Jan 21

J3

7 comments

Hey there!

 

I am Peter.

 

For this build, I am using AR2.0 s/w with Aluminum kit.

 

Working through the build, the J3 motor doesn't seem to move the arm much. The arm remains in the position of touching the J3 limit switch.

 

I even tried connecting J3 motor to the J2 motor wiring to see if I was able to "jog" J3 via J2 + - buttons but it had the same result - not much movement.

 

NOTE: With the system off, I am able to easily move the arm up and down. So, I can confirm that the arm joint is not stuck.

 

Any suggestions on the cause and fix?

what are your dip switch settings for microstepping? is the arm consistently moving a short amount? curious if one of the calibrations settings got goofed causing it to not move far.

Jan 21

J3 Dip switch : 1 and 5 are OFF. Others are ON.

 

To debug, removed the motor from the arm and "jogged" it using the AR2 2.0 exe file.

 

For moving +1 to +141, the motor teeth moved about 5 teeth.

When I manually move the arm, 5 teeth movement should bring up the arm almost straight up.

So, calculation seem right.

The motor teeth (on no load) seem to move right.

The arm seems to move easily (no tight bearings at the joint).

But, with the motor installed in the arm, it is not able to budge the arm much - low power?

Sorry, I am just thinking through the debug steps...

 

Btw, just noticed that J3 motor gets really hot - is this a problem/unexpected? The other motors seem okay.

 

thanks.

the motor should be fairly warm but not too hot to touch. is it making a groaning noise and not moving very far? if the drive doesn't sound consistent or is groaning rather than whining evenly then you likely have a wiring issue. only one pair of coils is driving the motor. I would check the JST connectors for bad connection as you may be missing one of the A+A- or B+B- wires.

Jan 22Edited: Jan 22

Thank you for your feedback. Responding to your question/feedback below.

 

*) the motor should be fairly warm but not too hot to touch.

A) Other motors were warm. J3 was hot.

 

*) is it making a groaning noise and not moving very far?

A) When I first connected J3, it was making a fairly loud hissing sound. Motor wasn't working at all. Other motors J1, J2, J4, J5 seem to be working. Upon checking J3, noticed that one of the pins of the motor wire was bent when I connected it to the JST connector. So, fixed the pin and reconnected. Do you think one or more of the J3 motor coils got burnt inside when I ran it with bent pin?

 

 

*) if the drive doesn't sound consistent or is groaning rather than whining evenly then you likely have a wiring issue. only one pair of coils is driving the motor. I would check the JST connectors for bad connection as you may be missing one of the A+A- or B+B- wires.

 

A) Good question. With all the wiring connections on (except the motor wire connected to JST), I ran connectivity check all the way from the servo drivers to the JST connectors - they connect as shown below, and without any cross connections. Do you think below is correct?

 

Found wire connectivity as follows -

Driver wire = JST connector (to the J3 motor)

 

WHITE = BLUE

BLACK = BLACK

RED = RED

GREEN = GREEN

 

 

 

 

Is your problem solved. If yes then please let me know what steps you took.

May 21

Hi Peter, I'll try and lend a hand but I certainly dont have a good understanding of what your problem is.

 

First of all I don't think you have burnt out your motor. I have had J4 run really hot a couple of times for a long time and it hasn't seemed to damage it. To be honest, I havent even pinned down why it does it but i wouldn't be too worried for now!

 

 

####The motor teeth (on no load) seem to move right.

####The arm seems to move easily (no tight bearings at the joint).

####But, with the motor installed in the arm, it is not able to budge the arm much - low power?

 

The motor is powerful enough so scratch that off the list (unless it is burnt out).

From the sounds of it I would double check that the spindle(?) from the motor isn't spinning from the gear. (ie; the motor is spinning but the gear is slipping). Easiest is just to use a marker a draw a line from the gear to the spindle and see if they stayed lined up.

 

If not, are the other pins set to the right level? They control how many steps they are and if they are set too high that could cause problems.

 

 

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