How To Re-Wire A Potted Motor, Purpose 17: Cleaning The Commutator

Now that our potted motor has been rewired in addition to is partially dorsum together, nosotros ask to set the armature dorsum inside. But outset nosotros ought to build clean the business office of the armature called the commutator. The commutator is the serial of copper bars arrayed inward a ring. They are what the motor brushes brand contact with, in addition to they ask to live smooth in addition to build clean thus that electricity tin live transmitted betwixt commutator in addition to brush.

The Singer manuals all nation to build clean your commutator amongst nada to a greater extent than than a pencil eraser, but inward do that’s never worked for me. Perhaps it was a valid create 5 or x years into the life of the machines, but some of mine are from the 1930s in addition to require to a greater extent than aggressive cleaning techniques involving a ability drill in addition to some sandpaper. The best thing to purpose is really a safe honing stick, but equally I'm guessing close of you lot don't receive got access to those, I'll present you lot how to produce this amongst sandpaper you lot tin notice inward whatever hardware store.

But, past times all means, outset plough over the pencil eraser a shot; if yours come upward build clean amongst an eraser, you lot tin relieve yourself some problem in addition to skip the residual of this entry. (You’ll know it’s clean, past times the way, when the surface looks similar a build clean penny. It doesn’t receive got to live completely sparkling, but at that spot ought non live whatever night spots.)

First off, here’s a Worst-Case Scenario armature. (Actually I should upgrade this to a Bad-Case Scenario armature--for a genuinely Worst-Case one, banking firm friction match out this ane on the MSMO blog.) This is from a potted motor where soul patently squirted stone oil straight downwards the brush tubes. The commutator is covered inward black:

By using a Q-tip in addition to rubbing alcohol, I’m able to teach it to the Earth seen inward the photograph below. While doing it I receive got to live careful to purpose the smallest amount of alcohol possible, blotting the Q-Tips well, thus that no excess fluid runs onto the wiring insulation, where it is jump to produce some damage. Then I’m fix for the side past times side step.

This is what your normal dingy armature looks like, inward a machine where soul has non mistakenly injected stone oil into it. If it alone looks similar this, you lot tin skip the rubbing alcohol pace in addition to start from here.

What you lot desire to produce is teach 2 dissimilar grits of wet/dry sandpaper, available at whatever hardware store: 600 grit for the initial cleaning, in addition to 1500 grit for the end polish.

Cut a strip off of each sheet, preferably off of the long side, that is 3/8” wide.

Then insert the shaft of your armature into a ability drill, making certain the chuck is thus properly tightened, for safety’s sake.

WARNING: If you lot produce non receive got sense amongst ability tools, PLEASE enquire soul to a greater extent than experienced to produce this for you. It should live a uncomplicated thing for them to follow along amongst these instructions. If you lot receive got never used a drill earlier in addition to produce non properly tighten the chuck, you lot are setting the grounds for a real nasty accident. So delight hollo upward twice earlier doing this. The armature shaft must live securely chucked into the drill, amongst null adventure it volition come upward free.

The side past times side pace is to purpose the 600 grit sandpaper. What to produce is close easily illustrated inward video:

You’ll banker's complaint that inward the video, my fingers are quite roughly the drill. That is because I’ve done this a divulge of times in addition to am completely comfortable amongst it. If you've never done this before, you lot may desire to concur the sandpaper much farther down, equally inward the photograph below. Also banker's complaint that you lot must pinch the sandpaper together betwixt your fingers quite tightly.

Another tip is, you lot don’t receive got to clitoris the sandpaper downwards amongst a lot of force; you’re just trying to exert plenty clitoris per unit of measurement area that the sandpaper is rubbing the commutator, non grinding it into bits. We’re just trying to wipe the commutator clean, non really sand it. The copper comes off quite easily--too easily, equally you lot tin encounter past times the copper dust inward the photograph below--and nosotros desire to live careful to take equally piffling of it equally possible.

After our initial cleaning amongst the 600 grit sandpaper, nosotros take the armature from the drill. Next nosotros purpose a plastic implement--I’m using a clay-shaping tool here, but you lot could in all likelihood purpose a inexpensive plastic knife--to scrape out the night gaps betwixt the copper bars on the commutator. This procedure is called “undercutting the mica.” Use caution thus equally non to avoid scratching the copper plates, snuff it on your utensil inward the gaps.

Here you lot tin encounter some of the dark crap that comes out of the gaps:

I vacuum those away amongst a brush attachment on my family vacuum.

Then I teach dorsum to the drill, this fourth dimension polishing it amongst the 1500 grit sandpaper. The procedure is just the same equally inward the video above.

Please don't set your fingers this roughly the drill unless you've done this a divulge of times.

Finally I hitting it in ane lawsuit again amongst the vacuum, in addition to straight off we’re proficient to go. It's equally build clean equally a newish penny, non perfectly shiny, but proficient plenty to cleanly transmit electricity.