I’m using a Ultimachine RAMBO 1.4 so each motor has its own socket on the board. With the dual end stop firmware.
After performing some moves all the steppers on the machine are energized and hold position except X1 (closest to the camera). When I move X I can see X2 moves then X1 catches up afterwards it gets to the right point but there’s obviously something wrong.
I know the others are holding position as if I try to turn then I can feel them resist but X1 I can move.
I assume there will be a firmware setting to set this up but I can’t work out what it is, can anyone advise?
Also the PWM_MOTOR_CURRENT setting can anyone advise on what to set it to, to allow the motors to have the full 2A they are capable of the board says it should do 2A. At the moment I have it set to 185 which is 1A I believe but going to 255 produced odd behaviour.
After further investigation on this I’ve found that the stepper motor has an issue, when powered down and turned by hand it does not feel right, it feels notchy, the others feel smooth in comparison.
Taking it apart there’s not obvious mechanical issues, the bearings are fine, I can’t see anything bent or rubbing, but definitely something is off.
It is very rare for a stepper to have a problem. They are very dumb, and robust. More likely are wiring issues, or the pulley grub screws coming loose.
You don’t want to max out the stepper amperage. They will heat up and melt the plastic. Plus, the drivers can overheat. I suggest leaving it at the setting Ryan uses (135?) because you should be fine. If you do fine tune it, put a fan on the controller and watch the motor temp. The motors should stay below about 50C to avoid the plastic moving.
Also, stepper motors have a lot of em stuff going on. If you take a disconnected stepper and short one coil, it will resist itself. Maybe that is the resistance you are feeling?
I thought I had this fixed, but no. BTW The suspect stepper has been replaced, so that is gone.
Currently whatever motor is plugged into the Y2 (E1) socket is not holding torque and is delayed in movement compared to Y1. I’ve swapped Y1 and Y2 motors repeatedly and tried some other motors, the issue stays with the socket.
With all power removed and the motor unplugged the resistance measured across the outer 2 pins on Y2 is 1.7 ohms whereas all the other pairs are 2.3 or 2.4. Therefore I suspect the socket is bad, why? I have no idea.
Moving on looking at the board, if I can map Y to the Z sockets and Z to the Y socket, then I should be back in action again, but I’ll lose the endstop squaring on Y alternatively I could wire the 2 Y motors together, but I’d rather not.
I think that the pin mapping is in pins_RAMBO.h, can anyone give pointer on modifying that? Or is there another way?
You’re measuring the wiring and the motor, or the socket/driver? The resistance measure of an active circuit, like the driver won’t tell you anything useful.
Wiring two motors in series is a good way to do it. We’ve done that for years before we figured out this dual endstop thing. Surprisingly, you won’t lose torque, just torque at high speeds. Do not use the second port on the Z. That is wired in parallel, and it will make you lose half the torque. Series wiring is better. That second Z port is just for small printers, not MPCNCs.
Thanks, yes I was measuring the driver, the fact that all the other were the same and this one was different gave me cause to think something was broken or had changed on it.
For want of any other choice I’ll wire the motors in parallel seem now like I wasted $ getting a full size RAMBO. I’ve emailed tech support at Ultimachine maybe they have some ideas, what I don’t understand is, if I broke it, how? If I can’t work that out then I’ve not learnt anything from the experience and I may well go and do it again.
12:14:06.670 : x_min: open
12:14:06.670 : x2_min: open
12:14:06.670 : y_min: open
12:14:06.670 : y2_min: open
12:14:06.673 : z_min: open
So that looks like its enabled. But that’s reporting on the status of the limit switches? I guess that shows I have the right firmware installed?
My problem looks similar to this one:
They didn’t get to the real bottom of it either.
When it’s powered up and the steppers holding I have 1.15V across the pairs on the other drivers but on E1 0V. So I really think its not doing anything and the motor is just being dragged along.
It os hard to tell from the voltage coming off the driver, because they are constant current drivers, and they are trying to balance two phases of the motor.
Yeah, the M119 was just to see if it was configured for a y2. AFAIK, you can’t configure y2 without configuring the e1 driver, so that’s my quick check.
I would definitely try to work with it in series while talking to ultimaker. They seem to be pretty honest and they have pretty solid boards. I hope they would make it right.
