Solved Weird problem with magnetic arms and tool fan

[skayred]

Hello, I have a Delta printer with magnetic arms.

Some time ago, i started having a weird problem - when I move effector in X-Y plane, fan RPM varies depending on the position - for example, in 0/+40 it nearly stop, while in the center it has about the normal RPM and works pretty loud. I have replaced the fan with the new and quiet one, after some time I have the same problem again. When I unscrewed the fan, I have found out, that the fan behaves so when it is located close to magnets, it seems that magnetic field makes the bearing loose, until the friction goes to high - that explains the noise.

My effector looks so:

Did someone have the same problem? Is there any workaround without changing the effector design?

[alankilian]

@skayred

You could try shielding but it might be expensive:
https://www.youtube.com/watch?v=oxg_hCvXSrw

Or you could try rotating the fan into different orientations and see if it's less sensitive in some orientations.

[jay_s_uk]

@skayred make sure you alternate the arms. There should be one with a north magnet, then South then north and so on.
If you have Haydn rods, he puts a stick at the end with a north magnet so just alternate where the sticker end is

[skayred]

@alankilian hello, did i understand correctly, that i should try rotate the fan let's say 90 degrees counterclockwise keeping the effector position?

I was also wondering, should I give a try to the remote fan (connected with PVC hose), would that be sufficient for the hotend cooling? My effector is pretty small, so there are no other places where I can mount the fan

[skayred]

@jay_s_uk yeah, I have Haydn's arms, so the result position should be like S-n-s-n-s-n around?

[alankilian]

@skayred said in Weird problem with magnetic arms and tool fan:

try rotate the fan let's say 90 degrees counterclockwise

Yes that's what I mean, but I think @jay_s_uk also has a good suggestion.

[jay_s_uk]

@skayred yes. It's a known thing with magball arms. If you have them all the same way the magnetic field affects the hotend fan

[skayred]

@jay_s_uk @alankilian I have done both - it worked, thanks! Life is a magic if I don't know physics well enough

[alankilian]

@skayred

GREAT news.

Send some images of good prints when you're done.
It's always nice to see success.

[skayred]

It actually started working way better with PLA as a side effect