Saddle shape mesh (V-Core 3.1 500mm)
I started with a big dip at "D" after following the advice from the video I ended up with a saddle shape. It looks like the bed is bowing down at the unsupported corners.
The total range is 0.390mm when heated to 70C
I verified that the Y rails are parallel to eachother and they were screwed in the correct order.
Any suggestions on how could I improve this?
10 Replies
absent-sapphire•15mo ago
i have a really similar looking mesh, let me know if you find any resources. i was hoping for some collection of "this shape? this problem!" but i have been unsuccessful so far.
absent-sapphire•15mo ago
One thing i noticed on my machine, after loosening the screws section by section to check for any forces being applied...the Y rails are visibly pushed out by the gantry when at y=0, indicating there's some sort of compression on the gantry when at Ymax (hence the saddle).
deep-jadeOP•15mo ago
I'm also suspecting that there is some squishing of the X gantry when it's mowing forwards and backwards. I think when I moved the front mounts up and down, but the back stayed the same then the distance at the front would have also changed, but I don't know if that would cause this much of a difference
absent-sapphire•14mo ago
i've been working on this a bit and can give you some updates with what did / didn't work....
i DID loosen my x linear rail screws all the way and only retightened about 7 of them (gently, as suggested in the video that is shared quite a bit) and it didn't really make a difference.
i've done some voodoo magic to widen the back of the printer and i'll see if it works. i'm concerned it has put the whole frame under a bit too much tension, but we'll see.
more later once i fix it
If this can be reproduced also with a heated-up printer - why not "fix" it with some layer of tape on the magnet sheet?
absent-sapphire•14mo ago
(not OP) i've gotten it to .315 (500mm) but it's still a saddle. i ended up
- loosening everything to let the gantry get to something ....less tensioned around
- loosened the linear rails and gently retightened
- made smaller adjustments.
i'm still unclear why there's a saddle. i might have to be content with .315 and start printing to see what happens.
absent-sapphire•14mo ago
@beejayf at first i thought it was dumb, because i wanted it to work "correctly". then i remembered "it's not stupid if it works". thanks for the tip...now just a touch above .2.
absent-sapphire•14mo ago
hey,
How did you manage to lower the back extrusions ? i couldn't seem to be able to do it. Thanks
absent-sapphire•13mo ago
i didn't lower the back extrusions, i raised them. it was a relative pain (takes more screws / unscrews) compared to moving the front. i am by no means an expert but i think that if you're having to push so much on the front corners such that they really want to snap back in to place it's worth the time to back up a bit and check the frame is square and the feet are level.
i have a little bit of sag in my back corners but it is not affecting anything - i printed a perfectly flat .2mm first layer on the full 500x500 - the mesh just handled it.
the gantry also may not have been seated all the way in the end pieces. i took the ends off, put it back together, and the front ends stopped wanting to push out when y=500 (and front corners A, B were detached)