1 Topic by centipede (edited by centipede 2013-03-28 16:25:22)

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Topic: X and Y shifting on SD3 - Belt? Voltages?

DESCRIPTION:
Hello, I am on my second day with a running SD3, and I am experiencing dramatic shifts in the Y layer. After attempting to adjust the voltages, the latest print also has X shift.
The problem arises after approximately 10 layers of printing. A test print of a 0.5mm-walled rectangular tower came out fine.
The problem is identical with both white and black filament.

PRELUDE:
Upon receiving the printer, I had to glue the X-carriage part that the rod runs through, since it was ripped apart at the layers. Seems to work fine.

ATTEMPTED SOLUTIONS:
Followed the video regarding belt adjustment: (Can't link to the wiki at solidoodles homepage)
I have tried to calibrate the Y-voltage as per: (Can't link to the troubleshooting page at solidoodles homepage)

As I explained to Solidoodle's support team:

They are off:
X: .458 (should be .443)
Y: .543 (should be .520)
Z: .517 (should .500)
E: .197 (should be .192)

The closest I could come on the Y voltage was .512 which is still closer to .520 than the original 0.543 (that pot is astonishingly sensitive).
Oddly enough, the next print had a few correct layers more, but then started to shift in X also. It still shifts in the same direction: Y closer to home, and now also X closer to home.

Addition: Sometimes it seem to shift back again a little bit too.

Solidoodle support tells me that in very many cases the problem relates to improper belt adjustment. I am experimenting with figuring out the tightness of the belt. If anybody have good hints or links to tutorials besides those mentioned before, I would be happy to hear them.

Rene Jensen

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2 Reply by centipede

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Re: X and Y shifting on SD3 - Belt? Voltages?

... Posting to increase my post count ...

3 Reply by centipede

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Re: X and Y shifting on SD3 - Belt? Voltages?

... Again ...

4 Reply by centipede (edited by centipede 2013-03-27 19:51:48)

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Re: X and Y shifting on SD3 - Belt? Voltages?

ADDITION:
You can hear how it sounds in this short video. At approximately 0.03 there is an audible halt of the motor while moving in the Y direction.
http://www.youtube.com/watch?v=AGRqRGJr … e=youtu.be

5 Reply by cmetzel

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Re: X and Y shifting on SD3 - Belt? Voltages?

Did you tighten all the set screws on the pulleys?  One of mine was loose and I had a similar issue.

6 Reply by centipede

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Re: X and Y shifting on SD3 - Belt? Voltages?

I wish I had better sense of how tight they should be. Initially I loosened them further because the carriage felt heavy to move.

I wish I understood why nothing bad happens for the first 5-10 layers.

7 Reply by nlancaster

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Re: X and Y shifting on SD3 - Belt? Voltages?

Centipede, I am the exact oposide for the first 10-20 layers it drifts int he x-axis directionn a tiny amount.  Solidoodle tells me to run the calibrations at a link but all the calibrations talk about is the y calibration.

8 Reply by nlancaster (edited by nlancaster 2013-03-28 01:00:08)

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Re: X and Y shifting on SD3 - Belt? Voltages?

Centipede, I am having the exact oposite for the first 10-20 layers it drifts int he x-axis direction a tiny amount then goes away.  Solidoodle tells me to run the calibrations at a link but all the calibrations talk about is the y calibration.

http://www.pdxmc.com/uploads/SD3/20130326_214011.jpg

9 Reply by paeltz

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Re: X and Y shifting on SD3 - Belt? Voltages?

If you turn off the motors (click emergency shutoff in repetier) does your carriage move freely in both the X & Y direction?  I had to re-adjust my Y axis very shortly after I got mine.

10 Reply by centipede (edited by centipede 2013-03-28 14:35:19)

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Re: X and Y shifting on SD3 - Belt? Voltages?

SOLVED

First, forget my observation that the print was still off after adjusting the Y voltage. False negative. May heaven strike me with thunder for being a fool: I managed to overlook the black filament (in a dark room) which had entangled itself.
I can attest that in all my previous attempts with large skipping, the filament was running freely.

Summary of my experience:

SYMPTOM

Large slips in position during and inbetween layers. Not small inaccuracies like in nlancaster's case (I get those too), but slips in the order of several mm or cm. Prints are useless.

In my case the slipping occurred typically after 5-10 succesful layers, mostly towards Y-home and always in the Y-direction.

SOLUTION

Did not work: Adjusting belt tension and such: http://wiki.solidoodle.com/belt-adjustment.
Did work: Instructions for Adjusting the Stepper Motor Chips: http://www.solidoodle.com/how-to-2/troubleshooting/

I believe that the discrepancy of the Y stepper was beyond a tolerable level.
Here are the previous voltage discrepancies:

X: .458 (should be .443 - off by .015)
Y: .543 (should be .520 - off by .230)
Z: .517 (should be .500 - off by .170)
E: .197 (should be .192 - off by .005)

After adjusting the Y voltage, I ended at .512, i.e. off by 0.008.

I have no idea what the tolerances are. I'd rather undervoltage than overvoltage, but that's just a stomach feeling, not scientific sanity.

11 Reply by centipede

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Re: X and Y shifting on SD3 - Belt? Voltages?

paeltz wrote:

If you turn off the motors (click emergency shutoff in repetier) does your carriage move freely in both the X & Y direction?  I had to re-adjust my Y axis very shortly after I got mine.

Depends on what you mean by freely. I still feel that there is heavy resistance, and what's more, it doesn't feel uniform across the Y axis. It is hard to say though, since pulling asymmetrically on the left and right can put the carriage in a mechanical deadlock.

I am actually quite surprised how much force is needed from the stepper to turn the rearmost rod. Tried to do it by hand.

But as mentioned above: The voltage did the trick.

There are still minor inaccuracies, but I think they more relate to belt tension, lack of grease etc.

12 Reply by ronsii

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Re: X and Y shifting on SD3 - Belt? Voltages?

Try sliding the back rod(y rod) sideways(left or right) a millimeter or two and see if it makes difference in the turning resistance, all it takes is a small burr on one end of the rod and it won't turn easily in the bronze bushing, I have seen this in lots of different machinery and I think another member here found this to be the problem with his SD2