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Old 11-23-2008, 10:48 PM
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Motor testing results Week of November 17th

Well, I did some motor building this week (the one thing I did besides deer hunting, lol) and not to mention lots of testing and experimenting. In a discussion that Flashsp-2 got into a while back, we brought up the availability (or the lack there of) of specialty blank armatures (ie, slotted, spiral slotted, long) and the such. Auldey is the company, however, they don't seem to produce these anymore. They were origninally intended for Tamiya Mini4wds, and some smart bloak figured to use them in our motors. Problem is, there is limited supplies.

I purchased 5 blank spiral armatures, and 2 FAT commutators (1 silver, 1 copper) from a dealer in the UK ( and recieved them a while ago and have been doing some testing with them. I found a few interesting facts that average motor builders may not realize right away:

So between 7 armatures (techincally 6, ones on its way to SPR), 5 spiral and 2 regular I found that the spiral armatures had much more room on the poles than regular RS armatures. The pole was also thinner. While this translates to more winds on the pole, I was pleased to see that it kept the stack patterns alot lower, and closer to the iron laminations. This, at least so it seems to me, increases the motors efficiancy. It seems that the closer the top layer of the stack pattern is to the pole, the stronger the armature. Instead of having a 42t pyramid with 7 layers, I had a pyramid with 5 layers, and 1 wind on the head of the pole. Much easier to wind, IMO, plus more effcient.

The 15 degree spiral twist on the armature also had a devastating effect. Since the stack pattern was delightfully low profile, I expected the low end torque to be lacking, because the winds would be shorter than a taller stack, however, the torque was off the chain even with Iso mags! With basic armatures, you get dead spots between the poles/coils. In effect, the spiral armature twists the coils over some of these dead spots, increasing magnetivity which in the long run transfers to torque. So not only did a 41t with a FAT comm outperform (torque wise) a 42t, it beat out a straight wound 39t with a standard comm/rs armature.

Hemi winding too, is one thing I'm going to be doing alot more of. Although it seems backwards to me, changing the direction of the winding has no effect on the direction the motor will spin, because electricity always flows through it the way it usually does (the wire technically does a full 360). I hemi wound all of the spiral armatures so far, and they seem much smoother than typical cross wound motors. Of course, alot of this isn't noticeable when dropped in a typical xmod someone using fine precise drivetrains (ie, blt45's 64 pitch differntial) will feel the response, especially on a flat smooth surface such as a carpet, or rcp track.

Another item I got to experiment with was the silver FAT commutator. BOOM!! Thats all I could think of when I tested it, lol. Its as big around as any FAT comm, its just instead of copper plates, it uses silver, an element probably twice as conductive. The results, IMO were devastating. The armature I wound 35t hemi wound, standard short RS armature was explosive in its response. Every bit of juice flowing into that motor found the silver. It seems that some motors don't use the given power very well. Arcing and poor commutator conductivity can often times be the culprit. The silver comm with fully broken in carbon brushes was deadly. The low end was raised slightly, and top end stayed about the same, but the response was great! I'll be getting more of these if I can...

The hemi wound motors have equal discharge times on a 1.5v AA battery, as compared to a standard cross wound armature, however, the spiral motors last a minute or so longer than standard. Taking into consideration the differences in pole lengths, though, its not surprising. I'm trying to develop a motor right now that peaks out run time on NiMh batteries, as that would be a very big hit with racers. However, this can be tricky, and I have a feeling a gRed (check my SP thread) armature would be better than a spiral or other type.

Overall, my motors are headed more in the direction of speedy response, and smooth operation as of the November. However, that doesn't mean that they will be wimpy. Combine fast response with torque and high top end, and you've got an almost perfect motor. If I can get a source for specialty motor parts, they will deffinately be incorporated into my motor lineups.

Feel free to comment or respond.


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