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Bed Leveling, what makes it back off?  

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scott.b47
(@scott-b47)
Trusted Member
Bed Leveling, what makes it back off?

I've had a recent change in behavior in my MK3 regarding bed leveling. I've been using 7x7, and it always proceeds relatively fast checking each of the 49 positions. About a week ago it started doing this new thing where it occasionally backs the extruder up a bit at a spot. It does this on between a half-dozen and a dozen spots. These spots aren't distributed about the edges (where we might be hitting something) but are pretty well distributed throughout the interior of the sheet.

One time it did an "Enforced Z Calibration" and stopped, though I haven't seen that problem repeat.

The only thing I've changed lately is adding an extruder motor cooling fan, which shouldn't affect movement other than adding a bit of weight to the extruder. I haven't messed with the PINDA probe. I haven't messed with the nozzle. I haven't messed with the live Z.

Can someone explain what it has encountered that leads to this backing off? 

Thanks,

Scott

Posted : 28/07/2019 1:54 am
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(@)
Illustrious Member
RE: Bed Leveling, what makes it back off?

Try tightening the PINDA holder... if it has loosened the PINDA may not be stable.

Posted : 28/07/2019 2:01 am
bobstro
(@bobstro)
Illustrious Member
RE: Bed Leveling, what makes it back off?
Posted by: scott.b47

[...] it occasionally backs the extruder up a bit at a spot. It does this on between a half-dozen and a dozen spots. These spots aren't distributed about the edges (where we might be hitting something) but are pretty well distributed throughout the interior of the sheet.

One time it did an "Enforced Z Calibration" and stopped, though I haven't seen that problem repeat.

I've seen that exact same behavior. It's always been a case where something - usually old filament - is protruding below the nozzle level. Are you able to get good Live-Z calibration results?

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Posted : 28/07/2019 2:25 am
scott.b47
(@scott-b47)
Trusted Member
Topic starter answered:
RE: Bed Leveling, what makes it back off?

Thanks, I'll check pinda tightness.

I've tried it with several different filaments, and I've made sure to wipe the nozzle before letting it do bed leveling. Basically, the same procedure I always follow. My live Z and first layer look fine to me.

Posted : 28/07/2019 3:49 am
cwbullet
(@cwbullet)
Member
RE: Bed Leveling, what makes it back off?
Posted by: Tim

Try tightening the PINDA holder... if it has loosened the PINDA may not be stable.

Thanks.  That is a simple fix that I did not think about.  I will add that to my routine checks.  

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Chuck H
3D Printer Review Blog

Posted : 28/07/2019 11:57 am
JLB
 JLB
(@jlb)
New Member
RE: Bed Leveling, what makes it back off?

Same behavior here.

Since a few weeks, the xtruder goes up a little bit, always at the same position(s).

Pinda is fast, bed leveling is perfect.

Prints are also perfect.

 

Posted : 29/07/2019 2:44 pm
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