Electronics > Beginners

Cleaning a DC motor without disassembling

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innkeeper:

--- Quote from: mike_mike on May 02, 2019, 09:47:26 am ---Thank you for all your advices.
I used WD40 before posting this thread.
I used WD40 only at the end of the motor, where the axis is out of the motor. I hope that WD40 did not get in the interior of the motor.
I cleaned using compressed air spray the interior and the exterior of the motor and before using compressed air I cleaned all the WD40 using a paper towel.
After cleaning, i put a drop of oil at the axis of the motor.
Are there any other things that I should do ?

--- End quote ---
If your goal was to just blow out the old carbon brush dust, then air is fine. However if you were doing it because you had some arcing, then likely you need to use the motor cleaning spray to loosen up and remove the buildup between the commutators.

For oil on the end bearings/bushings., many people swear by 3 in 1 oil or 3 in 1 electric motor oil which is 20W.  Some like non-detergant synthetic 30W which is harder to find, but honestly better (sold for use in small gas engines).  I use 3-in-1 myself which is a 20W oil.  in general, motors are lubricated from the factory with 20W or 30W oils. DO NOT USE OILS WITH DETERGENTS!

NOTE on Detergent Oils:
The core issue is the detergent tries to clean and carry away contaminants but because there is no oil flow or filtering like in a petrol engine, the contaminants have no place to go so they end up gumming things up and causing more wear.  Its good practice not to use detergent oils in any system that doesn't contain a filter for that reason.  it is not good for any general lubrication like bearings and bushings in an electric motor.

Little note on WD-40:
don't get me wrong ... I love WD40...its an awesome for protection against moisture, great for cleaning things and freeing up parts, etc, I keep my can sitting inside my roll of duct tape  :) ... WD40 is not a good long term solution for lubricating the ends of the motor, it is really a poor lubricant for high-speed parts, though it will clean out the old lubricant well.  Few observations on WD-40 made by many is that it contains some form of carrier similar to kerosene (which is not a lubricant at all) and some type of lubricant that some believe to be vegetable based, what happens is when kerosene type liquid evaporates it leaves behind a gooey substance which is the remaining lubricant. people have observed white and/ or green gooey residue on things that have been lubricated with wd-40 and the kerosene-like carrier has evaporated.  Don't get me wrong, the kerosene-like carrier doesn't seem to evaporate fast, probably more quickly under heat though.  personly I have observed the mess from WD-40 where someone sprayed switches years ago, and now there is a  gooey mess that needs cleaning up.

Hope this is helpful information.

innkeeper:

--- Quote from: Ian.M on May 02, 2019, 08:15:49 am ---He said: "I used WD-40 to lubricate the axis that is outside of the motor."   

--- End quote ---

Ah i totally misread your comment.  |O  PHEW! he didn't mess up the motor.

innkeeper:
locations to lubricate marked in yellow

dansurplusman:
Speaking as an old in general, but only been fixing them for about 15 years, typewriter guy:  This thread seems to be about high speed lightweight motors such as for hand tools, and many who posted say WD40 can ruin a tool by gumming things up in various ways.  In a low speed, stepper motor type, environment, that may not be an issue.  Years ago I learned from a typewriter repair person (who has been fixing Wheelwriters for probably over 40 years by now) that the small motors used in IBM / Lexmark Wheelwriter typewriters (the last kind of typewriter IBM ever made), especially the one that moves the platform containing the parts that actually put characters onto paper, to move that platform back and forth (and probably to roll the "platen roller" up and down, to reposition the typing paper in the machine, can be revived by giving them a good dose of WD40.  As in, I suspect you could literally soak one of those small motors  (about the size of a 1" thick slice off of a 3" diameter salami) in a wide mouth jar of the stuff, though I just use a spray can.  I didn't believe it would work, but I've revived many of those motors over the past 15 years or so on Wheelwriters that I am working on to sell on eBay -- probably over 50 with the problems that result from a "Sticky" motor that either won't move that platform at all, or gets stuck trying to do a "carriage return" function and only goes part way and "jams".  Because I've had the same seller ID there for probably the entire time I've fixed and sold Wheelwriters, and tend to use very similar language in all of my Wheelwriter ebay listings for almost that entire time, I'm sure someone would have found a way to contact me and complained and/or asked for help by now if the "fix" was short-lived for them.  So maybe, when it comes to a small low speed electric motor, that isn't running all the time and might only spin a fraction of a turn at a time with at least a fraction of a second between each activation, the problems reported here about WD40 in higher speed, longer duration running, electric motors just don't happen.

Jwillis:
I just repair my furnace fan motor today. The bearings were dried right out and loading the motor down. I used high temp silicon automotive brake grease to repack the bearings. Works like a charm.

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