Problems with first layer being too high off of the plate  

RE: Problems with first layer being too high off of the plate

With

With all of my MK3S+ machines, I can hit print and walk away.  With the MK4, I have to check every print a few minutes after it starts, because they just aren't reliable. 

Yep, welcome to the club. 

Not having to do live a calibration every time I swap nozzles or sheets is nice but once the live z calibration was done, it was hit print and walk away.  With my Mk4s I find I have to manually lower the nozzle almost every time, at least with textured and satin sheets--which are the only ones I'm using. 

RE: Problems with first layer being too high off of the plate

I have noticed the same, but not to the degree where the first layer is not sticking to the bed. I agree, however, that the problem is likely due to the pieces of melted filament on the nozzle causing false readings. I believe they need to rethink how the homing procedure works in order to reduce the false readings. Currently, I wipe the nozzle with a paper towel right before it starts the homing procedure to try and reduce and false readings, but that does not work consistently every time. 

Perhaps they could heat the nozzle hotter and retract the filament before doing the homing procedure? This should help reduce any oozing and ensure that the filament is fully melted when doing the probing.

RE: Problems with first layer being too high off of the plate

I also made this experience with textured and satin sheets. This gets even worse with a 0.6 nozzle.

But there is light at the end of the tunnel. I just installed the "5.1 stable" software and my first prints had a good 1st layer on textured sheet.

Can anybody confirm this?

RE: Problems with first layer being too high off of the plate

I don't see any difference between 5.1 and previous versions

RE: Problems with first layer being too high off of the plate

If you think that heating the filament hotter and retracting before it does the bed probe will work better then simply modify your start gcode to do so and test your theory.  You don't have to wait on Prusa.

I don't have a Mk4 to try it on (thankfully).

RE: Problems with first layer being too high off of the plate

that would really suck with the MK4.. I still have the MK3S+ and was originally going to upgrade to MK4.. and you are right.. Once my Z is dialled in on my textured sheet (I use exclusively now.. just add glue for PLA).. it is "just print and walk away".. almost never a failure.. I'd be really disappointed if the MK4 didn't fix that.. wonder if separate click probe would not have been better.

RE: Problems with first layer being too high off of the plate

To be honest, I can't verify that this is actually a common problem. My MK4 has not shown this kind of behaviour even once - bed levelling and first layers are a 100% reliable here.

RE: Problems with first layer being too high off of the plate

I just started having this issue with 5.1.  I notice on this that it went back to only probing the print area vs. the whole sheet.  When it was probing the whole sheet I didn't have any issues.

I wonder if there is a setting I can change to have it go back to probing the whole bed.  I'll have to research it a bit.

RE: Problems with first layer being too high off of the plate

I haven't really noticed any difference from 5.0.1 to 5.1.0. To be clear, my issue is not so bad that the print fails to stick. Instead it just appears a tad too high occasionally where the texture of the satin sheet does not come through, and instead I could see the lines from the first layer. I'm running a 0.6 size nozzle if that makes any difference.

RE: Problems with first layer being too high off of the plate

I haven't loaded 5.1 yet, I'm still on 5.0.1, but my layers definitely sometimes are high enough up to cause problems, where the pieces start warping up off the bed.  It's always super consistent too, if they are high, they will be high evenly across the whole bed, so it's probing consistently, it's just not getting the home for Z correct.

RE: Problems with first layer being too high off of the plate

FYI I ran thru the initial calibration again and now my issue seems solved.  Not sure if something got lost when I did the firmware upgrade.

RE: Problems with first layer being too high off of the plate

I spoke too soon as I am also having issues with prints warping off the sheet as well. I noticed with 5.1.0 that at least the printers are consistent and always are too high off the sheet. My workaround has been to hold the knob down when the print starts and manually adjust the z-level by -0.10 or more. This shouldn't be needed, but at least a workaround until they fix this issue.

RE: Problems with first layer being too high off of the plate

Just wanted to jump on here.  I too see inconsistent first layer heights.  I will work to tract down the cause, but as this is day 3 with the MK4 upgrade, it will take a while.

Has anyone else come up with a workaround?

I am also on the fence about binary gcode, because as others have posted, the printer hangs 100% of the time when attempting to print a manual multi color binary gcode file from the USB drive.  

RE: Problems with first layer being too high off of the plate

Has anyone else come up with a workaround?

The workaround is to babysit the printer and manually lower live Z once it starts the print (after bed leveling). I lost two prints this morning after an hour (parts came off) because I got distracted and wasn't there to manually lower the nozzle for the first later and let the prints continue hoping for good luck — in vain ☹️

RE: Problems with first layer being too high off of the plate

Wonderful.  It really sucks that I pontificated with the MK4 upgrade because I couldn't see how the load cell method could overcome all the inconsistences of the build surface, only to find out that maybe I should have waited longer.  To be honest, my old MK3 needed an overhaul anyway, but still.

I'll give the live Z adjust a try.  

Luck to all of us. 

RE: Problems with first layer being too high off of the plate

I don't have any of these issues with mine.  The first layer is perfect every time.  I just make sure the nozzle is clean before the print starts.  Therefore I suspect something else is going on. 

The first layer is way better than on any off my MK3s. 

RE: Problems with first layer being too high off of the plate

Brian, on textured sheets? Zero problems for me on smooth sheet--which I pretty much never use. 

RE: Problems with first layer being too high off of the plate

On the Satin sheet.  I unfortunately don't have any textured sheets to try and see if I have the same problem.  I have used the smooth PEI sheet a few times without issue for some PLA, but I print PETG 95% of the time and that seems to work best on the satin sheet. 

In the past I had a few first layers not turn out and I discovered that oozed filament on the nozzle from a previous print can make the Nozzle pick up incorrectly on the sheet.  PETG seems particularly bad for oozing so I just make sure the nozzle is clean before each print and it always works really well.

I'm not sure why Prusa doesn't design a brush into the printer that it could automatically clean the nozzle before each print.  It seems like it would be super easy.  Maybe I'll put that onto my to do list. 

RE: Problems with first layer being too high off of the plate

I've had my MK4  since July and just ran into this problem last week.  Being relatively new to 3D it took a while to realize this was the problem.  I appreciate all the suggestions on this thread.  I ended up doing a thorough cleaning of the nozzle, re-installed firmware 5.1.2 and did a full recalibration.  While I was at it I retentioned the belts, though that was not the problem they needed it.  First layers are now back to perfect.  I'm going to pay much more attention to cleaning the nozzle in the future.  I agree that it would be nice to have a cleaner built into the printer since the Z is calibrated at the start of every print.