First print with my first Reprap needs some work... and advice

So I finished my first RepRap, a mini-Kossel design built from a kit. After much calibration (and giving up on the auto-probe as it seems to crash into the bed when retracting), I did the test print for the 30mm cube. It seemed to start off well, but after ten minutes, it said the build was complete (it originally predicted 20) and I noticed my layers were not on top of one another. Instead, my cube is looking like a falling deck of cards. Reference picture attached.

I measured the sides that I could, and they are very, very close to 30mm on all sides. So I just need to figure out why the layers are not centering, and why it quit on me after a few layers. It's only about 1/8 the way up to top, and it didn't even attempt to build the top face. The bottom face did print, but I broke it when removing it from the bed.

I'm thinking as for the stack up, maybe my X and Y are not centered and it is gaining mm in each direction when it homes. Still seems like it would print on top of one another, though... just offset from center to begin with. As for the Z level, I have no idea. The layers look good... for the most part. The extruder still needs a bit of tweaking, maybe it's off by a few fractions of a mm from doing the 100mm extrude command test.

Any advice would be much appreciated.

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"Pfft. Third dimension... what dimension do we even live in?" - Charlie Kelly

Check your belt pulleys, one or more is probably loose, also make sure your bed is held down tight.

It looks like you are missing steps. You may need to tweak the current on your stepper drivers up a bit

Exactly right, my friend. I noticed on a second printing that one belt was gaining slack in the negative direction. I must have slipped during one of print failures.

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"Pfft. Third dimension... what dimension do we even live in?" - Charlie Kelly

The first thing I would do is get a file or dremel and carve a flat surface on each stepper shaft. If your using abs goop take some and dip the set screws in or use thread locker to set them in tight. Secondly you need to tune your stepper drivers. Also you may need to check for binding in movement then check your speeds. Tune them to 30mm or so per second and work your way up. Also check acceleration settings. You may need to lower it a bit in firmware. Good luck.

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Modicum V1 sold on e-bay user jaguarking11

Fixed the belt, but still having Z level problems. I think I have a clue. When moving, the machine is whisper quiet, but it shudders a lot when printing. I think it may be laying down too much material and the head is rubbing against it, putting it out of square. Perhaps it's calibration for the extruder? Also it's still not getting even close to 30mm high, which leads me to believe the Z step is for whatever reason broken.

Edited 1 time(s). Last edit at 12/18/2014 09:07AM by Rett Mikhal.

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"Pfft. Third dimension... what dimension do we even live in?" - Charlie Kelly

If your head is rubbing against the printed part, its most likely the steps per mm are set wrong. Are you using a 20T pulley or a 30T one or a 16T? etc etc... It is also possible you may have an out of round pulley.... I had 1 in my 10 pack. But I tend to inspect my parts before I install.

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Modicum V1 sold on e-bay user jaguarking11

They are GT2-20T timing pulleys. I'll check the guide on calibrating them.

[docs.google.com]

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"Pfft. Third dimension... what dimension do we even live in?" - Charlie Kelly

Hmm... I checked the calibration and they all seem fine. Everything is set to 80 steps/mm.

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"Pfft. Third dimension... what dimension do we even live in?" - Charlie Kelly

I'm running out of things to check. I tried a different slicer and had the same result. I made my own calibration cube file with the same result. I checked the steps/mm settings several times and everything is fine. I checked the firmware measurements and did a bed level check, the head doesn't lose a single fraction of a mm from dead center to all points along the bed.

The first level is also always perfect.... could it be some combination of incorrect measurements in the firmware that is adding up to an incorrect delta calculation? Still doesn't explain why the Z=0 level test is perfect, though.

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"Pfft. Third dimension... what dimension do we even live in?" - Charlie Kelly

Did you increase the current as suggested by AndyCart?
Did you check your extruder settings, both for size of filament and steps to extrude the right length of plastic?

From your attachments it looks like missed steps.
You could also try a different power supply, it could have issues causing it to fluctuate which could result in the missed steps.

I found the problem. I had incorrectly set the Z_min to a height other than 0 (+28mm) to avoid crashing the head during testing, but neglected to put it back. Once I did that (AND ALSO reset the Z_home with the adjusted value), it prints fine. The problem was that the +28 was making it so it could not do Z0, or Z anything below 28, and thus it was only raising the Z level because it was rubbing against the laid down plastic. Now the thing prints smooth as glass. Big thanks to Think3dPrint3d for their tech support (on Christmas Eve, no less!!!)

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"Pfft. Third dimension... what dimension do we even live in?" - Charlie Kelly

Glad you found the problem and I was able to help, cheers!

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