3 slot or 5 slot brushed?

[aramid]

This is almost a question for Holmes Hobby, since I'm shopping between a Torquemaster and Crawlmaster motor, but I figured I'd put it here since I doubt the question is unique to those two motor lines.


What are the relative merits of a 3-slot vs 5-slot armature? The Holmes site suggests that 5-slot offers smoother startup and 3-slot produces more torque, but presumably there are other differences. Which has better drag brake (especially holding power at a complete stop)? What else does one do better than the other?

 

[Ditchrat]

This is almost a question for Holmes Hobby, since I'm shopping between a Torquemaster and Crawlmaster motor, but I figured I'd put it here since I doubt the question is unique to those two motor lines.


What are the relative merits of a 3-slot vs 5-slot armature? The Holmes site suggests that 5-slot offers smoother startup and 3-slot produces more torque, but presumably there are other differences. Which has better drag brake (especially holding power at a complete stop)? What else does one do better than the other?

You might want to read the have tech questions will answer thread by John Holmes, and if you dont find your answer consider asking it in that thread. He has been pretty active about answering questions, you might as well get it from the man who makes them.

 

[Tufftf2]

I have never run a holmes 3 slot, but have used a 35t hand wound tekin witch is comparable to a torquemaster and am curently using a 13t crawlmaster in my scx10. There is a noticable diffrence but its not night and day. Like you suggested the crawlmaster is smoother on start up by a slim margin but had a good bit more wheel speed even with the crawlmaster geared down. And the diffrence in torque is noticable on the same gearing but is not noticble with the crawlmaster geared down. I will say that if you do go crawlmaster the hand wound is a must, more so then with a 3 slot. The diffrence in wire gauge makes a big diffrence.

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[Jtlittle]

If you have more wheel speed then you have not geared down enough. A fair comparison can only happen when the speed is equal.

 

[Tufftf2]

If you have more wheel speed then you have not geared down enough. A fair comparison can only happen when the speed is equal.

True... I ran both with stock 15 tooth pinions and both with 11 tooth pinions. In both cases the crawlmaster was smoother and faster. When geared the same the 3 slot did have more torque. Imo to get the 5 slot speed from 3 slot the low was a more noticble diffrence. But in reality not a huge change...That being said im comparing, 13 turn and a 35 turn, a more fair comparison would be a 27 turn 3 slot and a 13 turn 5 slot...

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[Rekreant]

From what John says basically the 5 slot has superior low end startup and smoothness, and the 3 slot is very slightly less smooth but better high end.

 

[Rekreant]

I can crawl slower with my torquemaster than any brushless setup tho.

 

[Jtlittle]

Both need to be geared that when at 100% throttle the truch is the same speed. Only then can you accurately compare the motors. For get about wat tooth it takes to get them equal.

 

[Jay-Em]

I always think of 5-poled motors as diesels. Low rpm, with great torque, but no screaming top-end, that can be geared to the moon, while 3-poled/slotted motors are more like 2-strokes, and need careful gearing to prevent heat buildup. Not much happening in the bottom-end, but whooboy when the rpm starts to hit that narrow power-band.

Be it, of course, that an electric motor doesn’t have that “hole” in the torque-curve that a 2-stroke has. That typical ‘nothing, nothing, nothing.. ‘Bráaaaap” èverything of a 2-stroke dirtbike..:ror: A 3-pole/slot motor just sucks more amps to try to get the torque needed at the bottom-end.

5-pole/slot (or more, I even used 12-poles) 700-size electric motors have long been the standard in 14- to 28-cell Hydro’s, because hydro props -with their crazy high pitch- need a lot of torque to get the boat on plane, and need far less once the boat is loose. Meaning battery drain drops significantly, especially at higher voltages.

3-poles could muster the power to get on plane, but at the cost of enormously increased Amp-gobbling ( =heat = bad for magnets) with gassing cells, or even wires coming unsoldered as a result if not careful with prop-pitch.

In my tanks I also prefer 5-pole/slot motors for their low-end grunt. They need more volts to get up to a reasonable speed, but that’s a price I am prepared to pay for their bottom-end, and, yes, ‘smoothness’