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layer random shift

Posted by dnspower 
layer random shift
August 06, 2012 06:14AM
i print a mouse many times,every time the layer random shift,i use ramp 1.2 and sprinter fireware,feed speed 60mm.
but i print the small part is ok,i don't know what happen in my printer?
can you help me?
open | download - 20120806185.JPG (574.7 KB)
Re: layer random shift
August 06, 2012 07:06AM
I get this from time to time. First thing to do is check that your belts are running true and not running off of the bearing guides. This could be your stepper drivers shutting down briefly due to getting too hot. Check the obvious issues with friction. With the power turned off, you should be able to move the bed (Y axis) and head ( X axis) easily. If there is a lot o drag, check that the smooth rails are parallel and that the belts are not running up against the metal each side of your guides. If it is doing this, this puts quite a load on the steppers which can cause the drivers to overheat an protect them selves. If your belts are not running true, checked that your frame is accurately bolted through. Errors oven a fraction of a millimetre really show them selves up here. Check that you printer is sitting on a good hard flat surface.

Add a fan to your controller board to keep the controllers cool.

What causes it for me is the print head nozzle catching on buildups of plastic but, very often, it knocks the thing off of the bed. If this is the case, check your extruder calibration to make sure you're not pushing out too much plastic. I had problems with 0.8.3 screwing up retraction and bobbing plastic.

Using ABSPrusa Mendel Zaphod with Pronterface and slic3r 1.3.0. Printing well with 3mm PLA and ABS through 2 x J Head Mk IV b and Wade Geared Exruders. Controlled using RAMPS1.4 board running Marlin_v1.1.9
Re: layer random shift
August 07, 2012 04:52AM
i have checked every one but layer alway random shift.can i do somrthing in repsnapper or fireware?
Re: layer random shift
August 07, 2012 05:23AM
As MBS said, you should start by verifying your calibration (especially Z and extruder) are correct, because if you do not lift enough between layers OR you send too much plastic, you could experience this.

It also can happen only on certain parts, when the infill is going through a very tiny "tunnel" leading the head to do a lot of fast direction changes in a little space => if the motor is near its limits (for the current it is fed), it skip steps during those shaky passages.

From your picture, it's probably not what is happening here, as there is no thin in-filled channels in your mouse. I mention it because the possible fixes could also help : I'd try to
1) give more current to the motor (but avoid overheating the driver).
2) lower the firmware acceleration settings a bit.
3) or as last resort try to lower print speed - although 60mm/s should be possible - what machine is it ?

Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.
Re: layer random shift
August 17, 2012 01:19AM
i have found the reason about shift,i think the hotend is too cold,when meet some small abs on the layer,it will random shift,i make hotend up to more power,shift disappear
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