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JohnLS
(@johnls)
Active Member
MK4 denting build plates

I don't see this as a top level topic, so I'm starting a new thread with a title that is a bit more clearly labeled.  I received my MK4 as a kit a couple of months ago.  I assembled, upgraded firmware and calibrated and everything worked great from the first print. 

Since then, I started to notice small dents in my smooth build plate.  I monitored it closely, and it appears that the dents appear during the initial calibration step before printing.  I now have little divots all over the plate. Each time the printer calibrates I'm assuming that they also affect the calibration process, possibly making the problem worse?

Here's a picture showing the equally spaced dents:

And here from the gutter on the bottom edge of the plate:

I've reached out to Prusa via their contact page.  I'll update this thread with any steps that they ask me to take.  Or maybe a Prusa employee who's monitoring the forum can comment.  If you have the sames dents on your build plate please post a response to this thread.  If you don't have dents and your MK4 is working fine, I'd love to know that too.  That would indicate there is something specifically wrong with my printer and it will help the Prusa folks diagnose and repair the problem.

Cheers and happy printing,

John.

Posted : 15/11/2023 8:31 pm
Owens2303 and liked
simtr
(@simtr)
Member
RE: MK4 denting build plates

Are you sure they're dents and not bits of filament that could have oozed out when the head tapped the plate? I thought the same thing as you, but I was able to scratch them off with a bit of IPA and a fingernail.

Posted : 17/11/2023 9:06 pm
JohnLS and Zappes liked
JohnLS
(@johnls)
Active Member
Topic starter answered:
RE: MK4 denting build plates

Good suggestion.  I pulled out my microscope out for a closer look.  Sure enough the actual "dent" is more of a moon crater; a ring of compressed plastic material.  Given that I'll probably need to acquire a new plate anyway, I took out some acetone and some super fine wire wool and took off the raised material.  What I found was that most of the "dents" could be smoothed out.  Only about 10% were actual dents in the plate.  So, not zero, but a lot better than I originally thought.

I do most of my printing with PETG, which adheres really strongly to the smooth plate.  The problem was I found that if used the texture plate with PETG, I lose adhesion during the print quite frequently.  That's probably why the adhesion's are so hard to remove.  Isopropyl alcohol doesn't touch them.  I used to print this way with my MK3S+ all the time with no issues.  But because the new print head sensor needs to touch the plate to calibrate, I don't see how this problem is not just a fundamental consequence of with the way the MK4 works.

Posted : 19/11/2023 9:57 pm
Crab
 Crab
(@crab)
Reputable Member
RE:

I'm surprised you don't find that PETG ruins your smooth plate.. It took a chunk of PEI off my smooth one. Do you use a release agent with PETG? I found the texture plate excellent with PETG, but if you have a new texture plate, you might want to scrub a film off it from manufacturing with soap and plastic sponge.., once I did this my texture plate worked really well, unless I had a small surface area on the PETG and then I just added a bit of glue stick.

 

Posted : 20/11/2023 1:07 am
JohnLS liked
Zappes
(@zappes)
Estimable Member
RE: MK4 denting build plates

You should really have a try with the satin sheet. I originally only bought that for PETG, and it works brilliantly with that material - but I found out by accident (forgot to swap sheets) that the satin one is also really great for PLA. I use the satin sheet exclusively now and only pull the textured one out of storage if I want that particular surface structure on my print for aesthetical reasons.

My models on Printables
Posted : 20/11/2023 9:18 am
LilyPink and JohnLS liked
blauzahn
(@blauzahn)
Reputable Member
RE: MK4 denting build plates

I also mostly use the satin-sheet. If I hadn't put the foiled and the textured sheet into its sleeves, they would by now have gathered a lot of dust.

 

Posted : 20/11/2023 6:37 pm
LilyPink and JohnLS liked
LilyPink
(@lilypink)
Active Member
RE: MK4 denting build plates

It clearly states not to use the smooth sheet with the higher temp / sticky materials like petg / abs / pc etc  always use the satin sheet for those,,, and I always use glue to protect it and it ensures 99.9% success rate when printing smaller / taller items.   like mentioned above, Only use textured for specific surface finish on front plates of models if needed.   

There is a fix mentioned in another thread later on about Z-height adjustments being made to lower the Z-offset from its calibrated reading, pushing the filament further into the textured bed to get the textured finish to show over the bottom fill pattern.  Easily done but another after thought on the touching nozzle idea in my mind, I don't like all the waste deposited on my bed 20 times a print either, it has to push against the bed somewhat to gain feedback, so eventually this will wear through the coating I would imagine,  how long that takes over normal bed wear anyway is down to trials and testing I guess now, but hopefully they've found this doesn't make any negative effect during the life of the bed coating itself.

Posted : 28/11/2023 2:42 pm
TomasK
(@tomask)
Member
RE: MK4 denting build plates

I just had similar issue - new printer (after 8 printouts only), printing with PLA only - I was changing filament to different color (so the nozzle did heat up), then selected pre-heat to PLA (to pre-heat the bed as well) and then started new print via PrusaSlicer - not sure what was exact temperature during bed levelling (if 230 or 170 degrees Celsius), however after the print I did notice having 9 holes in the PEI sheet in places where nozzle was probing - see attached photos.

Posted : 02/01/2024 11:50 pm
Zappes
(@zappes)
Estimable Member
RE: MK4 denting build plates

I have similar structures on my sheets all the time, but until now, they always were specs of filament, not holes. Not saying that this is the case for you, but I really couldn't tell the difference from a picture. I actually thought mine were holes, too - then I took a scraper to to sheet to check if if could perhaps smooth the problem out. That would probably be a total waste of time, but I assumed that the sheet was b0rked anyway, so I experimented. Well, it turned out that my "holes" were little nozzle-shaped rings of plastic I could simply scrape off.

If, what's totally possible, yours are actual holes in the sheet, I suggest replacing it with a satin sheet. It's just the best Prusa has to offer and I really don't know why they still use the smooth sheets as the default that's packed with the printer.

My models on Printables
Posted : 03/01/2024 12:17 pm
JohnLS
(@johnls)
Active Member
Topic starter answered:
RE: MK4 denting build plates

Wow, lots of great discussion on this topic.  Just to wrap up the outcome from my perspective.  

After sending pictures to Prusa support (very helpful) we determined that indeed the majority of the dents were in fact ring shaped residue.  There were a couple of actual dents, but only a small number.  I was unable to successfully scrub off the residue without damaging the smooth plate, so I ordered a satin plate as recommended by several of you.  The satin plate is actually awesome.  No adhesions or denting, PETG & PLA parts stick well and release easily.  Highly recommend that folks get one and that Prusa makes it the default plate for new printers.

Also, the note about scrubbing the textured plate with soap and water.  Brilliant! I could not figure out why models kept losing cohesion, but now my textured plate is actually trustworthy to print on.

Posted : 04/01/2024 12:30 pm
Cloud1983
(@cloud1983)
Estimable Member
RE: MK4 denting build plates

Interesting, you have exactly the same bright bubbles/dots on your smooth PEI plate as I do. I contacted support with this and got a replacement plate. But I can see from your photo that I'm not the only one with this. I continue to use the sheet and it still works fine.

Posted by: @johnls

I don't see this as a top level topic, so I'm starting a new thread with a title that is a bit more clearly labeled.  I received my MK4 as a kit a couple of months ago.  I assembled, upgraded firmware and calibrated and everything worked great from the first print. 

Since then, I started to notice small dents in my smooth build plate.  I monitored it closely, and it appears that the dents appear during the initial calibration step before printing.  I now have little divots all over the plate. Each time the printer calibrates I'm assuming that they also affect the calibration process, possibly making the problem worse?

Here's a picture showing the equally spaced dents:

And here from the gutter on the bottom edge of the plate:

I've reached out to Prusa via their contact page.  I'll update this thread with any steps that they ask me to take.  Or maybe a Prusa employee who's monitoring the forum can comment.  If you have the sames dents on your build plate please post a response to this thread.  If you don't have dents and your MK4 is working fine, I'd love to know that too.  That would indicate there is something specifically wrong with my printer and it will help the Prusa folks diagnose and repair the problem.

Cheers and happy printing,

John.

 

Posted : 05/01/2024 1:19 am
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