

DIY 5 axis stepper motor hookup problems.