Hello everyone. I just finished uploading the firmware (MPCNC813_GLCD_T8) into the ramps, I have 8825 drivers, the x and y axis work fine, although the stepers vibrate a lot. but the Z axis when I try to move it through the display, it only vibrates, it does not move. I changed the drivers places, but it does not matter, it’s always the z axis that does not go. I am connecting the motors directly with their cable, I still do not put them in series.
that could be happening?
Have you adjusted the voltage on the drivers?
Is it just the perspective, or are those motors enormous? I don’t think it should matter, but they look huge.
In the pic, you’ve got one motor directly connected to the Z and even in that configuration, without being connected to the machine, it doesn’t move?
You said you tried that driver in another port, have you tried that motor in X or Y?
If you can run that motor in another port, and you can run that driver in another port, then it’s got to be the ramps, or the arduino or the arduino software. Or I guess it could be how you are trying to move the Z. It should move in either direction though. Are you using the LCD to move it?
Do you have all three jumpers on the step select pins under the drivers? And as Jeff asked the driver setting is just as important.
Yes, three jumpers each driver. I doesn’t set the voltage yet, but if I put the Z driver, on X or Y, the steppers works. Any of the three drivers fail on the Z socket. So, the stepper works, the drivers works. There is any other thing to try or the problem is on the ramps?.
If the problem is on the ramps, can I change the pins_RAMPS.h file to use E01 as Z on your firmware without any other change? it will work?.
thanks
You can try that.
You have to set these, them come set maxed out and that is very bad. Typically they thermal throttle after a few seconds like this.
I missed the part about it vibrating. If it’s trying to move, then it’s probably not the software.
Try these things:
I think what’s happening is that you’re on the edge of skipping steps on all the motors, probably because you haven’t adjusted the drivers. The Z axis is trying to move 800 steps/mm compared to the 100 steps/mm of X and Y. So the same movement in X or Y is causing 8x speedup in the Z direction. That speedup means it’s trying a lot harder on Z than on X or Y.
I’ve reviewed and old discussion you had with JeffE3B and C in 2016:
‘Current limit Stepper drivers drv8825’
From what I’ve read elsewhere, smaller microstepper intervals (eg 1/32) seem to give smoother and quieter operation and likely a measure more of precision to the CNC movement.
However, it looks like the trade off with Smaller microstepping intervals is more current draw compared to Full Step rates so more heat generated by both the stepper driver and the stepper motors. That explains why those little heat sinks on the Arduino Shield get too hot to touch and the test motors I’m running get Much hotter than when I’m running from a Rambo board. It also explains why the common default is typically 1/8 step I suppose, cooler running.
So, in answer of my question posed above, use the smallest microstep you can get away with considering current draw, torque requirements for milling, precision expectations, equipment heat tolerances, and the glass point of your MPCNC mounts.
Sigh… Trade offs again.
The step rate should have no effect on current draw. What you are reading is from when we used parallel. In series we now have more than twice the current, there are no trade offs now. 0.75 on a DRV driver is more than enough for the steppers I sell. You can take a drv up to about 1.1V with a fan but at that point you will probably destroy your stepper.
Be careful with old info.
