Stepper Motor Rusting in Humid Environment

[Celestia]

 

Hello everyone, I have a question I'd like to ask for your thoughts on.

The workshop has high humidity. A stepper motor on a spare machine was left unpowered for a week. When I turned it on again, the motor made a rattling noise and jerked while running.

Upon disassembly, I found rust on the shaft extension and bearing area. Turning the shaft by hand felt very difficult. After removing the rust and applying rust-preventive oil, the bearing is still making noise. Is it possible that the stepper motor shaft wasn't surface-treated?

Are there any motors that come with a factory-applied rust-preventive coating that you would recommend?

 

[McCosch]

I found something specifically for damp rooms; maybe this will help you (unfortunately, it's in German)....https://www.omc-stepperonline.com/de/p-serie-ip65-wasserdicht-nema-17-schrittmotor-2-0a-0-59-nm-83-57-oz-in-17ip65-06

[polyneutron]

If you cannot avoid putting the printer in a humid condition, Coat the insides with a light oil or transmission fluid then wipe it off. Especially if you can take them apart. Before I retired, the company I worked for accidently dropped some rusty parts in a bucket of used transmission fluid, when he retrieved the parts and wiped them off, no more corrosion. He assembled the machine and it didn't rust again for years.  

[Repman]

From the chemical side of view:

If the motor rusts within a period of time from one week, there could be also some kind of acid in the air. I ´ve seen that after a fire with PVC cables in an oven. Everything in the room which was from iron got a red shining patina in a few days. The burned PVC produced HCl (Hydrochloric acid) which is in combination with humidity very aggressive, even in low doses.
The same effect was observed during development of the Nevermore Carbon Filter (https://github.com/nevermore3d/Nevermore_Micro#sourcing-the-proper-acid-free-carbon) if users did not use acid-free carbon as filter material.

Is the motor the only part which is oxidized like this? Do you see rust on other parts like screws too? 

Edited April 22 by Repman

[Penatr8tor]

Gonna chime in here...

Firstly... if there's one thing you should prioritize when setting up a 3d printer is to place it in an environment that is as dry as possible. Moisture is the absolute enemy of everything you want to achieve with filament based printing.

That said... stepper motors are cheap. Throw away the bad one and install a new one. I wouldn't spend time trying to rebuild a 10 dollar motor.

Not trying to be a jerk here just pointing out what to me seems obvious. 

[McCosch]

correct

[polyneutron]

The moon 0.9 motors I bought for the X and y. In retrospect I should have purchased all 6. They went up in price. I will get 4 more at a later date

 

[McCosch]

[NikosSprocket]

Both Voron 2.4s have LDO motors and running without any issues for more than 5 years; lost count! They are located in the garage with average humidity into the 50%s. No dehumidifier, no rust.

[mvdveer]

5 hours ago, NikosSprocket said:

Both Voron 2.4s have LDO motors and running without any issues for more than 5 years; lost count! They are located in the garage with average humidity into the 50%s. No dehumidifier, no rust.

Same here - all my printers (13 in total) are in the garage (Melbourne Victoria, Australia) with high humidity at times. A mix of LDO and Moons motors - no rust issues.