Displaced Prints and Projections

Hello,

I am getting displaced prints just as shown in the photo. I also notice some small projections on the surface of the prints, making the surface rough. From the preview in Pronterface, the print is not distorted or displaced. What seems to be the problem?

I'm using: Slic3r, Printrboard, PCB Heatbed MK1, J-Head Mk IV-B Hot End for 3mm filament.

Thanks,
Wayne

Most likely either your stepper motors have suddenly lost steps or your part/bed has slipped.

Loosing steps can happen if the current to the motors is too low so you could turn the pot up a bit. I generally run my motors warm to the touch but not hot since this shortens their life+would melt my Pla mounts.

You will loose steps if a stepper driver overheats, so I recommend a fan on your electronics.

Is the glass bed unable to move/could your part have become unstuck (unlikely that you wouldn't notice)

Motors can loose steps if a part curls upwards in the way of the hotend, is there any sign of this?

You definitely lost some steps on your x axis up at the end of your print. Could be curling pla getting your hotend stuck as was mentioned. (I'm still dealing with curling on some prints myself). If it wasn't curling then maybe you have your x driver set too low.

As far as the pimples, some one with more experience needs to explain that. I dunno if it's normal, too much extrusion, temp related, retraction related, or other...

Thank you all for the replies. So I should increase the current until the motors are warm to touch when running? I don't think there were curling of the printed parts, or the hotend stuck by the filament.

Check all your pots Vref values. See where you are. you could just turn up your x/y drivers a little, or turn them all up a little if you want. But yes you never want your motors any hotter than "warm".

Edit: don't overlook the obvious like slipping motor pullies.

Edited 1 time(s). Last edit at 01/14/2013 03:07PM by xclusive585.

Looks like pully slip to me.

Edited 1 time(s). Last edit at 01/14/2013 03:48PM by Greg Frost.

I have increased the current, tightened the belt and the pulley, and printed again. The displacement is at the same place as before. Is it due to a problem of the gcode?

the other thing you can do is reduce the jerk setting in the firmware. perhaps there is a resonance in the gcode at that point that allows it to build up enough momentum to cause a motor skip.

Looking closer, I think it does look like skipped steps rather than pulley slip.

Greg Frost Wrote:
-------------------------------------------------------
> the other thing you can do is reduce the jerk
> setting in the firmware. perhaps there is a
> resonance in the gcode at that point that allows
> it to build up enough momentum to cause a motor
> skip.
>
> Looking closer, I think it does look like skipped
> steps rather than pulley slip.


+1 to jerk and acceleration. I was still losing some steps randomly when my Prusa started shaking during prints.

Reducing Jerk and Accel by 25% was a simple fix that worked. (Of course you also slow down your machine by doing this)