wlg
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P.I.N.D.A. probe misaligned

Sun Jul 03, 2016 1:16 pm

Hi there!

I upgraded my original prusa i3 to the mk2 version this week-end. But I have a little issue with the PINDA probe.

From the various advices/tutorials/etc from Josef, the probe should be aligned like this :
Image

However, mine is more like in the third case, a little off (see attachments below).
This is particularly obvious when doing the 9points calibration as the last one is totally missed.

I don't know what can cause this issue, if someone has an idea I would greatly appreciate it :).

Thank you in advance for any help!

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christophe.p
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Re: P.I.N.D.A. probe misaligned

Sun Jul 03, 2016 3:42 pm

Hi Wig,

This is a very common issue that can be fixed by fine-tuning the build of the printer.

Actually there are several factors and adjustment to consider to fix this, everybody have to make it once (excepted the very lucky one ^^).
To fix that, you should consider the Pinda position on multiple position on the heatbed, not only one. In fact, I consider that fixing the first 3 front positions should be enough to fix the 6 remaining positions.

Here is below 3 different issues that you can have:

Side shift:
Twisted.png
Twisted.png (16.22 KiB) Viewed 2503 times
This one should not be seen often, due to the build design. But the End-stop can have a tiny side translation needed. For that you need to unscrew the screws holding the endstop, push the endstop on the proper position, and while holding it, screw it again.

Front shift:
Front.png
Front.png (16.34 KiB) Viewed 2503 times
This happen when the Z-frame is not positionned at the proper distance from the back of the Y-frame. To fix it, just unscrew the M12 bolts holding it, move the Z-frame back (or front, depending of the position of the pinda relative to the heatbed probe circles, and tighten it back. Be sure to maintain the Z-frame flat while doing that, so I recommend you to remove the 4 pads under each corners and to place a stack of papers or business cards below right and left side of the Z-frame during this operation.

Twist shift
Side.png
Side.png (15.81 KiB) Viewed 2503 times
Probably the most common issue, and this is why considering a single pinda position is not helpful. This happened when each side of the Z-frame are not at the same distance from the back of the Y-frame, or if your Y-frame is not perfectly square.Like the front shift, just unscrew the M12 bolts holding it, move the Z-frame back (or front, depending of the position of the pinda relative to the heatbed probe circles, and tighten it back. Here again, be sure to maintain the Z-frame flat while doing that, so I recommend you to remove the 4 pads under each corners and to place a stack of papers or business cards below right and left side of the Z-frame during this operation.

Most of the time, you will have a combinasion of front shift and twist shift at the same time. Take your time to fix the alignments based on these explaination, consider this time as an investment, you'll be very happy after :)
Last edited by christophe.p on Sun Jul 03, 2016 3:56 pm, edited 1 time in total.
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prusayo
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Re: P.I.N.D.A. probe misaligned

Sun Jul 03, 2016 3:52 pm

Great explanations. The side and twisted pictures don't match the text though. Also, I tried pushing end stop sensor as far as possible but it is still misaligned slightly by the way.

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Re: P.I.N.D.A. probe misaligned

Sun Jul 03, 2016 3:59 pm

Thanks for pointing it Prusayo, I fixed the mess ;)

Yes there is not a lot of margin for the endstop, and most likely you can easily make it miss the contact with the extruder holder, I ermember you had this issue. Did you reprint the extruder holder to fix it ? The very first mk2 delivered had some tolerance issues.
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Re: P.I.N.D.A. probe misaligned

Sun Jul 03, 2016 4:24 pm

What a great set of diagrams and explanations christophe, this should be made part of the official Assembly Manual or 3D Printing Guide!! 8-)

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Re: P.I.N.D.A. probe misaligned

Sun Jul 03, 2016 4:29 pm

^^ +1. Fantastic explanation!

prusayo
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Re: P.I.N.D.A. probe misaligned

Sun Jul 03, 2016 5:09 pm

christophe.p wrote:Thanks for pointing it Prusayo, I fixed the mess ;)

Yes there is not a lot of margin for the endstop, and most likely you can easily make it miss the contact with the extruder holder, I ermember you had this issue. Did you reprint the extruder holder to fix it ? The very first mk2 delivered had some tolerance issues.
I thought fw 3.04 was attempt to resolve this issue? I was waiting for official release before attempting. Why would extruder holder affect endstop sensor placement? I think I'm getting more confused now. I have never tried printing printer part yet either. I'm afraid I'd make it worse.
.

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Re: P.I.N.D.A. probe misaligned

Sun Jul 03, 2016 5:27 pm

Yes FW should fix that, as it will be possible to change the pinda probe positions.

The extruder holder push the X-endstop with a small part. In the very first mk2 sent, there were some issue with sizes, I add to reprint it because the heater was not fitting well into the holder. There were some reports of users that had to add a little part of plastic on this small part to be able to properly trigger the endstop, and this may in some case add additional offset on the X-axis. Now everything is allright, sorry to confuse you.

However I'm glad my Visio drawing helps people ^^
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prusayo
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Re: P.I.N.D.A. probe misaligned

Sun Jul 03, 2016 10:51 pm

christophe.p wrote:The extruder holder push the X-endstop with a small part. In the very first mk2 sent, there were some issue with sizes, I add to reprint it because the heater was not fitting well into the holder. There were some reports of users that had to add a little part of plastic on this small part to be able to properly trigger the endstop, and this may in some case add additional offset on the X-axis.
I'm not sure what you mean by "extruder holder". Are you referring to X-carriage:
http://manual.prusa3d.com/Guide/3.+X-axis+assembly/105
(Step 2, red)

This printed part?
https://github.com/prusa3d/Orignal-Prus ... rriage.stl

I checked extruder manual section but don't see a part that touches the x-endstop but may I'm misunderstanding something. Thanks.

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Re: P.I.N.D.A. probe misaligned

Mon Jul 04, 2016 5:25 am

Yes you're right, that's the part I was talking about.
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