Introduction: Rewinding and Renovation of the Electric Motor

Picture of Rewinding and Renovation of the Electric Motor

Hello, i am Niko, memeber of RoboSap team. In this instructables i will show you, how to rewind and renovate old electric single phase electric motor.

I bought this electric motor on garage sale. It was cheap and we known that motor burned out. I decided to buy motor and try to renovate it.

In next steps I will show you how do disassemble electric motor, remove bearings, make winding diagram, rewind motor, chose right capacitor and reassemble it with new bearings.

Rewinding is very long process. It took about two days to rewind it, replace all old parts and reassemble it.

Step 1: How Do I Know If I Have Single Phase Motor?

Picture of How Do I Know If I Have Single Phase Motor?

Single phase motor usually has two coils, main with bigger resistance (generating a pulsating magnetic field) and auxiliary with smaller resistance (gives motor a direction of rotation). There must be a capacitor on the motor. Its value is different for different electric engines (for smaller electric engines around 20 microF). 2 capacitor can be on motor, "run" capacitor (always connected, lower value capacitor) and "Start" capacitor (connected with centrifugal switch, higher value capacitor)

Picture 1: Scheme of single phase electric motor

Picture 2: Run and star capacitor

Picture 3: Wires from stator (there should be 4 wires from stator)

Step 2: Tools

Rewinding and disassembling motor is very time consuming work, if you don´t have professional equipment. You will need following tools:

- Basic tools (screwdrivers, hammers, wrenches...)

- Pulleys for bearings

- Chisels, to cut off old winding

- Butane torch (or other heating device)

Special Material:

- Copper wire

- Isolate paper

- Stator lacing thread

- Spray Lubricant (WD-40 or similar)

- Motor lacquer

Step 3: Disassembling Motor

Picture of Disassembling Motor

Take few pictures of motor, and Remove the fan protective cover. Usually the cover is not screwed with screws on housing but it's just plugged on housing.

Put all removed parts of motor in one box so you don't lose them.

Step 4: Disassembling Motor

Picture of Disassembling Motor

Gently heat up motor fan and remove it. Be careful you don't break it, it should go very smooth. You can help yourself detaching it with two big screwdrivers.

As you see on picture our motor fan is broken and we need new one.

After detaching motor fan remove clamp from axis.

Step 5: Disassembling Motor

Picture of Disassembling Motor

Mark the position of individual covers, on the side of covers (usually we put numbers 1, 2, 3 on side of covers, so we will know to assemble it).

Unscrew the screws securing the cover (picture 2). Remove the cover of motor and put it in the box with other parts.

Step 6: Disassembling Motor

Picture of Disassembling Motor

When I removed cover my expectations came true. One of the motors winding burned out (black colour and smell of burned lacquer).

I find out that bearings are broken too (when you spin it, it creates loud sound).

Step 7: Disassembling Motor

Picture of Disassembling Motor

Unscrew the screws securing the front cover (as you'we done 2 steps before). Gently remove the front cover with rotor out of main housing and put it in the box with other parts.

Step 8: Disassembling Motor

Picture of Disassembling Motor

Unscrew the screws securing the top cover. Remove the top cover and sealing and put it in the box with other parts.

Take few pictures of electrical installation and remove all the wires and electrical clips. Remove capacitor, if you have one on motor (our was cut off).

Step 9: Motors Inscription Board

Picture of Motors Inscription Board

Try to write down all information from inscription board. It is located on motors housing. There are some useful information on it (voltage, current, number of turns per minute, capacitor...).

Step 10: Winding Diagram

Picture of Winding Diagram

In next steps we are going to make winding diagram. If you have one, you cant skip titles "Winding diagram"

What is winding diagram?

Winding diagram is diagram which helps you rewind motor. It show how stator coils are connected with each other.

Step 11: Winding Diagram

Picture of Winding Diagram

Count number of slots (gaps in stator, look at pictures).

I counted 24 gaps.

Step 12: Winding Diagram

Picture of Winding Diagram

Open your best drawing program and draw 1 square for each slot connecting each other.

Step 13: Winding Diagram

Picture of Winding Diagram

Each of coil is placed in 2 slots. Draw coils from your stator to your winding diagram.

Do same for all coils. There cant be 2 coils in one gap (if you have Single-layer winding). All of gaps needs to be full.

Step 14: Winding Diagram

Picture of Winding Diagram

Mark output coil wires (wires that were connected on electrical clips).

Step 15: Winding Diagram

Picture of Winding Diagram

Heat up old winding, so you burn out old lacquer, but be careful, you must not damage copper wires.

When you can clearly see hot coils are connected, chose one of the output wire and draw path of it with arrows.

Step 16: Winding Diagram

Picture of Winding Diagram

Make same thing for second pair of output wires.

I found same winding in the book (it is just rotated for 180°).

You can draw gaps in circle and mark x (wire in) and . (wire out). Now you are able to draw path of magnetic field (picture 3).

Step 17: Winding Diagram

Picture of Winding Diagram

Cut wires of different coils and count them and measure their diameter. Write number of wires in each coil in winding diagram.

Now your winding diagram is complete!

Step 18: Winding Diagram (Skip This If You Have One Wire Coil)

Picture of Winding Diagram (Skip This If You Have One Wire Coil)

Be careful. If your coil is made out of 2 parallel wires, you can replace them with one wire. Measure diameter of 1 wire. Calculate plate of 1 wire and multiply with 2. Now calculate 1 wire from your plate. (New wire must have same plate as old 2 wires together).

Step 19: Cut of Winding

Picture of Cut of Winding

Use hammer and Chisels to cut off old winding. Try not to damage stator lamellas. You can continue when you cut the old winding on one site (Picture 5).

Step 20: Pull Out Winding

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Heat up other side of old winding and pull it out using crowbar. Do these for all coils.

Step 21: Clean Gaps

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Until stator is hot, clean gaps with screwdriver or iron stick, but don't damage stators lamellas.

Step 22: Remove Pulley

Picture of Remove Pulley

If you have one, remove screw or safety metal stick, and then pull pulley with puller from axis. If you need, heat pulley (not axis!!!!) with butan torch.

Step 23: Remove Front Cover

Picture of Remove Front Cover

Put cover on wood, so rotor doesn't touching the bottom. Put piece of wood on axis of rotor and hit it with hammer until rotor separates from cover.

Step 24: Removal of Bearings

Picture of Removal of Bearings

Use puller to remove bearings on both sides. You must not damage the axis of rotor.

Step 25: Clean Housing of Motor

Picture of Clean Housing of Motor

Motor was covered with concrete so we decided to sandblast it.

Step 26: After Sandblasting

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Don't sandblast or scratch stator lamellas too much, they are made of iron which can rust.

Step 27: Twisting Edges of Insulating Paper

Picture of Twisting Edges of Insulating Paper

Put isolate paper on table, and place ruler on it, so you get about 4mm gap in witch you will insert isolate paper and then twist it.

Step 28: Insert Isolate Paper in Stator

Picture of Insert Isolate Paper in Stator

Mesure lenght of gap, and add about 16mm (depends of how you will twist paper). Cut it and twist it as I have done on pictures. Use screwdriver to bend it and insert it in gap. It should fit perfectly so you cant pull it out. Picture 11, front side of motor, and picture 12, back side of motor.

Step 29: Insert Isolate Paper in Stator

Picture of Insert Isolate Paper in Stator

Do same thing for all gaps

Step 30: Coil Winding

Picture of Coil Winding

Make model of coil with one wire leaving a little bit more space. Put it on "Winder" to get distance. Put model off, and set winder to right distance, then start winding coil (you written numbers of wires in coils before). You can use same distance for winder for same coils.

You can make winder at home. I redraw my in fusion 360 so you are able to print it and make one for yourself.

Step 31: Place Coils in Stator

Picture of Place Coils in Stator

Careful place coils in stator. This can take a long time to do. Be gently so you don't damage wires lacquer. Rotate coils so their end wires will come out on the side, where is the hole from stator to electrical clips.

Step 32: Wire Coils With Winding Diagram

Picture of Wire Coils With Winding Diagram

Connect coils according to the winding diagram. Remove isolation, then solder copper wires and isolate them with heat shrinks. Connect normal wires with end coil wires, and isolate them with heat shrink (picture 9). Wire them to electrical clips.

Step 33: Bind the Coils

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Bind the coils with the stator lacing thread. Sew stator lancing thread around coils, as you can see on pictures.

Step 34: Bind the Coils

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Do the same thing on other side of motor.

Step 35: Varnishing the Motor

Picture of Varnishing the Motor
1. Heat up cooking oven to 100 °C. Put motor in it.
2. When motor heats up, spills lacquer on motors coils as you see on pictures

3. Turn motor around and do the same

4. You can reuse old lacquer.

5. Put motor in hot oven, and cook it for about 4 hours

6. Take motor out and clean edge (so cover will fit perfectly).

Step 36: Bearings

Picture of Bearings

You can find appropriate bearing, by measuring old bearings diameters. Then you can find new ones in this catalog.

There are also small numbers on edge of bearings, and you can read them (for example 6302).

Step 37: Assemblying Bearings

Picture of Assemblying Bearings

Grease the axle of rotor with lubricant and mount bearings on axle.

Step 38:

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Grease the bearing bed with lubricant, on both covers. Place first cover on rotor (don't forget for spring washer). Then place stator over rotor on first cover, and screw it (don't forget to glue screws). After that place second cover on top of the stator and screw it (glue screws).

Step 39: Motor Fan

Picture of Motor Fan

When i cleaned fan i realise, that it is cracked. I made aluminium ring on lathe and glue it on fan.

Put clamp on rotors axle. Mount motors fan on rotor (you can heat it with an industrial fan, but dont overheat it because it becomes really soft and can change shape). If you have cracked fan, you can buy new one, they are cheap. I just wanted to show you that you can repair it.

Step 40: Fans Protective Cover

Picture of Fans Protective Cover

I sandblasted it and repaired cracks, with soldering iron and iron mesh, witch i heated in plastic. I painted it in black and install it on motor (no screws needed).

Step 41: Capacitor

Picture of Capacitor

Mount capacitor on motor with zip ties (drill holes in housing as i have done on pictures). If you don't have capacitor there is right value on motors inscription label on housing (for my motor is 20 microF). Lead wires to connection box of motor.

Step 42: Electrical Clips

Picture of Electrical Clips

Lead power cable into connection box and tighten it, so you can't pull it out. wire clips as i draw on picture 3.

My seal of cover was damaged, so i made new one from old rubber sponge. Screw cover on motor.

Step 43: Mounting Pulley

Picture of Mounting Pulley

Grease the rotors axle with lubricant, and mount on pulley.

Step 44: Test

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Plug in the motor and measure its current (it is about 1A for my motor). If it runs smooth than you finished.

Step 45: Conclusion

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Rewinding the electric motor takes a lot of time, as specially if you are doing it for first time. But when you see finished product, wasted time pays off.

If you have any problem, write it in comments bellow and i will try to solve it.


WARNA (author)2017-11-27



jeanniel1 (author)2017-09-10

WHOA! Such a lot of work, but you're right, it pays off in the end. Really good work on the instructable. Thanks a bunch for posting this!

bgreen3 (author)2017-09-09

This is a great guide for rebuilding motors.

OmarJ3 (author)2017-09-09

Hi robo, as akatengu mentioned, this brings back memories from 70 years ago of watching my father and brother rebuilding AC motors in our home workshop. During and post WW2, this was a good business, as industry concentrated on war supply. One thing mentioned, as can be seen in your before photos, are the insulating paper tubes in the slots. My father made a kind of jig with two small wheels on a crankshaft, which would indent the paper with parallel lines for folding. After the coils were in place, he inserted a thin wooden stick at the top of the slot to snug it down. finally, he brushed on a GE product called "Glyptal", a kind of thick red paint, and "cooked" it. They also rewound armatures, etc.

michaelmacnz (author)2017-09-08

Well done... You have unraveled the mystery of single phase motor/s for me.

ba38 (author)2017-09-08

Hi all

Nice work !

Changing the wiring diagram, you can easily get a 3 phases motor with the possibility to feed him with an inverter and gain bidirectionnal rotation and variable speed as the number of slots is a multiple of 3 (here 24).

Thank you for this work.

cavalier19 (author)2017-09-08

Amazing instructable. Very well explained. One of the very best

avayan (author)2017-09-08

The amount of valuable information in this Instructable is off the chart! Thanks for putting it together. I am hoping I am never in need of having to undertake such a laborious task, but just to see how it could be done is so useful and inspiring. And your results are practically a work of art! Kudos to you, sir!

cirano (author)2017-09-08

Good, clear instructions. Thank you!

dukmata (author)2017-09-08

an excellent instructables

Stewart78Z1R (author)2017-09-07

Great job, very informative. I did not see any mention of what you intend to use the motor for, hopefully something productive.

cbrown5 (author)2017-09-07

Beautifully written and explained. I never knew how this was done but learned quite a bit. Thank you for contributing this!

Gofish (author)2017-09-07

Hello Niko,

Thank you for such an excellent instructable, love the winder, I think your good Karma must be off the scale.

Paul Morrison (author)2017-09-07

Very Very neat pro job - thanks for sharing !

JankoJ (author)2017-09-07

According the way those winding's are connected with the capacitor, you can use that electric motor as self-actuated generator! Just clutch the axle to some engine or to another electric motor with same or more output power, set the RPM to it's nominal and you'll get the output of electric power that is 60% more than basic! For example, if your motor is 1kW, as self-actuated generator he will give you 1,6 kW of electric power!

HowardH27 (author)2017-09-07

Excellent instructable! How do you determine what size/gauge wire to use for the windings?

ElegantAndrogyne (author)2017-09-07

A pro's job, and the motor looks good as new. The only thing I can criticize is a lack of gasket/strain relief on the capacitor's cable. Everything besides that looks splendid.

akatengu (author)2017-09-07

Beautifully & skillfully done, AbrahamT5! Excellent tutorial and instructions! Best I have ever seen on Instructables site. In 1964, I was fortunate to become the apprentice to a Dane, Ralph Eckstrom, who taught me to rewind AC and universal motors. Although I rewound several hundred motors in the early 60's, I haven't done it for 50 years. Reading your instructable took me right back. Your instructable is like a log book of what I was taught. (Although shown in your pictures, you didn't mention the insertion of a paper "slot cap" strip that closes each slot and retains the winding before binding.) I'm happy to see this skill still being passed down. There are very few shops around still doing this work. Our throw-away society would do well to further encourage such renovation. With copper at >$2.50/pound, you could even partially recoup some expense by recycling those old windings, eh? Many thanks!

ajayt7 (author)2017-09-07

What a detailed presentation, very lucid! Thank you

elpayo (author)2017-09-07

A lot of work, really. Very best intructable I see.

Thanks a lot

sitearm (author)2017-09-07

"Put motor in hot oven, and cook it for about 4 hours" love it! : )

relbatto (author)2017-09-07

This is a truly great job of explaining a complex concept. here in oklahoma, many large electric motors are used in oil and gas production, they fail from thunderstorm strikes, and have to be re built. this process was always a mystery to me and you have done a superb job of imparting the method of re building them. By all means keep these instructables coming on 3 phase motors and do them for 12 volt starters, and generators , and especially for aviation units. this is almost lost knowledge, as the old shops have mostly closed and disappeared.

ashraf hussien (author)2017-09-07

great effort sir, may I add great site

steveastrouk (author)2017-09-07

A very brave project to start, and an amazing result when finished. People who will rewind these small motors are getting very hard to find, so this is a great Instructable, and I've favourited it.

Neowizard (author)2017-09-07

Recently, I found a 2HP 3phase motor with broken field winding. I wanted to find out how to rewire it for single phase. This will definitely come in handy. Thanks!

hamthis (author)2017-07-19

Great Post I have been looking for information like this for some time. Very well thought out. I have a motor that I am trying to rewire. not sure if it is shot and needs a total rebuild. I have a couple questions. My Motor is a 32 channel stator it has thin wires around the interior with two wires coming from these windings (J,C) and it has thicker wires around the perimeter with four wires coming from these windings(1,2,3,4) The motor has a Capacitor with a centripetal clutch. I am pretty sure it is 220 volt. I have continuity on these wires (J-C) and (1-4) and (2-3) I am trying to find how to wire this to the 220 with the start capacitor. Do you have any info on this?

robosap (author)hamthis2017-07-21

Hello, i first time see this type of coiling. Why is this motor used for?

hamthis (author)robosap2017-07-21

It is for a 24" disc sanding machine like the one shown below it spins a 24" disc that weighs about 40 lbs. It just seemed odd to me that there would be continuity in pairs on the 6 wires coming from the stator. One thing to note this is a reversible motor built to spin both directions.

acheide (author)2017-07-16

Most nicely done with clear instructions. Thanks.

robosap (author)acheide2017-07-16

Thank you!

AbrahamT5 (author)2017-07-16

what are the two Winder.f3d downloads, how do I open them?

robosap (author)AbrahamT52017-07-16

There are two files of Winder, .stl for 3d printing, and .f3d which can be opened and modified in Fusion 360 (CAD program). If you print two pieces of Winder, you can make tool for winding coils (Step 30: Coil Winding, white pieces).


AbrahamT5 (author)2017-07-16

What a great contribution ! Very well written with wonderful pictures. Thank you for the effort behind it, which would have been quite long. There are a few spelling mistakes. They can be corrected if you revise this, otherwise leave them. Waiting for 3 phase instructable

robosap (author)AbrahamT52017-07-16

Thank you! I am going to correct spelling mistakes this week.

tytower (author)2017-07-11

Think you might have a go at my 43KVA 3 phase now . I could use a hand!

robosap (author)tytower2017-07-11

Well, the principle of winding is same for small and big motor. Bigger motor has bigger gaps so you can easier put coils in gaps. If you want i can make 1 more instructable about rewinding 3 phase motor.

tytower (author)robosap2017-07-13

Yes please . Its a task I have always had difficulty following

bwatt1 (author)2017-07-13

wow really cool. it will last another 40years for sure.

robosap (author)bwatt12017-07-13

Thank you!

cobourgdave (author)2017-07-12

What a great instructable! Well illustrated, well written, and one GIGANTIC effort on your part. I see in the comments that this is your first motor rewind, which serves to emphasize your courage. I don't intend to try this, but it reminds me of electrical class in high school in the dark ages of the 50's...Well done sir!!

robosap (author)cobourgdave2017-07-12

Thank you!

gareth.hammond.12 (author)2017-07-12

Wow that looks very intense renovation. After this may need to consider just buying a new one.

Thank you!

gm280 (author)2017-07-11

That is the most step by step precise motor rebuild I have ever read. Bravo sir, bravo. I get the feeling you have done this before, probably many times before. A true gutsy rebuild indeed. I enjoy rebuilding things, but I am not so sure I would have had such success on my rebuild. Where did you buy the lacquered winding wire?

robosap (author)gm2802017-07-11

Thank you! This is my first time rewinding motor. I just saw process of rewinding in factory, but they had professional machines, for making coils and cooking lacquer. They were rewinding much bigger motors that mine, but as i said before procedure is same. I bought used wire few years ago over internet.

BeachsideHank (author)2017-07-10

Absolutely incredible, if this is the first time for you doing a motor rewind, it is beyond belief, even seasoned electricians would shy away from such a task but you have all the details done right. I can't overstate my respect and admiration for this accomplishment. ☺

robosap (author)BeachsideHank2017-07-10

Thank you!

belfastrab (author)2017-07-10

Wow that is a crazy amount of work and that's just the detail you put into the Instructable! I always wondered how they were rewound now I know. Superb job that must have taken a serious chunk of time. Crazy to think only a few decades ago every single big town and city across the world would have a shop that specialized in this and now people just throw away and buy new. I couldn't even tell you if there is a single person doing this in my whole country anymore let alone city.

belfastrab (author)belfastrab2017-07-10

Forgot to add you get my well deserved vote in both competitions you are in!

robosap (author)belfastrab2017-07-10

Thank you!

About This Instructable




Bio: We are group of young engineers. We like to build stuff.
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