Can anybody please suggest possible things to check, or what might be wrong?
I have each axis driven by a NEMA23 motor (Stepper-online 23HS45-4204S) with a TB6600 driver. The X and the Z axes work great, but the Y just judders back and forth, regardless of which direction it is meant to be moving.
There are four stages: TB6600 driver, connector from control box to CNC frame, frame wiring, and stepper motor.
Normal connections:
X driver + X connector + X frame wiring + X motor = correct X movement
Y driver + Y connector + Y frame wiring + Y motor = Y juddering
Z driver + Z connector + Z frame wiring + Z motor = correct Z movement
Swapped one component:
X driver + Y connector + Y frame wiring + Y motor = Y juddering
Y driver + X connector + X frame wiring + X motor = correct X movement
Swap another component:
X driver + X connector + Y frame wiring + Y motor = Y juddering
Y driver + Y connector + X frame wiring + X motor = correct X movement
This implies the problem lies with either the Y frame wiring or the Y motor.
Changing the frame wiring requires some disassembly and desoldering, so is possible but not something to be undertaken lightly.
With the motor disconnected, the resistance across each coil is about 1 ohm, which is correct. The coils are not connected, or at least the resistance between the coils is above what my multimeter can measure, again correct.
When the motor is connected to the driver, but not powered, the resistance between the Y coils is 15K-ohms, but it is only 10K-ohms on the other two motors, which is odd. It does not matter which driver is connected to which motor.
When connected normally, there is continuity from the four motor wires all the way back to the driver outputs.
Another possibility is the connection could be intermittent, which tests fine but opens or shorts when moving.
Another possibility is a physical hang-up, although this is unlikely to create problems with both Y motors in the same way, so this might be eliminated.
Thank you both. After testing every joint in the Y link, make that MOSTLY connectivity from end to end. There was a dry solder joint but the springiness of the wire kept it in place when everything was stationary. I suspect that the motor movement nearby bounced the connection up and down.
Hi, I’m a new to posting so apologize in advance. Thanks for the awesome machine and all the support given through this forum.
This thread seems to most accurately resemble the challenge I have hit with the MPCNC I’ve built.
I have a RAMBO 1.4, and I’m using the V1CNC_Rambo_Dual (I think the one prior to the latest release).
1.) Z1 (up/down) seems to judder at around the same place, I have swapped the motor to Z2 to check cables and motor and the same thing seems to happen.
1.1.) I have visually checked the connector (it is the original motor cable) by taking it out of the plug and inspecting and nothing seems out of place. These motors have really not done any work so I can’t imagine any damage has happened since the build. The motor in previous tests has been fine.
2.) I wired the motors up to the diagrams I found on the website, but it seems that Y2 had to be moved to the X2 position.
3.) I have noticed in other posts that if using Dual End Stoppers you need the switches connected, but mine seems to run without them, so I’m pretty sure I have not made all the configuration changes correctly.
3.1.) It seems the End Stops are configured to use the XMax for the z2 sensor as well which confused me because there is a plug in the RAMBO to accept two Z sensors.
The two Z plugs are not supposed to be used for the two Z motors because then the motors are effectively wired in parallel. This cuts the current (and torque) in half in the best case, which can cause skipped steps, which from the video looks like what you have. Also lube on the lead screw and not overtightening the leadscrew nuts can make a big difference so worth checking but I have no evidence that those are a problem.
So instead of using the second Z plug, you need to use the “E1” for the second Z motor, just as you used “E0” for the second Y motor.