Motor winding questions

[luke213]

So guys I've got a question that I've been thinking about. Backstory time for another motor for one of my builds however back in the day motors weren't nearly what they are today. I've got a couple Neodymium motors, which are awesome for power etc. But I've run into some questions I haven't been able to dig up answers for or at least not exactly what I'm looking for.

So motor strength the way I understand it is tied to the strength of the magnets as well as the gauge and number of wraps of wire around the armature, and TPA is basically a measure of wraps on the armature. So more wraps is higher torque and lower speed, and more wraps is faster speed with less torque. However what I'm curious about is how the gauge of the wire effects both power use and durability along with torque and speed. So building something like a frankentorque motor which is typically a high TPA armature in a neo can, which seems like it would leave thinner gauge wire which would be more prone to failure.

I'm considering wrapping my own armature just to do it so I can understand it, but I'm trying to figure out I guess if there is a benefit to trying to go with the largest gauge wire possible while getting the wraps I would like as well. Or I guess more details on how those things work together. I'm sure there has to be some info out there I just haven't been able to find it. But I mostly want to understand more deeply how all of the components of our motors work and what causes what functionally within the motor. IE Torque vs speed etc, and how various changes effect that balance.

This may be beyond the normal knowledge of guys here not sure how in depth guys have gone into this side of things but even a point in a direction where there is more info would be appreciated. I've been reading some on Airsoft Mechanics and getting some info, but still can't really figure out who gauge plays a role in the equation.

Take care!

Luke

[Stinger]

The benefit would be a larger gauge can carry more amperage. You typically don't run into issues with this in motors, however, as you'll blow the commutator or brushes before the windings go if current is too high.
I'm curious to see what you find out, though. I wish I had the time to play around with tech stuff again. Winter break, perhaps...

Also, if you haven't already, watch my video about motors:

[luke213]

That's part of what I'm curious about, so I've had a couple motors arc out and fail, however I never dug into what failed and tried to figure out why. I've actually got one right now that threw sparks and stopped but I haven't had time to tear it apart and see what failed. In my head though I guess it makes the most sense the wires wrapped around the armature would be the common failure point since if they are a fine wire we're dumping allot of current through them with heavier builds.

So as an example lets say a gearbox is setup with 16ga wire run through a mosfet with a 11.1v lipo. That full force of current is pushing through say 24ga wire wrapped around the armature, and it's a long 24ga wire which is going to increase resistance. So in my head at least I see 16ga dropping to 24ga wire the 24ga wire is going to get very hot if enough current is pushed through it and the point of failure is going to be the smallest wire or point of the most resistance.

Now that also leads to the thought that higher TPA means less heat which seems counter intuitive to me at least. It seems like the larger gauge wire carrying the more current would run cooler. And further down that rabbit hole, say two motors both run with 24ga wire one with say 12TPA and one with 22TPA it seems the motor with 12TPA is going to have lower resistance because it's a shorter wire at the end of the day, the 22TPA wire will be longer and thus higher resistance with the same wire material and gauge. That's the sort of thing that I'm really trying to further my understanding of, because it seems like there are some contradictions in some of the logic when it applies to DC motors. And likely there are other effects in play here that I don't understand which might explain some of this stuff. Since it's so much taken as common knowledge I'm curious what is driving these different things. Much like why is higher speed less efficient than higher torque. It would seem the efficiency would be about the same with appropriate gear ratios IE high torque motor on high speed gears vs. high speed motor on high torque gears.

I know this stuff isn't important necessarily to building a good functional gun but I'm a bit of a geek and I like to understand the underlying principals that dictate the behavior of stuff;) It's just the way my mind works;)

Oh and while I'm thinking of it, frankentorque motors. High TPA neo cans, seems like while it would have very high torque because of the space requirements on the armature it would make them prone to wire failures on the wraps because it's going to be smaller gauge wire to fit that many wraps. So that's part of where my thinking is above as well.

Take care!

Luke

[Stinger]

Each individual wire does not carry the full amperage. It's distributed by the commutator.
The reason why more windings creates more torque is because you generate a more powerful magnetic field (running a current through any wire generates a magnetic field, more wires means a more powerful field).
Higher TPA motors generate less heat because they pull less amperage, which is also why they're more efficient. The magnetic field is stronger, so less amperage is required.
I've never seen failures on the armature because, while you do have small diameter wires, they're bundled. Keep in mind that for large industrial applications (thousands of amps), power cables are made of bundled wires. The concept is the same. The more likely point of failure is at the motor brushes.

[luke213]

I might not be understanding this;) But it seems to me that the wire is taking the full load, since it's run directly off the commutator well when the brush contacts the commutator that completes the circuit until the brush passes to the next contact. So it seems like while the brush is on the contact the wire should be taking the complete load.

The windings and more magnetic fields makes perfect sense, I don't know why I hadn't thought about it like that before but that makes perfect sense.

Well on failures I've seen some on the armature from the wire, but I'm not sure why if the wires worked their way out and were cut by the magnets passing the armature etc. But I have seen that in pictures etc, but I've not diagnosed my own failures to make sure what happened yet.

Very interesting though I appreciate the input since this is clearing up some of the things I was wondering about.

Luke