build plate adhesion  

RE: build plate adhesion

Charles, unless this is just a venting post (that can be rather liberating :D) propbably a few more information are be needed if anyone has to try helping you. Maybe share the 3mf file? Show a picture of what happens on the plate? Which filament/brand are you using, etc. etc.

I print mostly PCBlend and PETG (prusament) inside a prusa enclosure on my mk4 (now mk4s) and using tabs (but only on critically shaped objects) I don't have any issue at all... so there is a decent chance that the collective forum wisdom can help with your problem...

RE: build plate adhesion

The Picture I provided is the box (did not print the walls) on the build plate.  I am just printing in Elegoo PLA Black.   I have posted my .3mf file here Gridifinity-3x4-60mmBox-Supports-MK4

I would be happy to provide any other information.  or try new things that i have not done. 

Thanks,

Charles

RE: build plate adhesion

Since the same STL works perfectly on another printer with default parameters and no brim, this strongly suggests the issue lies in the Prusa's specific calibration (likely Z-offset/First Layer Cal), a slicer setting specific to the Prusa profile, or a subtle hardware issue with the Prusa's bed leveling/probing system. My money is on needing an absolutely dialed-in First Layer Calibration.

Posted by: @cminer87

This has been happening for a while.  It happened on my MK4 and still happens when i upgraded my MK4 to MK4s.   I have tried different build plates (cleaned build plates) different temperature for both the plates and filament.  I have used different filament, dried filament,  printed it in my enclosure and out of my enclosure. I have done the print with full brim, brimmed just the 4 corners, and no brim.   

I am at a lost.   The same STL works perfectly on my other printer (non Prusa) with default parameters , with no brim.

Thanks,

Charles M. Miner

RE:

My guess is that those drag lines are because of thermal expansion of the bed.

The printer makes a bed mesh before starting the job, On the 3mf  file of user cminer87 you see that it takes almost two hours to complete the bottom of the model (6mm. height). During this time the bed expands upwards around the periphery as the whole frame warms up, but the bed mesh values were taken two hours earlier when the bed hadn’t got time to curl upwards. Therefore, the nozzle travels too low as it goes away from the centre, making those drag lines. You’d think that it wouldn’t matter much as we're already a few layers above the plate, and yet this isn’t the case. I’ve seen something very similar happen on my Vorons printing large parts that cover a significant part of the printing area, taking a lot of time to complete each layer.

If the problem doesn’t arises so much ( or nothing at all) with a printer of another brand, then it must be a different kind of bed and/or different bed size, maybe printing faster and possibly with a Z-offset on the centre a bit too high, Many factors involved.  

When I have these kind of issues on my printers, I  raise manually a bit the Z offset (10-20 microns ) every other layer until I see that the drag lines disappear progressively. It’s a tiresome and imperfect fix because then the centre prints too high, but this isn’t usually so visible as those ugly drag lines,

Please show us the underside of a failed print.

If the print sheet is genuinely clean then the next most likely cause is a draft or other source of cold air.

Cheerio,

RE: build plate adhesion

The gridfinity boxes are surprisingly hard to print. I tried to start a thread specific tips on the topic, but it didn't take off much 😁

https://forum.prusa3d.com/forum/postid/742412/