Cleaning a DC motor without disassembling

[mike_mike]

Hello,
I have a question regarding the cleaning of a DC motor.
I have a mini drill (Proxxon Micromot 50) and I want to know how can I clean up the motor of this mini drill without disassembling the motor.
I already opened the case of the mini drill, I cleaned up the interior of the case and I used WD-40 to lubricate the axis that is outside of the motor.

What can I do to clean up the interior of the motor, without disassembling the rotor and the stator ?

I am not sure if there is dirt in the interior of the motor, but I just want to do a cleaning operation.

[Rick Law]

Compress air blast?

Since you said mini-drill, I assume it is small.  So, may be those hair-spray size compress air dust cleaner cans could do the job.   You can get those from stationary stores or walmart - sometimes around PC supplies since it is often associated with cleaning keyboard.

[Jwillis]

Those types don't usually require a lot lubrication ,if any, because of the bronze bearings. Get some Non lubricating Deoxit electronics cleaner and spray in around the brushes and armature.That will clear any contaminates around the brush contacts and commutator bar.Excessive oil will burn around that area and reduce he efficiency of the motor.If you wish to use a lubricant use sparingly and only a very small drop on each bearing.

[innkeeper]

there are purpose make clears for motors
crc lecta-motive is one easy to get at many auto supply places.
there's is also lectra clean by crc which some people use.
I use something i also use for brushed RC cars - T.A. Emerald Performance Plus 4
these cleaners do not attack to enamel wire coatings!
Do lube the bearings though after using it.
link to a video on how to..

[Ian.M]

WD40 is *TOTALLY* unsuitable for lubricating high speed precision motor bearings (oilite bush or ball bearings).  The non-volatile oil component of WD40 + ozone from the sparking at the brushes will sooner or later form a varnish-like gum, and if you carry on running it  the heat from friction will carbonise the gum, destroying the bearings.

After cleaning the motor with anything other than dry air, place it in a warm place for 24H to drive off any solvent residue then relubricate oilite bushings or non-sealed ball bearings with a drop or two of light machine oil (ideally spindle oil).  Turn it over by hand to distribute the oil then with the bearing end of the shaft downwards, carry on turning it over and wipe off *all* excess oil with a lint-free wipe, applied where the shaft enters the bearing.  Carry on wiping with a clean fold of the wipe till no more oil transfers to it.

[David Hess]

As Jwillis points out, it is important not to leave lubrication around the brushes which in practice means anywhere except the bearings.  Otherwise as the brushes and commutators wear, the lubrication will pick up the dust turning it into a cake which will eventually cause problems.

For bearings I have had good results with gear oil in place of spindle oil.  Motor oil works well.  I have heard good things about using heavy automatic transmission fluid.  In my experience a light oil works for cleaning a bearing but not for lubricating it.

[Ian.M]

It depends on the spindle speed.  The O.P's Proxxon Micromot 50 runs at up to 20K RPM and too heavy an oil will result in the bearings running hot, and the oil degrading rapidly due to excessive sheer. If its got oilite bushes, avoid EP gear oils, as many EP additives attack copper alloys.

[innkeeper]

the motor used inside the Proxxon Micromot 50 is a 540 style DC motor, same as used in rc cars and rc airplans. they don't use the more advanced versions that are intended to be torn down, just the cheap non-rebuildable can type... cleaning process is the same for both though..it is why I posted the instructions from an rc car youtube video. cleaning of this style of motor is well known and well documented. the RC community has been using and abusing this motor for a very long time. there are likely 100's of such cleaning and lube videos out there, and probably 100's of not 1000's of articles on this motor. .. easily googled .. google 540 motor.

cleaning and lubing will require disassembling the body to get to the motor. just no disassembly of the motor itself is necessary.

[David Cutcher CEG]

This advise from an old electric typewriter repairman. Really.
I don't know how others feel about wd40. I don't like it. It is too light, and the solvent in the spray actually dissolves other grease. More damage than helpful in the long run.
Depending on the quality, replace the bearings if they are sealed. If the insides are really dirty, brush any unsealed areas with kerosene. If the bearings are unsealed, you have can still clean with kerosene, but then have to repack the bearings.
If they are bronze bearings, and wiggly loose, they need to be replaced.
David Cutcher "Certified Evil Genius"
 

[innkeeper]

oh that reminds me.

there is a bearing at the end of the output shaft, if it is worn out it would be a good time to replace it, it is just held in by c clips. do get a high-quality high-speed replacement bearing if you are replacing it. I have a preference for Boca bearings myself, they make high speed hi load bearing for just such an application... also, you will find a setscrew on the output shaft to connect to the motor if you wanna completely disconnect the output shaft from the motor for cleaning. either way, you don't want that cleaning fluid getting into the bearing of the output shaft.

let us know how you make out.

[Zero999]

As Jwillis points out, it is important not to leave lubrication around the brushes which in practice means anywhere except the bearings.  Otherwise as the brushes and commutators wear, the lubrication will pick up the dust turning it into a cake which will eventually cause problems.

For bearings I have had good results with gear oil in place of spindle oil.  Motor oil works well.  I have heard good things about using heavy automatic transmission fluid.  In my experience a light oil works for cleaning a bearing but not for lubricating it.

Yes, the brushes are carbon which is self-lubricating. I ruined a motor before by putting lots of grease around the brushes and commutator. The result was smoke and burned brushes.

If you can just oil the bearings then good, but I'd just spray it with compressed air to clean any crap out and leave it alone. Only lubricate it, if you think it really needs it.

[Gyro]

Just curious, what do you think the motor is contaminated with?  If it's just dry dust, then I wouldn't attempt to clean it with anything wet, that will just make it clog together unless you literally flood the motor. For dry dust contamination, use compressed air - or preferably a vacuum nozzle (to avoid forcing dust into the bearings).

Hopefully none of the WD40 that you used on the rest of the drill has made its way into the motor and gummed up any contaminants.

[Ian.M]

If you can just oil the bearings then good, but I'd just spray it with compressed air to clean any crap out and leave it alone. Only lubricate it, if you think it really needs it.

Unfortunately the O.P has already used WD40 which if it has got in the front bearing, is likely to have washed out any lubricant present leaving it minimally lubricated.  IMHO it is likely to need a drop of light oil (not proprietary oil/solvent mixtures) on its front bearing to restore the lubrication washed away by the WD40, as discussed above.

[innkeeper]

SAD!!!  unfortunate the OP didn't take my advice..wd-40 is one thing you should never spray into a brushed motor.

oh well...

WD40 is known within the RC community for ruining motors.

what also happens is wd-40 burns and turns into an abrasive on the brushes, and eats the commutator.

it also ruins the brushes and it is also it is flammable, and there have been instances of motors catching on fire after people use it.

on rebuildable motors, this can be rectified if caught quick, cleaned and the brushes replaced. on a closed can there is not much you can do.. maybe try cleaning it well with some evaporative electrical cleaner like i posted and lubing the bearings... but the brushes have already been exposed to the wd-40, so the life expectancy of the motor is gonna be reduced.

 

[Zero999]

SAD!!!  unfortunate the OP didn't take my advice..wd-40 is one thing you should never spray into a brushed motor.

Unless there's another thread or private message, he'd already used the WD-40, before you advised him against it.

[Ian.M]

He said: "I used WD-40 to lubricate the axis that is outside of the motor."    As the brushes are at the other end of the motor unless he was a total numpty and drowned it in WD40, the rear bearing, commutator and brushes are probably OK.

[Jwillis]

Rebuilding larger motors I've used silicon/dielectric grease since it doesn't evaporate as much as petroleum oils/greases ,won't effect plastic parts and is far more water resistant.I wonder if it would work as well on these smaller motors .

[mike_mike]

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 ?

[mike_mike]

I put WD40 in the zone marked with the red rectangle:

[Zero999]

Rebuilding larger motors I've used silicon/dielectric grease since it doesn't evaporate as much as petroleum oils/greases ,won't effect plastic parts and is far more water resistant.I wonder if it would work as well on these smaller motors .

That sounds fine, as long as it doesn't get on the commutator or brushes.

I put WD40 in the zone marked with the red rectangle:

Yes, that's shouldn't damage the brushes. The only potential issue is it driving out any existing grease and evaporating, but that can easily be resolved by applying a drop of  light oil, as Ian suggested.

[innkeeper]

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 ?

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]

He said: "I used WD-40 to lubricate the axis that is outside of the motor."   

Ah i totally misread your comment.    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.