Inconsistent bed adhesion and printing quality
I've been having some problems with my MK4S recently. For a long time it was working perfectly the print reliability has slowly deteriorated over the last few months. It started with some random failures: stringing, bad support interfaces and just generally failed prints. It's been a few months since it started and I did a lot of tweaking, rebuilding, and tweaking of slicer settings. Since then it's been a few months and haven't done much printing since. Today, I got some inspiration to test printing benchys at different locations on the build plate. Interestingly, that actually seemed to make a difference. The picture below is an attempt at illustrating where each print was located on the build plate during printing.
Out of the 7 prints I started only 2 finished and they looks to be about the quality I had come to expect from my 4S! Interestingly, these two prints were both very near the center of the build plate.
All of the rest of them either ended up stuck to the nozzle or generally just detached from the build plate at approximately 10-15% through the print.
All of the seven were printed in approximately the same operating conditions with identical slicer settings:
- 0.4mm hardened nozzle
- silicone sock on the hotend
- stock nextruder
- black 1.75mm PETG Prusament
- slicer settings: unmodified (other than supports) prusament PETG, 0.20mm SPEED profile, MK4S 0.4 nozzle printer
- firmware: 6.2.6
- brand new textured powder-coated build sheet from Prusa
Any advice is much appreciated. Im more than happy to run some other test prints, disassemble/re-assemble components or just generally try things out. Thanks!
RE: Inconsistent bed adhesion and printing quality
Did you print these parts in the image one after the other (by object) or all together by layer?
RE: Inconsistent bed adhesion and printing quality
Each was printed individually (by object) one after the other with a re-slice and export for the new location
RE: Inconsistent bed adhesion and printing quality
Brand new build plate? Hmmm.
I suggest washing it with hot water and dishwashing solution, such as Dawn Ultra (in the USA). Make sure it doesn’t contain hand softener. I fought the same issues as you described until I realized that the Palmolive I was using was the problem! After switching to Dawn, the parts almost stick too well!
Best of luck!
MK4S/MMU3
Check there is nothing under the print sheet or stuck to the back. Lay a straightedge across the plate and check for flatness - If it's not too far off there are remedies but check first.
Cheerio,
RE: Inconsistent bed adhesion and printing quality
>> Interestingly, that actually seemed to make a difference
PETG is more prone to warp than PLA so adhesion matters.
There isn't consensus on the topic but IMHO cleaning the print sheet consistently (!) especially when multiple materials are involved is more tricky than it might look superficially. There are subtleties involved e.g. that pure IPA doesn't necessarily dissolve PLA residue (lacking water) and doesn't bind to fatty contaminants (as soap would do), just moves them around.
A spray can of a dedicated adhesive/separating agent was my most efficient investment in 3D printing, next a drier (15x more expensive but IMHO mandatory).
RE:
Flatness or Debris
- Before reprinting, I checked for flatness across the print sheet using some 30x30 aluminum extrusion. There are no obvious signs of warping or height changes
Cleaning/Adhesives
I did just purchase a spray bottle for cleaning (with IPA) the other day and am awaiting it's arrival. Is there a particular adhesive you typically recommend?
A dryer is currently on my wish list. For the time being I've been using sealed containers filled with some rechargeable desiccant to store my spools. Thus far I have yet to notice any oozing or popping/crackling.
Washing the build plate
- Per your instructions @largriff I cleaned the build plate with dawn, a soft sponge, hot water and powder free nitrile gloves. Then I let it cool and dry before attempting two new prints. The first, using the same gcode as a previous failure, failed almost identically. The failure is pictured below. The second, centered on the build plate, just like the other two centered prints, printed without issue.
RE: Inconsistent bed adhesion and printing quality
I wash my build plate with hot water and cheap dish soap, dry with plain tissue paper and then put the build plate on the printer and heat it with the heatbed,
keep your fingers off the build plate surface.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility.Location Halifax UK
RE: Inconsistent bed adhesion and printing quality
Looks clean! Still grabbing straws, now it makes me wonder if your heated bed is working properly. Is there any way you could check the temperature at various spots to see if it is close to what it should be? Perhaps the bed thermistor could be faulty, as well. That could explain the decreased quality.
A dryer will surely help, too, although I doubt that’s the root issue here.
I’m curious now! Let us know what you find.
Washing the build plate
- Per your instructions @largriff I cleaned the build plate with dawn, a soft sponge, hot water and powder free nitrile gloves. Then I let it cool and dry before attempting two new prints. The first, using the same gcode as a previous failure, failed almost identically. The failure is pictured below. The second, centered on the build plate, just like the other two centered prints, printed without issue.
MK4S/MMU3
RE:
I picked up a cheaper IR thermometer today and took some measurements at a set point of 85C. Turns out, it's a few degrees C off of the set point when the read out reports it's at the set point. See results below.
After this observation, I updated the first layer and other layers temperature set points for the Prusament PETG profile to 93C and 98C respectively. Turns out that was pretty effective. I managed to get a successful benchy at the same location as one of the other failures from before. During the print (~37% complete) I paused the print and measured a maximum of 91C and a minimum of 79C. It wasn't a perfect print- the outermost part of the hull raised off the build plate but otherwise it finished!
Long story short, I plan to order a new thermistor for the bed. Is this a common failure?
Thank you all in your help debugging this and helping me get back printing!
Those figures look pretty good - don't forget that heat (and so temperature) is lost from the exposed surface of the build plate - only where it is insulated by a print in progress will it rise all the way to the set temperature.
It wasn't a perfect print- the outermost part of the hull raised off the build plate but otherwise it finished!
Please show us the underside of that print.
Is there a particular adhesive you typically recommend?
PETG doesn't need separator (adhesive) with the satin or textured sheets, it does with the smooth sheets. Use a small amount of PVA glue diluted and spread with a wet paper towel.
Cheerio,