Print shifted

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LonV
Posts: 220
Joined: Thu Nov 15, 2012 11:53 pm
Location: Phoenix, Arizona, USA

Print shifted

Post by LonV » Thu Dec 12, 2013 5:27 am

So, I was printing this object and about 15% of the way through it started printing about 2mm offset front to back. I remember hearing about this happening to people, and Drew suggested that maybe rotating the object while slicing causes that problem. Sure enough, I _had_ done that.

So, I resliced, making sure not to mess within anything (I was actually out of the room). This time, it printed about 50% (12 hours!) and started printing offset (front to back) about an 30mm.

I'm slicing again at .2, instead of .15 (it's a 24 hour print) and trying again, but curious if anyone has ever gotten to the bottom of this? I've had my printer for over a year and it's never happened to me before.

-Lon

mr6k
Posts: 327
Joined: Tue Feb 14, 2012 11:47 am

Re: Print shifted

Post by mr6k » Thu Dec 12, 2013 10:18 am

not sure if this will help but i recently had a similar problem with a random offset occuring laterally. the first couple of times i was not at the printer when it happened and on one of those times i came back to a stopped printer reporting a positioning error.
i then ran another print and heard a stepper motor slip, a momentary buzz. at that instant the offset occured,

on inspection i found that dust build up on the metal frame below the lateral linear bearing, behind where the extruder head is mounted, was so much that it was jamming the bearing. this could be felt, turn off the printer and move the head by hand, any tight spots can be felt. so i cleaned the area and now all is ok. I guess this can happen in either pliane.

cheers

peter

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DrewPetitclerc
Posts: 581
Joined: Sat Feb 12, 2011 7:39 am
Location: Silicon Valley California
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Re: Print shifted

Post by DrewPetitclerc » Thu Dec 12, 2013 5:00 pm

Also, if your print is experiencing any lift the nozzle can run into the raised part and cause a belt slip in either the X or Y and from then on the printer continues with the incorrect position.
Remember this is not a position encoder it is a step positioning and even poking a finger in and applying any resistance to the build plate or extruder can cause the belt to jump the geared pulleys.
Regards
Drew
Drew Petitclerc
Petitclerc Designs
Owner/Senior Principal Designer, prototype, tooling and test equipment design and 3D printing
http://flash-graphics.deviantart.com/
http://www.thingiverse.com/DrewPetitclerc

pleppik
Posts: 336
Joined: Sun Dec 11, 2011 2:14 pm

Re: Print shifted

Post by pleppik » Fri Dec 13, 2013 12:01 am

I've had a similar problem on the X axis, with jumps of up to 5mm. It's been maddening to troubleshoot--I've checked every mechanical component, cleaned the bearings, replaced the stepper motor. But it's not reproduceable enough to know for sure if a change has fixed the problem.

It hasn't happened to me for about three weeks, since I replaced the hot end for unrelated reasons. Could be coincidence….I don't see how replacing the hot end would fix X-axis slippage.

Scott_Morgan101
Posts: 4
Joined: Sun Aug 11, 2013 2:50 pm

Re: Print shifted

Post by Scott_Morgan101 » Mon Dec 16, 2013 4:23 pm

Can I ask if you're suing the little bulldog clips supplied?

In my case of shifting parts I actually saw the perfboard move by random chance. I wasn't using he clips because I wrongly assumed the springs on the bed would be strong enough - they're not.

Not had another occurrence since I started using them.

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