The Motor Construction Thread aka What Motor should I Get?

[Espeefan]

Excellent thread, John. Very well written. Even though I have some good motor experience and knowledge already, you've taught me some new things. This thread should be a stickie.

Two questions, though. You lightly touched on the hand wound motor subject. I knew hand wound motors made more power, but I've never tried one. Just how much more can I expect, if all else stays the same in a given set-up? Enough to warrant the extra $20 or so? In other words, is it really that noticable?

What really makes a hand wound motor better? You said they have more copper in them. Can you explain this? Why would it be any different then a machine wound armature?

[EddieO]

I can answer this for ya.....I think Holmes is on vacation...

Handwound motors provide more power than a machine wound equal, but there is no definitive answer. It's never been really tested much in racing, as machine wound classes in general don't allow handwound. There was some carry over in oval with the 19t class though, as they allowed handwound 19t motors, as long as they were in the same can as the machine wound. Two popular motors were the Reedy Quad Mag 19t and the Trinity C2. When we would build those machine wound, they would be in the mid 160s for watts. If we would handwound them, we would see mid 190s, so yer talking 30 watts, which is a LOT More power. And this is just on a 19t....power increases on modifieds would be more substantial, but a a definitive answer is tough.....mainly cause I as a motor builder can't really machine wind a 55t mod to compare to. I can't get the integy teardowns they use really, and wouldn't cause my experiences with their motors is that are made of not the best materials with fairly cheesy designs.....I had a failure rates that are through the roof with their 19t and stocks.

So is it worth it, I would say yes in a heartbeat......is it noticeable, well, I have never had a crawler customer complain they couldn't notice it.

What makes a handwound better, that's a lot easier to answer. First and foremost, you can much better windings, even if its not pattern wound. A sloppy handwound is still better by far than a machine wound motor. Copper gets packed in MUCH MUCH better, so you can more copper fill (other wise known as circular mills). Now keep in mind, this is a weird term. You want more copper in the fact of BIGGER wire, which is more feasible because of the handwinding, as you can pack it in better, but you want the overall length to be as SHORT as possible. Short and fat =more power and more efficient. Think of it as a fire hose......you want as much water as fast as you can....how do you do this? A FAT and SHORT hose......that's how power gets through a motor.

Handwound motors are typical either silver solder or silver welded, which is a MUCH better bond to the comm. Machine wounds are almostly ALWAYS compression welded....which sucks. It's not strong, resistance is much higher, so in the end, you are losing power and more likely for failure. This is big time important when you are stalling out a motor and it's drawing 100 amps.....weak links make things go BOOM.

Next up is epoxy, which is a bigger deal than most people realize. Epoxy holds the windings in place, keeping the motor in balance. It also increases heat disipation. Strong windings are extremely important to the motor lasting. Machine wounds do have epoxy, but its done the worst way possible. One of two ways is usually used, they either spray the windings (most common) or brushed (fairly uncommon). Handwounds done by quality motor companies, are DIPPED. Dipping is the only way to get make penetration into the windings. You want that epoxy to flow all through the windings, which doesn't happen with the spray or brush methods. An easy test for this, take some maple syrup.....spray it on a sponge, brush it on a sponge, and then dip a sponge in it......what gets the most syrup? I think the answer is obivious. You can test this by unwinding a machine wound motor and then get any quality handwound motor, the machine wound will unwind pretty easy, like just a flimsy glue holding it together......you will be lucky to even get a few strands of the handwound arm undone.

Epoxy then needs to be cured. Machine wounds are usually flash baked, which usually exposes them to a high heat for a minimal amount of time, or they use an epoxy does not need to be baked, it basically air cures. The best epoxys to use all require heat curing. You are getting a weaker epoxy on the machine wounds, but the best stuff is used on handwounds. Quality handwound arms are typically baked for 90-240 minutes, depending on the epoxy.

Comm cuts are done with diamond bits and measured by hand. You are getting a comm thats as perfect to round as we can get it. Machine wound motors, are simply cut to a preset on the lathe.....regardless if it makes the comm round or not. Out of round comms cause a loss of power, increased amp draw (aka heat), premature brush and spring wear, and it effects balance.

Balancing is very very different on machine wound vs a handwound. Handwound arms use precision balancers, made to balance ONE arm when done with the winding, soldering, epoxy, etc processes are done. Machine wound arms use a very very weird process. The winding machine often attempts to correct balance as it winds the motor. Remember how I said SHORT wire? Well, the machine usually adds wire to attempt to correct balance....BAD BAD BAD. They are then touched up on a machine thats much different than the ones we use. The machines I use (I have three) cost 9k, 10k, and 4k(this is an older portable model, not as good as the other two). Our machines allow us to balance much more efficiently, hence why you often see less and smaller holes on our arms.

A last thing to note on is the ability to modify whatever you want in the process with hand winding. You can change wire sizes, patterns, you can double dip the epoxy, and more. Machine wounds are all set to the pre determined settings and left to run.....there is very little human interaction inthe process. Think Homer Simpson pushing his button at the power plant.


Also beware, not all handwounds are created equal. Integy handwounds are done very very shody. If they were a 7 turn, they would explode within the first minute of a touring car race. They use very cheap epoxy, and sometimes its just sprayed on. They are not very good at the welding they do, and it spreads the comm plates far past whats acceptable and soldered versions use a a poor solder with the wrong type of flux, which is why the joint always looks nasty. Typically they are using a much smaller wire than they should, which is not always a bad thing, but it does produce less power, but it makes them much easier and cheaper to wind.

If yer looking for a good handwound motor, stick to the companies that actually do it (or a quality reseller like Holmes or JP) right from start to bottom. I know my company does it right (team brood racing), as does Fantom, Banzai, and Trinity.......really the only companies doing quality handwound motors for crawling applications. We do a ton of other things to these motors to justify the extra expense for them.

So simply said, the extra $20-$40 you would spend on a quality handwound motor is easily worth it. Look how much you spend on all the other stuff in your crawler. $100+ each for berg axles, $140 servos, $160 ESC, etc, etc......with a $20 motor? Look at any real crawler or race car, the motor will always be among the most expensive, if not the most expensive item on the vehicle.

Sorry for the long winded post, if you have any other questions, lmk.

Later EddieO

[JohnRobHolmes]

I couldn't have said it better.


In a nutshell, yes you will tell a power difference from an Integy 55t to a pro handwound 55t.


ps. the thread is already in the motor sticky at the top.

[Espeefan]

Thanks for the very informative post. I've learned a lot more about motors, just by reading all that has been typed. EddieO, I appreciate your excellent explaination. By far, this is one of the best posts I've read on the subject.

[EddieO]

Not a problem...

The scary thing about motors for crawlers, is they seem to be the forgotten link. People kinda just slap them in and forget about them....and run them on every course.

I think over the next year, you will see more and more people pay attention to motors.

You will see people running different motors on any given weekend, cause what works at venue A, might not be the hot ticket at venue b. Really no different than tires.....

And you are going to see more and more people figure out that motor needs a good rebuild often. Though motors in crawling are not spun up to crazy speeds, but they are exposed to insane amp draws, sometimes that rival or even exceed what we see in carpet racing. Crazy amp draw burns brushes and comms, which means a rebuild for top performance.

I think the evolution will start as we see more and more people coming over from the racing arena.......course they are gonna be pissed caused they have to run brushed again, cause from everything I seen, brushless kinda sucks for crawling.

I will be here to provide a lot of education on motors.......cause, like John Holmes will tell you too, we have really only scratched the surface of the whole thing.......still a TON left to learn. I've been racing for 20+ years, running Team Brood since 2003......25+ national titles later, even I still don't know everything.

Maybe the mods will let me do a Ask EddieO about motors or something....gotta renew my membership tonight.

Later EddieO

[JohnRobHolmes]

We may see the falling out of brushed motors soon. As you and I know Eddie, good teardowns are hard to find anymore. It is like pulling teeth to get nice stuff made now, and we can just hope that good old Sagami doesn't throw out the tooling too quick.


Brushless only sucks because nobody has really put some money into a system for crawling. New motors made from brand new ideas are needed to fit the bill, not just rewound 3 slot sensored brushless.

[EddieO]

Yeah, while it could be an issue......its not gonna be for me for a while...


The biggest problem with brushless, is it just doesn't have the feel from what I gather. I tested some stuff specifically wound for crawling on special motors......engineer assured me it would feel just like a brush.........it didn't, it sucked, so we sent them back.

Part will still apply though......motors will need to be clean and kept going....and what works at some places, won't work at others, as brushless motors still follow the same physics.....

And one thing, brushless and water don't mix well.........brushed, you can run through the mud if you want.....

Later EddieO

[JohnRobHolmes]

Brushless works in water just fine. Some constructions with sensors don't like getting wet, but a bl motor can be submerged no problem.

I edited your post since you don't have a star.

[Espeefan]

Yeah, I was going say, non-sensored brushless motors shouldn't have a problem running, even fully sub-merged, in water. I'm really new to brushless so far, but I am experiementing with my Clod based Huster. The motors I have don't seem to be bad, as far as low speed control, but I do think brushed motors have a little better low end resolution. Nature of the beast, however I can't really complain about the brushless motors I am using either. They don't cog at all, have decent low speed control, and they don't seem to bog down at all, even at the lowest RPM.

[EddieO]

Fixed the star issue.........I tried right after I made that post, but something was fubared with paypal...

Brushless is a weird animal when it comes to water.......in general, they should have no issues, but some do, some don't. Hence why you still see deep sea stuff still using brushed, as they know it will work. I talked to a couple of brushless vendors in RC, a lot of their returns on Sport System Brushless stuff is water damage to the motor.....

I think the big problem with brushless in crawling, especially for a crawler specific designed system, is gonna be cost. I would probably say 70% just run cheap Integy motors, and we can't convince them to spend $50 on a good brushed. A crawler specific brushless is going to be $75+ easy, as even trinity can't get their 17.5 under $60 to a much bigger market.....smaller market=higher price. I just don't see any company taking the plunge.

In the end, I think it just boils down to performance.....brushed works amazing for crawling....and people are so used to how it performs, it might be a tough sell. I think it says a lot when Novak and Tekin, both just say screw it and start selling a brushed crawling motor. Last I heard, neither have a new design for brushless crawling in the works, just keep using the other teardowns to make them.

Later EddieO

[JohnRobHolmes]

Brushless doesn't use cheapo magnets, so that is one cost increase. Typically the laminations are also much nicer than brushed, another cost increase. You have to hand wind most brushless stators too, another big cost increase.


You will see my company take the plunge into it. I have three designs I am working on. One is cheapest (adaptation of existing tooling), one is very powerful, and the third has the best startup. I think people would buy a nice brushless system, since they are not spending money on a "replaceable" motor that wears out.


I agree that brushed is the gold standard though. It is sure hard to beat the performance.

[axial-aaron]

Excellent information in here....

I have a question that I'm hoping you can help me with. I have a 90t handwound atlas motor, with no torque... I'm wondering if adjusting the timing would help this??

If so I'm not sure how to even go about it as the motor has wires soldered to the can that prevent me from adjusting it.

Any help with this would be most appreciated. I have been scouring the net looking for answers on it.

Thanks.

[JohnRobHolmes]

Some forward timing would help, but adding voltage would really give you some power.

[EddieO]

Adjusting the timing ain't gonna help your no torque problem by itself. You will gain power by upping the timing, so to get the torque you want, you will have to adjust your gearing to get it. More power should help.....upping the voltage will help also...

But I gotta ask, how does a 90t have no torque?? 90t seems way too many turns for most crawlers, as the motor won't make power at all. Can't even use a 90t on lathe, won't spin fast enough unless you give 6+ volts. I would look at going to a 45t or 55t, solve all your problems at once.

If you can provide a pic of the endbell of the motor, I am sure John or I can tell you how to adjust the timing.

Later EddieO

[axial-aaron]

Thanks for the info! My wife got me the 90t for xmas... it was a nice gesture. So I'm playing around with it. My other motor is stock 27t for now. So the 90 is keeping me busy till I get what I want for under the hood.

Will get a picture of the end up here asap. Thanks again.

[CreepyCrawl]

Originally Posted by JohnRobHolmes

We may see the falling out of brushed motors soon. As you and I know Eddie, good teardowns are hard to find anymore. It is like pulling teeth to get nice stuff made now, and we can just hope that good old Sagami doesn't throw out the tooling too quick.


Brushless only sucks because nobody has really put some money into a system for crawling. New motors made from brand new ideas are needed to fit the bill, not just rewound 3 slot sensored brushless.

Fantastic thread John, thank you.

Personal preference for me, I will always run brushed motors in my crawlers. I feel that brushless motor set ups simply cannot replicate or compete with the smoothness and accuracy that a brushed motor delivers.

I've wheeled a few 2.2's with brushless set ups and while they were nice, for my drive style, I found them to be a bit too twitchy at very low throttle input.

So for once I hope that you're wrong...I'll take brushes and comms any day of the week

[friskylizard]

Hypothetical question...If I were very green with little time running a brushed motor, would i be a better candidate for brushless, since i never developed a driving style? or gotten used to brushed motors?

I have an axial and really don't like the motor or the ESC lack of low speed control....

Great Forum....

Thanks

[crazy_kanaka]

Excellent information here.

John... I spend a lot of my free time reading your posts. Thanks for putting in the time to write all of it up.

[axial-aaron]

Originally Posted by EddieO

Adjusting the timing ain't gonna help your no torque problem by itself. You will gain power by upping the timing, so to get the torque you want, you will have to adjust your gearing to get it. More power should help.....upping the voltage will help also...

But I gotta ask, how does a 90t have no torque?? 90t seems way too many turns for most crawlers, as the motor won't make power at all. Can't even use a 90t on lathe, won't spin fast enough unless you give 6+ volts. I would look at going to a 45t or 55t, solve all your problems at once.

If you can provide a pic of the endbell of the motor, I am sure John or I can tell you how to adjust the timing.

Later EddieO

Hey EddieO...

I finally got around to those pics.






The wires that are soldered to the can are preventing me from adjusting.... do you advise on unsoldering them, and resoldering in a new spot????

Thanks for your help ....

[JohnRobHolmes]

The timing is fixed on that motor, you can't adjust it anyway.