Basic motor cleaning tutorial
 

I thought I'd share what I've been learning about basic sewing machine motors. First off, I am self-taught, so not an expert and certainly don't know everything there is to know about small motors. If you see a glaring error, please let me know! This tutorial is simply to show the steps I've taken to clean up a couple of grimy motors and help my "rescues" run better. This is definitely maintenance for those who like to get their hands dirty!

First of all, you will need the following:

Screwdriver(s)
Cleaning supplies such as brushes, cotton balls, denatured or rubbing alcohol, paper towels, and so on
Catch all for small parts
Camera (very helpful to document your steps!)
Drill or drill press
400 and 1500 grit sandpaper (may find in automotive paint section) cut into 1/4-inch or so strips
Sewing machine oil
Patience

Remove the motor from the sewing machine. Now remove the the carbon brushes if they are accessible from the outside of your motor (some are removed from the inside and not visible outside). Look for a couple of small non-metal screws/caps. Undo these. Be careful, the carbon brushes (small solid blocks of carbon) are attached to springs. They may pop out of their holes! They may also be stuck from grime. Try to pull them out, but not too forcefully. You may have to wait until you have the rest of the motor apart and poke them out if they are "glued" in there by the grime. Set these and the caps aside.

Also, you will probably have to remove the motor pulley before taking off any of the housing for the motor. This is the place where the belt rests. Look for a small set screw holding it onto the shaft/rod sticking out of the motor. Remove and set aside.

Now, look for some screws that hold the outside housing together. Remove these and take off the parts of the housing that you can. What you are looking to eventually remove is the armature. This is a shaft/rod (the same one that the motor pulley was on) with lots of wire coils and the copper commutator at one end. You may have to remove some other parts to totally pull the armature out of the motor. Document what you remove with the camera.

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When you are able to pull out the armature, be careful--there are probably a number of small washers around the shaft. Don't lose these! They may not be obvious if your motor is really grimy and may fall off when you are cleaning.

Now that the armature is out, we need to clean it. Be careful of the small wire coils around the armature. If these are broken up or damaged, the motor is no good, and that repair is beyond this simple cleaning. Use your supplies to remove any grease, dirt, and other grime.

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Then comes the fun part involving power tools--polishing the copper commutator. This can be done with a pencil eraser, but the sandpaper works great to clean and polish the copper. Clean copper is a good conductor, and that makes your motor work better. (There is a lot of good information about how motors work on the internet if you are interested in the technical details).

First, load the armature shaft into your drill or drill press. This is probably easier with a drill press, but I don't have one. :) I don't have a bench clamp either, so I have to use my knees for this part. I also had to use rig something to keep the drill on while I use both hands to hold the sandpaper strip. Start with the 400 grit. While the armature is spinning in the drill, hold the sandpaper strip around the commutator. This will remove a lot of grime. Get it down to the shiny copper. Now, repeat this process with the 1500 grit paper strips. This really puts a nice polish on the commutator. Now that your armature is all clean, set it aside to keep from getting it dirty again!

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Now it's time to clean the rest of the motor. I try to remove as few parts as possible, so I didn't undo any of the electrical components. Remove as much grime as possible. I use cotton wrapped around a pick and dipped in alcohol to clean out the slots where the carbon brushes go. Again, be careful of the wire coils that go to the fixed magnets on the sides of the housing.

Don't forget to clean the small parts--motor pulley, washers, and the carbon brushes. You can use alcohol on the carbon to get the grime off. Again, this is a messy job. A note of caution, alcohol can hurt the finish on the outside of the motor. Be careful and use something else to clean these parts.

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On my motor, I had to replace the plug. This is about the extent of any electrical work I do, but it wasn't very difficult.

Now you just have to put it all back together. This is where the pictures come in handy! Put a tiny amount of oil on the armature shaft so that it will move freely when the armature turns. Don't get it on your nice shiny commutator though.

Last post, motor housing all together, new plug on. The final step is to plug it in and make sure it runs, then put it back on the machine. Good luck!

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Thanks for the great tutorial with lost of photos! IF I ever decide to clean a motor (I treadle most of my machines), I will follow these instructions. Thanks for posting!