Extruder Motor Issue!

christiangentry · 2016-09-29T14:26:17.000Z

There’s rarely an issue with the stepper motors. I’ve had feeding trouble, also, and it’s always been a mechanical issue such as the tension spring had too much or too little tension.

One other factor you may not be thinking about is thermal issues. If the ambient temperature in your printing area is too cold, you will have trouble with feeding.

Can you respond with specific details about what you’re seeing? For instance, when you preheat the hotend, then extrude do you see the hob rotate and chew up the filament? Does the hob NOT move? I think if you can paint a clearer picture for us we could help more.

ABigBirch · 2016-09-29T14:37:30.000Z

The stepper motor does not run smoothly, it will rotate on its own when it is not installed, but it has a very jerky motion. It’s a new motor, and the old motor does the same thing when connected to that cable.

ABigBirch · 2016-09-29T14:43:51.000Z

The filament does not get chewed up and the and there hasn’t been anything wrong with the temperatures. (I installed my hot end on another printer, and it worked fine) The motor doesn’t seem to have enough strength to push the filament through, it is unable to strip the plastic off the filament. It twitches back and forth when it hits any resistance. The hot end is also completely clear of all plastic debris.

christiangentry · 2016-09-29T14:44:17.000Z

If the same behavior is occurring with different motors, then the issue is likely not the motors. It could be a physical issue with your controller board such as power delivery or firmware. Also, wiring is always a possibility. “Jerky” sounds like a bad connection, so that may be a good place to start.

ABigBirch · 2016-09-29T14:47:52.000Z

It is a modified Prusa i3 printer, the whole extruder assembly is completely clean and free of debris. The two wheels are under the correct tension. The plastic does have the small dimples. When the filament does not extrude, it is not being stripped either, the motor simply twitches back and forth, like it’s too weak to do the job.

ABigBirch · 2016-09-29T14:49:43.000Z

Thanks for the reply, I’ve ordered new wiring. I’m not sure it’s the control board, because every other motor works perfectly, and it’s a new board that I had replaced rather recently.

ABigBirch · 2016-09-29T14:51:52.000Z

When the motor is not installed, I can easily push the filament through. Even when the motor is installed, if I help push the filament, the motor will extrude it, on its own it is unable to.

ABigBirch · 2016-09-29T14:55:16.000Z

I now know it’s not the hot end, I’ve installed it on another printer and it worked printed fine. I checked the vref, and it seems to be sitting at 0.2. How much would I have to turn the trim pot on the stepper driver to increase this? Or is that just for increasing the current?

ABigBirch · 2016-09-29T14:56:41.000Z

My vref is at 0.2, what would be the best way to increase this?

ProtoPlastik · 2016-09-29T15:44:43.000Z

Is it a RAMPS board? If so, check to make sure you have all the jumpers in place. Got tripped up by that one more than once. Try swapping out drivers.

christiangentry · 2016-09-29T15:56:14.000Z

The following possible causes come to mind

a) physical connectivity: polarity reversed?

b) firmware needs reflashed

c) hotend temp lying! Thermistor issue? (it it doesn’t extrude, maybe its not hot enough)

Please use the “divide and conquer” technique for troubleshooting

Isolate the faulty / problematic variable. Do this by testing the integrity of each component SEPARATELY. This will include running the stepper motor by itself from a static power source, or plug it into a different port then manually control it to determine if its faulty or healthy. Also, you’ll need to test the port on the controller board with a different motor. When testing it don’t have the motor installed on your extruder. Divide and conquer.

“Twitching” instinctively seems like a physical connectivity issue. A shorting wire that is exposed or something else that is affecting the continuity of the circuit.

EDIT: not enough power to extrude the filament could be just that: a power issue. You need to use a multimeter to check the appropriate power is being delivered all the way from the PSU to the stepper motor’s port.

Ronca · 2016-09-29T16:01:27.000Z

Can you make a picture of your electronic board (ramp)? So we can check together where the pololus are and I can follw you better in adjusting the value.

We also do need the type of your extruder stepper motor, in order to know the electric features

Feel free to send the picture(s) to d.roncadori@gmail.com

besser · 2016-09-29T16:56:11.000Z

Try upping the current it is receiving.

Perry_1 · 2016-09-29T22:36:18.000Z

It is NOT the stepper. They rarely fail, and your testing and subsequent posts imply it is not the stepper.

It is likely the wiring has gone bad. This is common for the stepper wires, which break inside from repeated same movement over and over.

Test a different wire, such as using the one from your y-axis. I’ll bet a dollar you will see the wire is bad.

PS If you have a ptfe liner, replace it now and then, it can cause these issues, but my money is still on the stepper wire.

ProtoPlastik · 2016-09-30T01:25:03.000Z

A whole dollar?

when steppers fail, it’s usually due to overheating which can warp the core where the windings are wrapped. This will cause the rotor to “hunt” for its index. In my case, the stepper would oscillate back and forth.

ABigBirch · 2016-09-30T17:56:08.000Z

Update (Problem has been located):

I switched the cables around, and there was no change.
I switched the stepper drivers for the extruder and the z-axis, and the filament started extruding more smoothly than ever before!
I had switched the drivers before, but with a different motor for the extruder. With the original motor for the printer, and the z-axis driver, it worked.

Thank you to everyone who helped, hopefully when the new driver gets here, there will be no more issues!

ABigBirch · 2016-09-30T17:59:22.000Z

Thanks for the help, but I have actually found where the problem was. It was the stepper driver for the extruder.

ABigBirch · 2016-09-30T18:02:43.000Z

It actually was the drivers! I switched them out the first time, using the newer motor I had, and nothing different happened. When I switched to the motor that came with the printer, and then switched the drivers, it started extruding plastic perfectly. Thanks for the help.

wirlybird · 2016-09-30T18:12:57.000Z

Good to hear. Thought you had checked the drivers and they were ok but good it is solved.

kissfan4 · 2016-10-01T19:47:15.000Z

I experienced something very similar, mine was harder to track down as it would only occur occasionally during prints. My printer would start out fine, then some time during the print my extruder would start jerking like you described. I thought it was temperature so I added active cooling, which did not help, I finally tracked it down to the plug on the end on the cable where it plugs into the stepper. The way mine is set up the flexing over time wore it out, and instead of trying to order a new one from china, and possibly having the issue again, I opened up the stepper and hard wired the cable, then built in a little strain relief using the case of the stepper itself. That was probably close to a year ago, and have not had an issue since. But in diagnosing this you need to be careful with the steppers being unplugged while being energized.