Fix UM2 bed oscillation

[restinpieces 3]

Since I used my UM2 for the first time I always had the problem, that the bed started to oscillate.

Mainly on large prints with long straight runs. Some print could be recovered If I got it in time and turn the speed way down (50-60%). But a lot of prints where lost :(

Finally I got around to test an idea I had for a long time. I drilled holes in the aluminum plate and cut threads in the holes. Then I screwed some aluminum U-profiles I had laying around to stiffen the bed. The U-profiles should be starting right at the backside of the plate and be as near to the linear bearings as possible.

Here is a picture:

I had to change the Z-end stop screw in the back from 20mm to 25mm.

The amazing thing is, not only can I print large prints at full speed without oscillation, overall from small to large prints the results got A LOT better.

The hack is pretty easy. The biggest problem is to open the UM2 to demount the bed. That's a real PITA.

Overall I'm happy this turned out so good.

Edited March 16, 2016 by Guest

[IRobertI 429]

Nice. I've been thinking about doing something like this for a long time as well but I've just never gotten around to it. Maybe I should finally get my ass in gear and do it.

[danilius 117]

Did you have to fiddle around with the limit switch at all? There isn't all that much clearance under the platform that I can see on my UM2.

If you are shy of opening the case, then an epoxy glue like araldite will do the trick. Just clamp the beams in place while drying or wrap some painters tape around it it all until dry.

[SandervG 1,011]

Thank you for sharing this fix with us!

[neotko 1,361]

How do you change the z screw? Dissasembling the motor? Or new motor?

Edited March 17, 2016 by Guest

[00D00B 58]

How do you change the z screw? Dissasembling the motor? Or new motor?

 

He's talking about the screw from the Z endstop, not the motor one. It's just right under the bed platform.

Congrats, your solution seems to be pretty intresting ! Maybe some flatter aluminium profiles would be more acurate ?

[restinpieces 3]

 

How do you change the z screw? Dissasembling the motor? Or new motor?

 

He's talking about the screw from the Z endstop, not the motor one. It's just right under the bed platform.

Congrats, your solution seems to be pretty intresting ! Maybe some flatter aluminium profiles would be more acurate ?

 

Correct.

I used what I had laying around. But, the higher the aluminum the stiffer the bed. A wide but flat aluminium does nothing to the bed stiffness.

There is also the option to put the profiles on the top of the bottom plate, between the plate and the heated bed. But that would need some more fiddling around.

[IRobertI 429]

On the top is where I've wanted to put them. I was also thinking about making them clamp around the bearings for extra rigidity.

[izzy 32]

To save demounting the platform and screwing them on what about bonding them on using CT1 a silicon type builders sealant that doesn't shrink or smell?