ronald.t6
Posts: 2
Joined: Feb 02, 2019 11:12 am
Contact: Send private message

Printer loosing home point?

Feb 16, 2019 4:37 am

I just built a mk3 and I have the latest firmware.

I do initial calibration and everything is fine. I do a test print of a large cube to set the live Z during the first layer. Get it looking nice and then stop/cancel that print so I can try print something I actually want. I cancel the print by pressing the knob and scrolling down to stop print. So far everything works as it should.

Go and start the new print and the nozzle doesnt go to the 'home' position on the X axis. So when it does the 9 point calibration the first point is ok (it is somewhere along the front edge of the print bed but not necessary to the left). When it does the second or third point, the pinder probe over hangs the print bed and when it goes down the nozzle digs into the print bed. Then I get an error about levelling failing and check if nozzle is dirty. Its like it forgets where the home point along the X axis is to start the first of 9 point in the correct position.

Ive tried turning the printer on/off and starting a new print and doesnt work - same issue where the 9 points are right of print bed so when it gets to the second or third point the probe isnt over the print bed and the nozzle sinks into the print bed.. When I go to auto home it is somewhere at front right of the print bed!! When I go to move axis the 0 point is towards the right...

The only way to 'reset' it is to do the self check again. Once that is done I can print and it works fine.

Whats going on? I dont think the belt is jumping a tooth or anything - doesnt sound like it. The grub screw on x axis motor is tight. I loosened the screws at the back of the x axis bearings slightly. Nothing has helped.

I now have a bunch of dents in my print bed now on the front right corner :x

ronald.t6
Posts: 2
Joined: Feb 02, 2019 11:12 am
Contact: Send private message

Re: Printer loosing home point?

Feb 16, 2019 4:48 am

edit:
Did an entire print of the prusa logo and then when I do it the second time it works fine. The printer homes the nozzle after the print. It seems there is only a problem after i cancel the print...

max.b10
Posts: 3
Joined: Feb 11, 2019 3:59 am
Contact: Send private message

Re: Printer loosing home point?

Feb 18, 2019 5:29 am

The exact same thing is happening to me! Finished assembling the printer today, test prints went fine, but when I stop a print through the menu or the printer cancels a print on it's own, the home position is lost. I have dents in the front right corner, just like you, from where the printer dug the extruder head into my steel print sheet, and gouges in my heating bed from when I thought maybe it was doing a test that required me to not have the sheet on the bed. Did factory resets, flashed firmware to lastest version, lossened screws on the back of the x-axis extruder plate. Nothing has worked.

I'm getting the exact same errors. This is the MK3S model.

Any resolutions? The whole point that I bought a Prusa was for the fail safes, and those are NOT working.

User avatar
tim.m30
Posts: 903
Joined: Sep 09, 2018 11:03 pm
Answers: 20
Contact: Send private message

Re: Printer loosing home point?

Feb 19, 2019 8:33 am

@Max -- Did you perform the manual step of setting the PINDA height before you ran the Wizard calibration? If the PINDA isn't set correctly, especially too high, the nozzle will do exactly as you've described.

See Step 3.
https://manual.prusa3d.com/Guide/9.+Pre ... 53?lang=en

@Ronald -- After a print, the extruder is moved up and to the right, away from the print; it isn't "homed" ... Home is the lower left front of the bed.

jon.e3
Posts: 4
Joined: Oct 10, 2018 9:37 pm
Contact: Send private message

Re: Printer loosing home point?

Mar 06, 2019 5:59 pm

I am running into this as well .

I assembled the printer a week and a half ago and have been using it everyday , Yesterday I installed a set if Igus bushings to the axis slides rods and when I went to recalibrate it I had some troubles and had to start over several times , I finally got it set up and it checked out ok , as soon as I went to print I noticed it did not go home first it stayed in the middle of the work plate up front and tried the leveling , of course it went all the way to the right and stalled out and said there was a Z level failure ??

I can go through the whole process again and it will check out but as soon as a print is started it will fail ..

I am thinking that somehow it remembers where the extruder head was in relation to the E steps on the axis motor and when I removed the belt to install the bushings it keeps trying to revert to this position ??

User avatar
tim.m30
Posts: 903
Joined: Sep 09, 2018 11:03 pm
Answers: 20
Contact: Send private message

Re: Printer loosing home point?

Mar 06, 2019 10:24 pm

The position logic is pretty simple. Power off and back on the printer has no clue where it is and must find home. It does this by moving the bed fully back until the motor stalls, and the extruder to the left until the motor stalls. Then it moves the Z-Axis down until the PINDA switches off. That point is 0,0,0 in the coordinate system. If at any time during a print the extruder is bumped, the bed bumped, or the motors stall, the printer is lost.

This is why the printer "homes" before every print. It needs to know where to start, just in case you moved something manually; which is very easy to do removing a part, cleaning the bed, etc.

stephen.h14
Posts: 132
Joined: Dec 13, 2017 4:55 pm
Contact: Send private message

Re: Printer loosing home point?

Mar 07, 2019 12:47 am

As I understand it, if you have an axis that is bound up, the printer thinks it's hit the hard stop and stalled when it might actually be out in the middle of the print bed. So watch out for a binding axis if your printer can't find home correctly.

jon.e3
Posts: 4
Joined: Oct 10, 2018 9:37 pm
Contact: Send private message

Re: Printer loosing home point?

Mar 07, 2019 8:28 pm

I understand what your saying ..

Whats actually happening with mine is when the printer stops by aborting the print the extruder runs up a few millimeter then over to the left a few millimeters , if you don't actually move the extruder manually over to the left it will start the leveling process from the point it stopped at , In other words its not finding home first like it should .

My mk3 still does this every print but my mk2s does not , Im wondering if its a change in the firmware that it might need ?

User avatar
tim.m30
Posts: 903
Joined: Sep 09, 2018 11:03 pm
Answers: 20
Contact: Send private message

Re: Printer loosing home point?

Mar 08, 2019 12:50 am

Check your startup gcode, it might be missing the initial G28 W ...

tim.m36
Posts: 1
Joined: Feb 18, 2019 6:25 pm
Contact: Send private message

Re: Printer loosing home point?

Mar 08, 2019 1:02 am

would love to see an answer on this. I am on my 3rd day of printing with this and im running into this issue as well

Return to “Assembly and first prints troubleshooting”

Who is online

Users browsing this forum: sebastien.l3 and 3 guests