I need help with rewinding my angle grinder motor.

Thread Starter

fredy mredy

Joined Jul 5, 2019
4
Hello, i have this angle grinder in my garage for few years and one of the stator coils is broken, so i took it off in hope that i can count it and rewind it but sadly the winding is glued so tight that i just damaged more the winding, so is there a way to calculate how many turns i need in my coil so i can rewind it?
Images from the stator, the coil i took it off and some info about the angle grinder:
https://imgur.com/a/t0fqi3Q
 

SLK001

Joined Nov 29, 2011
1,504
Don't waste your time. Go down to Harbor Freight and pick up an orange angle grinder or one of their Hercules models.
 

MaxHeadRoom

Joined Jul 18, 2013
19,029
I agree it may not be worth it, but to count the turns we used to first use a cold chisel to shear off one end of the windings in the stator, then drive the winding out and count the turns.
You would also measure the inside dimensions/diameter needed in order to make up a winding former/bobbin.
Max.
 

MisterBill2

Joined Jan 23, 2018
3,869
You can measure the wire diameter and count the number of turns in the winding and then create a new winding, with the only serious challenge being getting the polarity correct. THAT MATTERS A LOT.
And please consider that the $9.95 angle grinder at harbor freight is rather lacking in quality of the metal both in the body and in the gears. So if you only need to use it once and only for a few minutes that may be fine. I try to avoid purchasing single use tools.
 

shortbus

Joined Sep 30, 2009
6,979
And please consider that the $9.95 angle grinder at harbor freight is rather lacking in quality of the metal both in the body and in the gears. So if you only need to use it once and only for a few minutes that may be fine. I try to avoid purchasing single use tools.
Not so. I have one that I bought to grind some stone using a dry diamond wheel still running strong, after 3 years of other use on metal/welds. Repeating things you see online and not do yourself is not a good thing.
 

SLK001

Joined Nov 29, 2011
1,504
...And please consider that the $9.95 angle grinder at harbor freight is rather lacking in quality of the metal both in the body and in the gears. So if you only need to use it once and only for a few minutes that may be fine. I try to avoid purchasing single use tools.
That's why I recommended the orange or the Hercules models. The $10 models (the "blue" models) are basically junk.
 

narkeleptk

Joined Mar 11, 2019
372
The good thing about a $10 tool is you can use it and abuse it and not feel bad. Believe it or not many of the smaller hand tools at HF hold up pretty well and when they don't you can just replace it for another $10. Don't get me wrong, I have and mostly use high end tools personally. They give the best impression to clients but I also have plenty of low end ones as well. Not much difference if you ask me. They both do what they are intended to do.
 

MisterBill2

Joined Jan 23, 2018
3,869
Not so. I have one that I bought to grind some stone using a dry diamond wheel still running strong, after 3 years of other use on metal/welds. Repeating things you see online and not do yourself is not a good thing.
I was commenting on the one that I have. "Your results may differ." WAY to much play in the drive gears.
 

Thread Starter

fredy mredy

Joined Jul 5, 2019
4
You can measure the wire diameter and count the number of turns in the winding and then create a new winding, with the only serious challenge being getting the polarity correct. THAT MATTERS A LOT.
And please consider that the $9.95 angle grinder at harbor freight is rather lacking in quality of the metal both in the body and in the gears. So if you only need to use it once and only for a few minutes that may be fine. I try to avoid purchasing single use tools.
Thanks for the info, i have much better angle grinders, one small one big both of them are bosch. The one that is broken i got it from a friend for free and it was sitting in my garage. I want to rewind it because i have all the materials but im unable to count the turns because the coil is glued so tight that i cantcount it.
 

MisterBill2

Joined Jan 23, 2018
3,869
I know it does not worth but i have wire that i dont need so i can rewind it.
The several challenges with rewinding are getting the direction right, keeping the wires from being damaged while winding, keeping the windings from getting tangled with the rotor,, and getting the right number of turns. Then, after it is all in place, you do need to varnish it wit something to hold the turns in place. That can take some time. Nothing really hard, but rather tedious and time consuming.
 

MaxHeadRoom

Joined Jul 18, 2013
19,029
It should be simple to ID the ends of the coil for correct (re)-termination. Just observe the winding rotation direction.
If building a coil bobbin to rewind (recommended), then there should be no damage to the new winding, the varnish is very hard.
One source is MG Chemicals for small qty of winding varnish.
A Universal motor is generally easier than the Induction type.
Max.
 
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Thread Starter

fredy mredy

Joined Jul 5, 2019
4
It should be simple to ID the ends of the coil for correct (re)-termination. Just observe the winding rotation direction.
If building a coil bobbin to rewind (recommended), then there should be no damage to the new winding, the varnish is very hard.
One source is MG Chemicals for small qty of winding varnish.
A Universal motor is generally easier than the Induction type.
Max.
Thanks max for replying, i got the direction right, next week when i have a some free time ill cut the old winding in half where is in good condition ( where are no wires broken) and i will count the numbers of turns, any tips for this?
 

MaxHeadRoom

Joined Jul 18, 2013
19,029
Thanks max for replying, i got the direction right, next week when i have a some free time ill cut the old winding in half where is in good condition ( where are no wires broken) and i will count the numbers of turns, any tips for this?
No easy way that I can think of, just old fashioned patience!;)
Max.
 

Janis59

Joined Aug 21, 2017
767
I am living in country where people rarely are throwing out the things while it is possible to repair it. But not things containing a collector motor. First, the winding must be damn accurate balanced, otherhow tonns of centifugal force will destroy it at minutes of work. Next, even after well made balancing the wire may move, thus the motor will collapse again, if only to not fix every wire with good glue, for what the special lack is most spread alternative, or epoxydes, but normal full immersion is not good enough, You ought to organize the vaccuum impregnation. Thus, for the aim of saving device what new cost in shop 10 USD or best case 50 USD, You shall use a materials for 100 USD, three days, and will get the success probability 1%. I have done it many years ago, and in good specialized repair shop, after 3rd fail I threw it out. Average after "repair" it worked exactly one day.
 

MaxHeadRoom

Joined Jul 18, 2013
19,029
while it is possible to repair it. But not things containing a collector motor. First, the winding must be damn accurate balanced, otherhow tonns of centifugal force will destroy it at minutes of work. .
The OP states Stator!
Field coil of a Universal motor. Does not rotate!
Max.
 
I just spent the extra $20 odd $$'s and got a DeWalt!
Max.
I have a DeWalt angle grinder. It wasn't variable speed.

Why do they make the cases too small? My Bosch jigsaw case has the same problem.

Cases never have room for it's "tail" (the cord strain relief). I can barely put in a wrench (not the standard wrench).

It's primary use is with a wire brush to remove the grass/weeds/trees between the cement sidewalk/driveway joints after killing them.

I have a harbor freight reciprocating saw for pruning, an occasional cut of galvanized drain pipe and with an SS blade butchering a piece of meat.
 

MaxHeadRoom

Joined Jul 18, 2013
19,029
My inventory of power saws (and cut off) is:
Craftsman Radial arms saw.
Sawsall reciprocating saw.
Mastercraft Jig Saw.
DeWalt Angle grinder.
Pneumatic reciprocating saw.
Portable Hand saw.
Electric Chain saw with telescoping extension pole.
The only one kept in the case is the Sawsall.;)
Max.
 
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