3573 replies to this topic

[havlicek]

That fits what I've seen about doubles Mike. I think the rpms are pretty close to the "equivalent" single wind, with maybe less torque...but that softer torque curve could be desireable for more "driveability". They may be less efficient in terms of raw horsepower per volt, but they may be more efficient with less-than-ideal power.

-john

[havlicek]

I've gotten some PM inquiries about multiples and basically, I tend to "believe" my own experience over what people tell me about arms (although there are a few people here whose experience I do trust because I know they've "been there"). So here's some pictures:

I wound a #28 dbl. on one of Bill Bugenis' eurosport blanks to send him to play with. On such a short arm, it was a tight fit up top near and under the com...but it wasn't that bad. More importantly, I was able to weld the com without any trouble. Even on straight com tabs, a #27 double seems like it would be doable without having too much trouble welding, but I'm not sure how the wind would work under the com height-wise. In any case, a #28 double on such a short stack is a very low resistance arm and should be plenty hot enough. Here's the arm wound, welded and tied. Bill would (as always with the eurosports) do the epoxying, stack grinding, balancing and shaft grinding (if applicable) down to 1.5mm:



For reference, here's a #30 triple wind (I think...it may even be a #29 triple...I forget, but most likely a #30) I did a year or two ago on a long Mura .007" lam stack with a Mura com. ** Correction, I just noticed that the stack engraving seems to say it's a #29 triple I DO get carried away sometimes!!! The arm is an absolute terror, but I haven't found a good use for it so I save it for whenever the opportunity pops up. I originally built and spaced it for a 2-hole Mura setup, but it's a ridiculous arm:



Neither of these are "layered" or "series" doubles. Both were wound with multiple conductors being fed simultaneously. I don't know that either is "better", but I suspect this way "might" be better.

-john

[Prof. Fate]

Hi

I always had better results with two or three parallel wires on a simultaneous wind rather than layered.

The limit is always that of the set up, however. No Scaley S can is going to take a 30 double!

Fate

[havlicek]

I always had better results with two or three parallel wires on a simultaneous wind rather than layered.

Makes sense to me Rocky, although I don't have anything more than an educated guess to go on.

The limit is always that of the set up, however. No Scaley S can is going to take a 30 double!

Sure...but setups have come a long way. Yes on the S can also...but they can be cut down, have a real end bell fitted, magnets replaced and so on. There are always lots of neat and interesting projects to attack.

-john

[Allen00]

Is their a rule of thumb to go by on triple and quad winds? I know a double is equivalent to 3 wire sizes smaller. So is a triple equivalent to 4.5 sizes smaller and a quad 6 sizes smaller? Would a 30 turn quad wind 32 gauge be like a 30 turn 26 gauge?

[havlicek]

I've seen the equivalency specs for triples and quads but have forgotten them Allen. I don 't see doing any triples and certainly no quads anyway, so I'm not worried about it. I'm sure someone here knows and will chime-in.

-john

[Don Weaver]

When winding more than two wires it's best to use "circular mils" to calculate the equivilent wire size.

Don Weaver

[Marty N]

Is their a rule of thumb to go by on triple and quad winds? I know a double is equivalent to 3 wire sizes smaller. So is a triple equivalent to 4.5 sizes smaller and a quad 6 sizes smaller? Would a 30 turn quad wind 32 gauge be like a 30 turn 26 gauge?

A 60/28 wound as a 30/28/2 would be the equivalent of a 30/25, wound as a 20/28/3 would be the equivalent of a 20/22, and wound as a 15/28/4 would be the equivalent of a 15/20. 3 gauges for a double, 6 gauges for a triple and 8 gauges as a quad. In practice it isn't quite this neat due the extra lengths of wire going to and from the tabs but this is pretty close.

[Allen00]

I tried a 30g quad today on a old 36d arm. 3 feet of wire, 4 strands on each pole got me 23 turns and .6 ohms. The motor sounds good and only pulls 1.10 amps at 5 volts and run cool. It sounds like it has a little more rpm than my 30t26g single that pulls more amps and gets warm on a single pass at the drag strip. I'll try it this weekend and see if it stays together.
I don't know how the math works out, but this motors not that extreme. 8 sizes smaller would be a 23t22g single.

[havlicek]

Hi Allen,

I tried a 30g quad today on a old 36d arm. 3 feet of wire, 4 strands on each pole got me 23 turns and .6 ohms.

I don't know how the math works out, but this motors not that extreme. 8 sizes smaller would be a 23t22g single.

Very cool!...let us know how it worked. Like I said, the "equivalent" winds don't really work out, the cross sectional areas of the singles and equivalent multiples may be the same, but there's something else going on here. In this case, the extra jumbo arm of the 36D gives you lots of room for wire which is a good thing! How did you manage the com connections...did you pigtail them? With a quad, the first/last com tab would have 8 conductors!

-john

[Marty N]

I certainly don't have all the answers but one thing that is going on is that the shape and size of the coil is altered between the single and equivalent multi which alters the inductance. When done as a layered wind the coil is often smaller in cross section, less "air" between the wires decreasing inductance, more rpm, less torque. In an "in hand wind" the wires tend not to be at right angles to the field and torque becomes the average of the combine slip angles, again less torque, more rpm. While the coil is slightly larger giving some back it is also "looser" thus less interplay between individual conductors. No rule says that multiple conductors all have to be the same gauge either. RC winders have done this type of wind for some time and call them differential winds. Never played with them myself. One item to keep in mind, especially if drag racing multi's, is that it is pretty easy to construct a winding that will have the ability to draw more current than the track can supply. Another is that the large increase in EMF at the pole can exceed the magnets coercive force knocking them flat in a hurry.

[Allen00]

Hi John, yes I did pigtail the wires. I'm just winding by hand so the 36d is easier to work with.
In the early 90's I raced R/C cars and some of the best motors were quad and quint winds. They had more rpm ,drew less amps and had less torque so they were easier to drive.

[Prof. Fate]

Hi

This is an old and possibly unreliable memory, but what I remember from when I was doing these was "3-6-9-12", 2x30s are a 27, 3 are a 24 and so on.

Fate

[havlicek]

No rule says that multiple conductors all have to be the same gauge either.

Sure thing and mixing conductors is probably as old as rewinding in slots. 28/29 was a popular one, and those arms are still out there as NOS or just "old" The information I got here was that allowed approximating half-gauges...makes sense, but good magnet wire in about all full and half gauge sizes is readily available now so it's probably less important. Of course if you were really developing a wind for a certain car and track, it's possible that a mixed-gauge wind would be just the ticket too.

-john

[Allen00]

Well the quad wind has potential, but it may be to much for the old 36d coms. I made one pass and the com exploded at 3/4 track. It crossed the finish with the rear tires locked and still ran a 1.29 at 36 mph. Oh well its fun to push the limits of these old motors.

[Marty N]

Try again with one of Bill's commutators

[havlicek]

Hi Allen,

What Martin said! Sounds like you do have some potential there though because, an exploding com is one sign of horsepower!

-john

[Allen00]

The coms are the weak link on the 36d's. I'll try the wind again, maybe on a 360 round can arm with the new style com. I liked the low amp draw that it had on the power supply.

[havlicek]

Hi Allen,

Yes, the coms are pretty weak, although for mild rewinds (single #29) they seem OK. 36D endbells have enough room for modern coms, although sometimes the inside of the hardware and plastic needs to be clearanced a little to make room for the com tabs. If you come across any, there was a Champion 36D commutator that was much better and should work for short blasts (I think) on a 36D drag car. I just wound three 36D doubles for a Blogger and he had me use Mura coms, and those have to be reamed-out for the larger shaft size of the 36D. I really don't like doing that as the com cuts vary in depth and on some coms, the larger hole seems to come too close for comfort...but he tells me they've been doing this apparently without many problems!? The big fat modern Mura "Diamond-Cut" coms have more material and seem a better choice for this, but if you ever decide to try this, don't drill out the shaft hole. A twist drill will torque it's way slightly off center going through the tough phenolic. A small burr or (if you can find one) a tiny reamer is better. I may try a 36D quad sometime thanks to your inspiration ...good luck!

-john

[havlicek]

Lots of motor work lately, but this one stood out to me as particularly sweet. Barney (Team Cort) sent me a Champion can w/Arco magnets and end-bell for a 26D build (maybe a Proxy car motor if it gets back to him in time). Barney spec'd the wind as he was going for more torque/brakes/reliability than raw speed. The arm blank is a Tradeship to which I mounted one of the excellent Bugenis coms with a mild advance. Wind is a #29 single, com was welded.



The endbell got 36D hoods and heatsinks (brush tubes) that were clearanced on the inside for the larger com, aligned and soldered...as well as a set of post protectors. I widened the can countersinks for the retaining screws and that was about it. With a set of Camen springs, the motor sings a sweet song, drawing only about an amp or even a bit under but pulling strong all the way to 12V where it really sounds like a rewind After a couple of minutes at 6V, the motor was still getting stronger and running cool. Brakes and torque seem really good too..."Houston, we have liftoff"!



-john

[HarV Wallbanger III]

Wow John that looks sweet! I hope I can finish the car now as I had a accident with a "helper" Sat. and my arm was in a cast till today. A Early Bronco trans and T-case landed on my wrist....... Pic is before I went to the emergency room and still swelling.

Thank you very much John! U DA MAN!

[havlicek]

You're always welcome Barney Sorry about your arm, I can relate. It was my fingers against the saw a couple of weeks ago, and the saw won...as usual, but it only hurts when I touch things Anyway, the motor pulls nice and strong and it should be a very solid and reliable runner. With the larger hardware, changing brushes will be a snap too since you don't have to source the smaller ones. There was very little to no arcing at the com I could see, so you probably don't need much if any break-in. A drop of oil on each bushing and you should be ready to go!

As is often the case with the 26D's, the coil is pretty close to the rear of the can so it you use a rear bracket, make sure the screws aren't too long.

-john

[HarV Wallbanger III]

Thanks John,
It's a good thing I'm right handed.... self abuse is hard... offhanded!

[Victor Poulin]

Another nice job John ! Your work looks even better each time I see it didnt really think you could do any better than you've been doing, but somehow you manage to out do yourself lol.

[HarV Wallbanger III]

The arm looks great John. Thank you again!

I forgot to show you my "arm"