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[Solved] Z-axis Homing Issue  

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Gelap
(@gelap)
Eminent Member
Z-axis Homing Issue

After a few successful prints with the Prusa Mini, it seemed to have lost its Z-axis location.

It looks like it starts doing the mesh bed calibration in mid air, instead of moving down to the bed.  I tried restarting it and doing a full factory reset. As soon as I showed Prusa support the video, they said the MINDA cable must have broke. 

I just wanted to post this here in case someone else runs into this issue.

Posted : 21/12/2019 6:44 pm
unlotto
(@unlotto)
New Member
RE: Z-axis Homing Issue

I'm seeing the exact same thing.

Posted : 22/12/2019 9:31 am
unlotto
(@unlotto)
New Member
RE: Z-axis Homing Issue

For me, it happened before upgrading to 4.0.1

The probe is lit up, and reacts when you put metal under it (turning off led).

Posted : 22/12/2019 9:55 am
Gelap
(@gelap)
Eminent Member
Topic starter answered:
RE: Z-axis Homing Issue

@unlotto - I am seeing the same thing.  

By all outward appearances, the sensor is functioning properly.  The probe's signal is either not making it to the main board, or being acknowledged by the main board.  I tried re-seating the connection on the board.  I have also examined the length of the cable and I do not see any obvious signs of damage or kinks in it's cable.  

I spoke with tech support and they said they are sending a replacement.  I'm a little concerned as the last time they sent a replacement part it showed up as an RMA order on my account the same day.  So far there is nothing showing the order was placed.  I'll give it a couple of days and contact again if needed.

Posted : 22/12/2019 6:28 pm
axel.s
(@axel-s)
New Member
RE: Z-axis Homing Issue

Hi!

After a 17-hour print i too now have this issue, but my MINDA works on the rightmost leveling points, as soon as it goes out to the left of the rightmost points the lights go out.

created a ticket, lets see what happens.

on 4.0.1, leveled successfully before on this FW.

Posted : 23/12/2019 8:12 am
axel.s
(@axel-s)
New Member
RE: Z-axis Homing Issue

Update:

The light on the MINDA goes on and off when moving the cable bunch from the extruder around, so cable issue confirmed.

Posted : 23/12/2019 8:25 am
Aaron C
(@aaron-c-2)
Active Member
RE: Z-axis Homing Issue

Unfortunately, after a successful long print, my Mini is now exhibiting this problem too. 🙁  I've only used the printer 3 or 4 times since receiving it.

Posted : 25/12/2019 4:04 pm
Gelap
(@gelap)
Eminent Member
Topic starter answered:
RE: Z-axis Homing Issue

@wiredprairie Sorry to hear that.  That's about how many time I used mine when the it happened.  The good news is Prusa support is awesome and I got a replacement MINDA Probe very quickly.  I'm hoping the first one was just a fluke, I'm about to start my third print since installing the replacement (42 Marvins over 19 hours should be a good test).  

Just a couple of suggestions for installing the replacement since there are no instructions at the moment.  This is mostly for anyone who hasn't done a 3D printer assembly beyond what's required for a new Mini.  I am not an expert and these are just my opinions.

  • Take pictures before starting to remove the old MINDA probe.  Specifically, move the print carriage to the furthest X / Z from the control board, the closest, and somewhere in-between.  You want to be able to see how the cable sleeve looks at each position.  It might also be useful to have a picture of hot-end cables.
  • Pay attention when you remove the wiring sleeve to how they cables are arranged.  In my case, the slack from the fan cable was managed with a loop hidden in the sleeve.
  • Note the notch the in the piece holding the exetrution motor.  The cable from the motor follows that notch to join the cable sleeve.
  • Install the zip ties, but don't tighten any them until you move the print carriage to the points you took pictures of before starting.  You should move the sleeve in the loose zip ties until it matches the pictures.  This will help make sure the bundle of cables isn't stretched when printing.
  • Snug is probably good enough for the zip ties.  You want the zip ties tight enough that the cables held in place and don't to move/rub while its printing, but not so tight the cables get damaged.
Posted : 25/12/2019 5:49 pm
rob.b11
(@rob-b11)
New Member
RE: Z-axis Homing Issue

I'm having the exact same issue with one of my Minis.  Managed 10 or so prints, had some flakiness with starting prints, and now the z-axis won't home. I guess I'll contact customer support :/

Posted : 27/12/2019 6:51 pm
Aaron C
(@aaron-c-2)
Active Member
RE: Z-axis Homing Issue

Chat/support mentioned they'd talked to 3 or 4 people the same day I contacted them had reported the same issue. 

Posted : 27/12/2019 8:54 pm
rob.b11 liked
Gelap
(@gelap)
Eminent Member
Topic starter answered:
RE: Z-axis Homing Issue

Hopefully it was just a bad batch of probes or one of the assembly worker was a little over zealous with tightening the zip ties.  I guess we'll find out.  I just wish I could rename this thread to append "/MINDA Probe Issue" to make it easier to find.

Posted : 27/12/2019 9:00 pm
rob.b11 liked
jochen.h
(@jochen-h)
Active Member
RE: Z-axis Homing Issue

I had the same issue last week. Contacted support yesterday and new MINDA is on its way. I originally started another topic but wanted to post it here as well. 

Posted : 30/12/2019 2:24 pm
unlotto liked
Trailer Alarms
(@trailer-alarms)
Active Member
RE: Z-axis Homing Issue

I was having the same issue. I uploaded a video, and they said the MINDA cable was bad. They shipped a new one, and I replaced it today. 

EXACT same issue as with the old sensor.

Not sure what to do now. I've added to my existing ticket.

Posted : 07/01/2020 1:55 am
Trailer Alarms
(@trailer-alarms)
Active Member
RE: Z-axis Homing Issue

Still having issue with new MINDA sensor. Now they think it an issue with my Y axis causing issues with my Z axis.

Posted : 08/01/2020 8:21 pm
Rat_Patrol
(@rat_patrol)
Trusted Member
RE: Z-axis Homing Issue
Posted by: @lyle

Still having issue with new MINDA sensor. Now they think it an issue with my Y axis causing issues with my Z axis.

Interesting. I'm having the same trouble. They are sending me a new Y carriage, what was your resolution.

Posted : 09/01/2020 4:29 pm
Trailer Alarms
(@trailer-alarms)
Active Member
RE: Z-axis Homing Issue
Posted by: @rat_patrol
Posted by: @lyle

Still having issue with new MINDA sensor. Now they think it an issue with my Y axis causing issues with my Z axis.

Interesting. I'm having the same trouble. They are sending me a new Y carriage, what was your resolution.

They sending me something, thinking maybe a bearing.

Posted : 09/01/2020 4:43 pm
Crawlerin
(@crawlerin)
Prominent Member
RE: Z-axis Homing Issue

With MINDAs acting up, even repeatedly after replacement, is it possible this is rather a software issue? That firmware gets bonkers after.... something. But then, people had it after factory reset too 🤔

Posted : 09/01/2020 8:01 pm
Aaron C
(@aaron-c-2)
Active Member
RE: Z-axis Homing Issue
Posted by: @crawlerin

With MINDAs acting up, even repeatedly after replacement, is it possible this is rather a software issue? That firmware gets bonkers after.... something. But then, people had it after factory reset too 🤔

There may be multiple problems, but my Mini's MINDA probe connection is definitely faulty.  I just received the replacement cable but haven't had time to replace it yet. 

Posted : 09/01/2020 8:18 pm
Rat_Patrol
(@rat_patrol)
Trusted Member
RE: Z-axis Homing Issue

Very well could be, only time will tell. 

 

In the mean time, I shimmed the one side of the bed in an attempt to get it level-ish manually, and I'm also running a .4mm first layer so there is some wiggle room there. 

Results also change with temp. The problem is bad with PETG, not so bad with PLA, ABS is in-between.

Posted : 09/01/2020 9:29 pm
Trailer Alarms
(@trailer-alarms)
Active Member
RE: Z-axis Homing Issue

SOOOOOO...

I got new bearings in today for the Y axis. I replaced them, and we are back up and running.

Posted : 14/01/2020 2:24 am
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