Ribbed prints

I've just build my first reprap (prusa I3), and finally got an acceptable result.
However my print seems kind of ribbed.

I suppose it's because the extruder is stuttering. (see youtube movie: [www.youtube.com])
The stepper on the extruder seems to tremble a lot more then the other steppers, even when working unloaded (without extruder mounted). I've tried the extruder on pins from X axis, where it works properly (no trembling). Therefor i think it has to do something with the configuration.

Any idea how to solve this?

My build is: sintron frame (http://www.benl.ebay.be/itm/161561879405?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)
sintron extruder (http://www.benl.ebay.be/itm/151552176556?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT),
RAMPS 1.4,
astrosyn steppers (17pm-k502-g3s1),
A4988 stepper drivers,
Marlin firmware (adjusted by Sintron)

Maybe you need to adjust the driver current for the extruder? Did you try swapping the driver from X to the extruder?

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Newbie with Folgertech 2020 i3.

Yes, I tried the x driver, same problem. I've also tried to adjust the driver Current, but I'm afraid to turn too much and damage the driver or motor. Also, if I turn the potentiometer clockwise or anti clockwise 180 degrees, the motor stops turning at all!

Check the jumpers under the extruder driver, they might have bad contact.
-Olaf

Quote
o_lampe
Check the jumpers under the extruder driver, they might have bad contact.
-Olaf

How can i verify this for sure? Is this case a motor missing steps?

Jumpers with bad or intermittent contacts would cause the stepper to run much faster and extrude twice the length. ( hence the ribs? )
The overkill amount of filament stresses the stepper too much and can cause skipping steps.

If you have a ohmmeter or multimeter, you can beep the jumperpins for continuity.
Anyways, it is mandatory to calibrate the e- steps.
-Olaf

Edited 1 time(s). Last edit at 10/25/2015 02:38PM by o_lampe.

My guess is that you are over extruding. That may be what is causing the stepper to skip. Try changing your "Steps Per MM" It should be in the area of 150.

I followed a calibrate procedure, and had to calculate the steps per unit, what gave me 6.4 steps per unit, what seems incredibly low to me. However, the result is VERY much better.
I just can't comprehend why it is such a low value... According to the preconfigured firmware this had to be 94, but in that case my extruder feeds 12 cm when i asked 10mm (manually).

Another thing that seems strange to me, is the setting to manually extrude in pronterface has to be set on 1mm/min to have an acceptable feed.
Could there be some misunderstanding of unit? mm in stead of cm...

I've attached a copy of my configuration.h, perhaps if someone could have a look, it would be appreciated!!

It sounds like something is wrong with your microstepping. If you take the number they gave you (94) and devide it by 16 (a very common microstepping multiplier), you get 5.875. This is really close to the value you found to work. You should make sure that you have the little tiny black jumpers installed underneath your driver board. You might have to do some googling to figure out which jumpers you should be using for your set up.

Using the number you found will work, and if it is working well I wouldn't even bother trying to fix the microstepping. But if you start to have more problems, I would try to get this issue worked out, after all your extruder has become 16x less precise.

Quote
AudaciousTuddle
It sounds like something is wrong with your microstepping. If you take the number they gave you (94) and devide it by 16 (a very common microstepping multiplier), you get 5.875. This is really close to the value you found to work. You should make sure that you have the little tiny black jumpers installed underneath your driver board. You might have to do some googling to figure out which jumpers you should be using for your set up.

Using the number you found will work, and if it is working well I wouldn't even bother trying to fix the microstepping. But if you start to have more problems, I would try to get this issue worked out, after all your extruder has become 16x less precise.

First time I hear about these jumpers. Never paid attention to this, I don't even know if there are jumpers... This probably will be the problem!
Would you mind giving me a little explanation what's their purpose?

Just did some googling, and now everything becomes clear. You're a lifesaver man!!! I've been busy calibrating the last 3 days, without good results!!
Seems like the jumpers weren't included in my electronics pack I've purchased on Aliexpress.
First work tommorow is go get some jumpers!!
Many thanks!!

I learned from screwing up myself. I also got a kit from Aliexpress. I never put them in because the terrible instructions never told me to. Took me a week of googling to find the answer.

Quote
o_lampe
Check the jumpers under the extruder driver, they might have bad contact.
-Olaf

I asked you about the jumpers a while ago...
-Olaf

Yeah Olaf, but I didn't really knew where you were talking about. My electronics came without the jumpers...
Anyway, thx for the help!

Jumpers are installed, and it works like a charm!! Nerdgasm!!