3D printing magnetic build plate disengaging

Hi all, any advice/help would be appreciated. I’ve had my 250 in storage while I go thru several moves, but I pulled it out to start printing shelves for my new place. I’ve now printed this shelf three times. First two times it made it to 69% complete before the magnets let go and the bed shifted. The last time I enabled Z-hop, thinking that might be the problem (head hitting the object, moving it). It made it to 79% and failed. I’m using SM PLA, Cura slicer. I’ve tried the settings in Cura for both generic PLA and SM white PLA. Both failed. I can see that the print failed the middle of a layer (where the filament stops printing the object and goes off in a random direction). I’m using a .6mm nozzle (calibrated and set up in Cura) for speed. I’m using the generic fast profile in Cura with mods for the .6mm nozzle. I’m currently printing it again with the magnetic plate clamped down, but I’d love to know what is causing the plate shift. Thanks!

You can see here that it failed in the middle of printing a level. Thanks!

Big piece like that, very likely warping. Can try a brim. Doubt clamping will resolve the issue completely.

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Cool. I’ll try a brim next time if it fails again. Using a skirt currently. Crossing my fingers for the clamp. I also keep checking it. May need to buy a camera at some point to monitor the printer for these 10 hour jobs. Thanks for the advice!

The print sheet will only shift like that from the nozzle hitting the print. Settings like z-hop, and “avoid printed parts while travelling” are some ways to help, but ultimately you need to find the underlying cause, which is most likely warping like @snapUser said.

OK I ran it again with clamps, but of course @SnapUser was correct and it still knocked off the plate. I tried to film it with my laptop but of course the laptop went to sleep (?) and so I don’t have the film of what happened when it failed - just an hour and a half of it printing fine and then 3 hours of my face - who knows where the hell that came from!?!

So if it is warping, and that is pulling the plate off the magnets, what can I do. I understand the idea behind a brim, but it isn’t pulling off the plate, it’s pulling the plate off the base. I already enabled z hop, and the evidence from the last print is that it was in the middle of laying down filament when it failed, so Z hop wouldn’t have helped even if it had been engaged.

It’s so super frustrating that I’m trying to print something that fits on the plate but it won’t print. I can see if there’s a way to better clamp the plate down, but I’m not sure there’s a way to do it that allows it to move.

Here’s my solution to that: Magnetic print sheet fixation - #10 by Hauke

I have screwwd them with these holders

Now i hVe no shifts anymore

If you look at the last picture, its obvious that there is a lot of curling/warping on topside of object.

Reduce printing speed or maybe reduce only overhang wall speed. Not sure how good that setting works…
Lower printing temp
Increase fan speed if possible
Increase layer height - Counterintuitive but it seems to work

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Success! I used Kapton tape to tape the plate down. I also reset the following parameters in Cura -

Layer thickness from .35 to .5 mm
Bed temp after first layer to 50c
Nozzle temp after first layer to 190c
Fan speed to 50%
print speed from 60 to 40
Infill density from 20-15%
Infell pattern from cubic to zig zag
Added a brim

So basically anything I could find on line about warping.

There was stringing, which was new, so I’ll have to sand it lightly.

HOWEVER, I also watched it as it was printing during the time when it failed previously. And I saw the control cable for the print head fall into one of the half-formed diamonds on the back side. I pulled it right out, but it is possible that was what happened - the cable got snagged on the print and pulled the build plate off. Right after the print was finished I pulled the kapton tape off and there was no flexing of the plate like I would expect if the print were warped. The plate was solidly attached.

Thank you everybody for your advice and help!


Hello Hauke. It says this model does no longer fit the A350T. Do you know what has to be changed to make it work for the current model? You don’t happen to have an OpenSCAD or so “source” file for these?

Hi sciss,
the change is the platform frame. The corner blocks have gaps where the metal frame fits into, and since that frame has changed already pre-A350T-times, modifications are needed if you do not own the Kickstarter version. According to Thingiverse, Cheshire11 remixed my design (which is already a remix): Snapmaker 2.0 A250/F250 Heat bed fixation bracket by Cheshire11 - Thingiverse I suppose that will save you your own modification. If the remix is not good (I cannot judge), I’m afraid I cannot provide any CAD files - I basically used this model: Snapmaker 2 Glass Bed Mounting Bracket by PoetikDragon - Thingiverse and cut away any excess using Windows 3D builder, so STLs is all I have.
I’ll check Cheshire11’s design myself when I have the Quick swap kit - In there is another (new version) frame, which will hopefully be much flatter than my original one, which I then would use as base for my printbed, forcing me to use updated blocks also. If I do not like the remix, I’ll do one myself. My starting point most likely then would be to find on Thingiverse other glass brackets that were made for the new frame and again cut away any excess.
Hope that helps!

My solution is to add an auxiliary fan to blow against the platform, because it is an i3 structure, a special nozzle can be made to divide the mountain later, so that the fuse can be better cooled and solidified, and LAC glue spray can also be used for better attachment to the platform.

I also went for the little screw clamps in the end, seem to work nicely.