1 Topic by RGargus (edited by RGargus 2013-06-16 19:28:41)

  • RGargus
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Topic: Stepper motor missing steps.

My Extruder stepper motor has begun missing steps and "thumping" backwards occassionally, causing my printed parts to be a bit anemic in places.  I swapped out the driver module with the Z module, and it still does it, so I have to presume that either I have quesionalbe wiring between the motor and the board, or that my stepper motor is failing.  I can ohm the wires up to the motor, but I suspect I am seeing an internal motor breakdown.  Any suggestions to help find and cure the issue would be helpful.  I have a motor on order, but would love to get back to printing quickly.

2 Reply by IanJohnson

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Re: Stepper motor missing steps.

There is increased pressure in the hot end, from a clog or a jam in the barrel.  The skipping steps is due to it getting too hard to push the filament through.

3 Reply by pcpoirier (edited by pcpoirier 2013-06-16 18:16:06)

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Re: Stepper motor missing steps.

I had that problem.  Turns out the filament dried out was too hard. I put it in the over for 2 hours at 195 degrees Fahrenheit and my problem was gone.

4 Reply by RGargus

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Re: Stepper motor missing steps.

IanJohnson wrote:

There is increased pressure in the hot end, from a clog or a jam in the barrel.  The skipping steps is due to it getting too hard to push the filament through.

This occurs even when I am trying to back the filament out so I think it is due to a failure.. but not sure.

5 Reply by op7ical

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Re: Stepper motor missing steps.

What about when there is no filament?  Does it still skip?

6 Reply by nlancaster

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Re: Stepper motor missing steps.

I had that problem because the speed in the eeprom settings was not constrained, and it was trying to push too hard.  I limited my extruder speeds in th eeprom and slicer settings to only 15mm/s and problem solved.

7 Reply by RGargus

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Re: Stepper motor missing steps.

Well, as Ian pointed out, it does indeed appear to be some kind of blockage.  I stand corrected on the reverse action, that is all good.  In the process of trying to correct things, I did discover other challenges.  One is that the heater connector is flacky.  On close inspection I see where there was an attempt to solder the wires into the crip connector.  That would explain some of my unexpected shutdowns.  I may also have contributed to my clogging situation, not sure.  The system has worked beatifully since late February so I don't expect it is any EEPROM settings.  In an attempt to get a more accurate reading of head temperature, I drilled a small 1/8 inch hole in the opposite end of the aluminum block from the heating element, and encapsulated the thermistor in heat sink compound within the hole.
I have been unable to seperate the nozzle from the brass tube holding the heater block and the PEEK but I was able to drill with a number 80 drill bit into molten plastic.  Apparently this is too small to remove the obsticle and I fear damaging parts if I continue to force things.
Finding a wire the right size seems to be a challenge.. others have found some.. hint hint??

8 Reply by IanJohnson

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Re: Stepper motor missing steps.

Guitar or violin E strings will fit in the nozzle.  It might be temporary though, you just push around some bit of something that will end up back in the nozzle.  Or you could turn it sideways so it comes out, it's just a big guess.