I have an old Milwaukee Hole Hawg. The coil burned up so I'm rewinding it by hand. As far as I can tell it was 18 gauge wire, but all I have handy is 19 gauge. Can I do a few extra wraps at each point to increase the length which will of course increase the resistance and reduce current flow? Or is there a chance that will mess up seriously with some other function?

 

I have an old Milwaukee Hole Hawg. The coil burned up so I'm rewinding it by hand. As far as I can tell it was 18 gauge wire, but all I have handy is 19 gauge. Can I do a few extra wraps at each point to increase the length which will of course increase the resistance and reduce current flow? Or is there a chance that will mess up seriously with some other function?

19 AWG wire is smaller in diameter than 18 AWG wire. Hence going to 19 AWG is going to increase the DC resistance, not decrease it. But the DC resistance is not as important as the inductance. The DC resistance is very low and a slight increase is not going to make much difference. You want to wind the same number of turns as what was there originally.

 

What type of motor is it?
Is this the stator?
I believe they have universal motors , if so what are you rewinding?

 

19 AWG wire is smaller in diameter than 18 AWG wire. Hence going to 19 AWG is going to increase the DC resistance, not decrease it. But the DC resistance is not as important as the inductance. The DC resistance is very low and a slight increase is not going to make much difference. You want to wind the same number of turns as what was there originally.

Yes, that's why I was suggesting extra turns, increase resistance, reduce current. But if the extra turns will mess with it then I'll definitely not do extra turns and I'll just get thicker wire to improve the ampacity so it won't overheat next time.

 

What type of motor is it?
Is this the stator?
I believe they have universal motors , if so what are you rewinding?

It's a Milwaukee Hole Hawg, a $330 tool. Brushless motor; the stator windings are what burned up. If I can fix it by rewinding it I'm gonna do that and save the $330 vs buying a new one.

 

Let's say I have a brushless motor wound with 18 gauge wire. If I need to replace the winding, and I use the same number of turns but instead I use two parallel 24 gauge wires (which will result and slightly greater cross-sectional area), will it have a fairly similar properties? Or will it be quite different? If it's different, how so?

 

It should work, as long as there is enough space to house it.
Observe correct winding direction of each pole.

 

The very first question I have is :Why did the motor burn up?? Certainly there was a reason. Ifyou rewind the motor without fixing the reason that the motor burned up, probably your rewound motor will also burn up.

Aside from that, you may be able to purchase just the portion of the motor that burned up. THAT is because those MILWAUKEE products ARE WORTH REPAIRING. Andthe coils portion of the motor will cost quite a bit less. BUT you will need to contact the manufacturer.

 

two #24 wires have same cross section as single #18 so it would be better than single #19.

 

The very first question I have is :Why did the motor burn up?? Certainly there was a reason. Ifyou rewind the motor without fixing the reason that the motor burned up, probably your rewound motor will also burn up.

Aside from that, you may be able to purchase just the portion of the motor that burned up. THAT is because those MILWAUKEE products ARE WORTH REPAIRING. Andthe coils portion of the motor will cost quite a bit less. BUT you will need to contact the manufacturer.

I don't know precisely why it burned up although I assume it's largely due to age and how hard we've used it because it's over 6 years old. And Milwaukee warranties them for 5 years. To get a replacement for the part that has burned up which also includes electronics, cheapest price I've been able to find is about $140. I don't really have that kind of money to throw at the problem right now. But I got this for free, so if I can get some wire for about $20 and spend some time on that, to me that's worth the price and the time right now. Of course it's possible that the electronics are causing an overcurrent condition and so just replacing the coils will only buy me a little more time rather than have it working like new again. But I don't see any other obvious signs of problems, so switching to new coils May reveal where the real problem lies and then hopefully I can fix that before the new coils burn up.

 

Check the motor rated current and fuse accordingly!

 

DEcent quality motors last!! I have motors that are at least 50 years old and are still fine. AND I have a fan that runs a whole lot that is 55 years old. So it is not age, but it might be abuse.

 

Check the motor rated current and fuse accordingly!

I have not been able to find that information for this particular unit. Although watching some other repair videos and additional testing I did find out that two of the MOSFETs are bad, so I ordered replacements for those too.

 

DEcent quality motors last!! I have motors that are at least 50 years old and are still fine. AND I have a fan that runs a whole lot that is 55 years old. So it is not age, but it might be abuse.

If appears to also be the electronics, as further testing has revealed that two of the MOSFETs are bad. This is not likely to be a problem with older motors as they're not likely to have as complex of electronics as we would see in battery powered brushless motors of today.

 

The very first question I have is :Why did the motor burn up?? Certainly there was a reason. Ifyou rewind the motor without fixing the reason that the motor burned up, probably your rewound motor will also burn up.

Aside from that, you may be able to purchase just the portion of the motor that burned up. THAT is because those MILWAUKEE products ARE WORTH REPAIRING. Andthe coils portion of the motor will cost quite a bit less. BUT you will need to contact the manufacturer.

I forgot to tag you in the other replies but this was a very good point. Further testing has revealed that at least two of the MOSFETs are bad. I ordered some replacements.

 

With two mosfets failed there is a question about which failed first? A failed driver could certainly damage a motor, it seems. Adding protective fuses is an interesting possibility, but where to fuse and at what current are challenging considerations.
For the replacement wire, I suggest high temperature rated insulation, if it is available.

 

Let's say I have a brushless motor wound with 18 gauge wire. If I need to replace the winding, and I use the same number of turns but instead I use two parallel 24 gauge wires (which will result and slightly greater cross-sectional area), will it have a fairly similar properties? Or will it be quite different? If it's different, how so?

From experience, it is extremely difficult to fit the same amount of turns with the same cross-section copper area using two wires instead of the original one. Wire stacking and most surprisingly, the enamel insulation thickness will prevent it.

 

From experience, it is extremely difficult to fit the same amount of turns with the same cross-section copper area using two wires instead of the original one. Wire stacking and most surprisingly, the enamel insulation thickness will prevent it.

It has worked out fine for me so far.

 

It has worked out fine for me so far.

For copper magnet wire;

The original 18 gage has 1624 CM.
The proposed 24 gage has 404 circular mils, two would be 808 CM. Half as much copper area than the original . Meaning twice the losses.

If you want and should keep the same losses as the original, you would require a pair of AWG 21.

With heavy insulation build, the minimum requirement for wire used on a motor, the original AWG 18 would occupy an area of 1857 sq mil. while a pair of AWG 21 occupies requires an area 1922 sq mils. More likely in excess of 2000 sq mils because it is hand wound.
It would not fit in a fully stacked magnetic core’s window area. EDIT, unless fewer turns are wound.

I know that this is only an example. But If your solutions so far, have followed the same line of reasoning, then some performance aspect must have suffered.