Layer shift

[MSURunner]

Alright, so I've the Rostock churning out some nice looking vases, however, when I'm trying to do more complex parts, I'm getting this weird layer shift. I initially thought it was a product of too little belt tension and the teeth were slipping. However, I've tightened the sheeeeet out of them now and it almost seems to have gotten worse... Is it possible to have too much belt tension on the things? What's the "appropriate" amount of tension? Or is this not related to tension at all? I haven't adjusted any of the acceleration or jerk setting from the .83 firmware.

[img]http://i.imgur.com/y2islE3.jpg[/img]
[img]http://i.imgur.com/MC5wkVw.jpg[/img]
[img]http://i.imgur.com/K1C6ail.jpg[/img]

As you can see, it is happening at different times throughout the print, based off the same file, so my inclination would be something mechanical... Thoughts?

Also, as an somewhat unrelated note, but problematic nonetheless, using an OPS value other than 1 stalls out the print. Thoughts on that?

[cope413]

too little or too much tension can cause shifts like that...

If it's happening at the same height every time, regardless of print, then you have a machine calibration error (tower height, endstop, tower position, tower level, etc).

If it's happening randomly, then you could have a pulley that's slipping, you could have a cheapskate that's too tight or too loose, or you could have a flat spot on a bearing cover.

You could also be printing too fast.

[dpmacri]

I had a similar layer shifting problem recently (mine seemed to be a bit worse than yours). When it happened, I had *unfortunately* changed 3 things all at once: I had installed an E3D hot-end, changed filament, and upgraded the firmware from 0.80 to 0.83. I didn't think the filament would cause it, and once I made sure the hot-end was mounted well, I figured it must have been due to the firmware change. Doing a diff between the two version, I found that the latest update from SeeMeCnc has the current to the motors set at 175. Previously they were at 195. Changing that for me fixed the layer shift problem. The line you're looking for in Configuration.h lookes like this:

#define MOTOR_CURRENT {175,175,175,225,0}

Change it to:

#define MOTOR_CURRENT {195,195,195,225,0}

Hope that helps!

BTW, I would *assume* that tightening the belts might make the motors need to work a little harder. So if the current was weak to begin with, tightening might mean you get more missed steps on the motors. Just a theory, of course

[MSURunner]

I'll go with that theory...

I'll bump up my current and bump down the tension a "skosh" and report back.

[Lochemage]

Also double check that your U-Joints are still turning smoothly and easily. I've had them get 'stuck' like they were welded together before and that caused quite a bit of problems with my prints.

[MSURunner]

Tricklaser arms so that wasn't the issue. Bumped up the current to 205 and lowered tension a bit. Everything is reeeeeeeal good now

[626Pilot]

Try changing DELTA_DIAGONAL_ROD to 271.0 and see if it still fails at the same height.

I have Trick Laser arms and I had to make that change in order to get anything tall to print.