Motor Poles and...

[strummer57]

I've come over from the model railroading world, where smooth performance is a must and 5 pole motors are the norm. As a general rule, how many poles does the "average" slot car motor have?

I ask this because there seems to be a bit of a "clogging" action to all my Scalextric cars' motors, so I'm guessing they are 3 pole and so their low speed action is not great. These cars are all in like new condition, with very little track time and have been properly lubed...

I get it that at racing speeds, 3 poles are probably just fine, but wouldn't a 5-pole run just as fast...and smoother?

Also, is there any advantage to a can motor over an open-frame type? It seems that for maintenance reasons alone, an open type would be easier to access commutator, brushes, etc. I seem to recall that there were some open frame types used "back in the day".

I will be most interested in hearing your responses... :)

Mark in Oregon

[SuperSlab]

I suspect it is all about cost and fit for the purpose.

I believe most of the common closed can motors are three pole. This I believe is probably due to the fact that it is less expensive to manufacture and for 99% of the target market this is completely adequate. I must say I have never had any concerns with low speed behaviour of any motor because, as you mentioned, at racing speeds it is irrelevant. I believe then that better low RPM smoothness falls into the category of "the perfect solution to a non-existent problem" for the target market as I have never come across anybody that needs or wants a motor that is smooth and easy and proportional to control in the bottom 1% of its speed range. Or even 10% for that matter.

I suspect the same answer also applies to the open frame vs can motor question. Small can motors are so inexpensive they are pretty much considered consumables. On top of that they are good enough that, even though they are not maintainable, for most users they run perfectly well for the time that people use them. Anything more or "better" would add cost from which the typical user would derive no benefit.

Alwyn

[strummer57]

[chappyman66]

I have 5 and 7 pole vintage motors. Remember that early slots were powered by train motors so that's the origin. Three poles are cheaper. Low voltage performance can be adjusted with gearing.....
Open frame (strap) motors provide less weight and more cooling. For wing car racing you can mount them much lower in the chassis. Can size is largely dictated by arm diameter....the Gr7 strap motors are neodymium magnets too.

[SuperSlab]

[chrisguyw]

Hi Mark, Good responses from all those above,..... but, there are some other factors involved.

Motors are one of my favourite topics, (and a very very involved one) but, I will keep this response fairly simple/low tech.

In the early 60's there really was no other choice for a motor to power a model slot car other than 3/5/7 pole train motors, they did work well, and were certainly developed over time by Pittman etc., to more meet the needs of the emerging slot car industry/market. While they did get quicker, and lots of go faster parts were introduced, they were still on the long side (magnet on one end, and long armature) and were basically only useful for inline configurations. Enter the Mabuchi 36/26/16D motors (early/mid 60's) which were much shorter in length, and while not only more powerful/higher revving they critically allowed the motors to be placed in sidewinder/anglewinder configurations, Additionally, the 26/16 D motors were significantly lighter, which greatly enhanced handling.

Current "Open" motors are a long long development progression of the 16D, but are today much much smaller, much more powerful, and will rev in the 150+K range with massive torque........this all costs money, and these are in the $300 and up range per motor, with costly rebuilds required after every race.

By contrast, the motors powering our little plastic cars are not designed for slot cars at all, they power electric toothbrushes, electronics, car mirrors etc. and while the slot car companies, (Slot-it/NSR etc.) can have some input into magnet strength/arm wind, they are essentially "off the rack" made by Mabuchi/Sun etc, who produce millions of these motors.

To keep costs down, particularly for the tiny percentage of motors the slot car industry uses, conformation to a motor manufacturer's offerings is essential.

As far as 3 vs 5 pole,.....well, 3 pole is less expensive to manufacture, that is why the major motor manufacturers produce them this way, and if well balanced, they are perfectly smooth.......well up to 150_K

If you are looking for a motor (slotcar) that is rebuildable, ProSlot has a EuroMk1, that will keep you happy, and it is no more expensive than motors from Slot-it/NSR etc.

Mark, this a very simplistic explanation, (my two typing fingers get tired)......if you need more please holler.

Hope this helps.

Cheers
Chris Walker

A few early train/slot open frame motors (mainly Tyco)..........long buggers, but still a lot used in Vintage race meetings



An "open" GP27 motor (still 3 pole).......two thirds the size of a Slot-it 21/25K FC130 motor........unbelievable power (and cost),.....and you will need in excess of 10 amps to make it tick over.

[waaytoomuchintothis]

I, too, came from trains, back in 1962. I still built trains until the 1980s, but they were O Gauge for other people by contract (100 boxcars, 50 tank cars, 200 hoppers, etc, all in various road names). Me and Floquil wore out some air brush needles. I remember the "pulse power" transformers that made not-so-good motors run smoothly at very slow speed. Slow and smooth was everything in quality locomotives.

But slot cars were my meat from '62 on. The open frame motors that were manufactured for trains were everywhere at first, but then more and more of these motors were made for slot cars, too. I liked them because I could "get into" them for repairs and tuning. The Mabuchi "can" motors at first were easily tuned, but more and more, the size of the can and the purpose for the motors made tuning impractical in most cases. As others have said, the motors became purpose-built, and when they failed, they were tossed economically and replaced with consistently identical replacements.

I am curious about your perceived needs in slot car motors. Are you making scale model race cars to run at scale speeds? If so, that's a small fraternity. A lot of us have tried to get that done, and for most of us, the transition to racing just can't be beat. I don't recommend all out speed that is beyond what a human can watch, but there is a world of fun that lies between very, very slow but realistic, and crazy fast. Let us know what you are up to?

[slothead]

Years ago I was disappointed by not being able to drive slot cars slow enough to simulate rolling restarts as happen in dirt racing all the time. Getting slot cars lined up and having them proceed slowly in formation is nearly impossible.

I for one would love slot cars that ran at more realistic speeds if skill was still needed to drive them. I've often wished slot cars were more like digital trains when it comes to acceleration. Trains depart a stop in a realistic manner, while slot cars go from zero to blur (or massive wheel spin) in a heartbeat. I know speed is king to most racers and slower just couldn't make sense to them, even if the racing was more realistic. Crash and burn racing is one way slot car folks put an emphasis back on sensible driving over all out speed. Only rarely in 1:1 racing can a car/driver recover from a spin or crash and still record a top finish. (That's why Danny Sullivan's 360 spin and win at Indy remains one of the most amazing things I've seen in racing.)

There's a lot of tuning conversation on HRW, but I don't recall that including motors except related to putting a lower RPM motor in a car to make it more driveable. Thankfully, home track racing is a different animal than commercial track racing where the quest for speed left realism behind to die many decades ago (in many cases).

[RichD]

Running a slot car at a realistic scale speed would be like watching paint dry. A slot car has a guide flag or pin so it has more more grip at the front than a 1:1 car. Unless the tires have almost no grip a slot car will be capable of very high scale speeds. When I got into slot racing back in the early '60s a few cars had five and even seven pole motors. Today all modern slot cars use three pole motors. Cost is always a consideration, but does it really cost much more to make a five pole motor? I suspect that for slot racing applications three pole motors offer the best performance. Take a look at the very expensive high performance 1/24th motor that was pictured in an earlier post, if there was an advantage to having more than three poles that is what it would have.
If you want to run your cars at very low speeds part of the problem is that a slot car does not have a transmission, the cars are not geared to run at low speeds, you have to punch the controller to get them moving. Your controller is likely to be part of the problem. A controller with a higher ohm rating than you would normally use would be better if you wanted to do a low speed rolling start, but it would probably increase your lap times during the race itself. With an electronic controller you could turn the sensitivity down and get good low speed control, but you would have to turn it back up for the race.
If you are looking for more realistic speeds and you are running cars with traction magnets the first thing to do is toss the magnets. Next you might reduce the track voltage, many clubs that race without traction magnets do that at 10 volts. Even at the reduced voltage cars without traction magnets will have about the same top speed as they would with magnets at the higher voltage.

[strummer57]

Wow, this has gotten more input than I would have imagined; thank you all for chiming in so far!

I guess what I am "up to" here is simply that I don't care for the excessive speeds these modern cars run at; it seems they are either all or nothing, with very little in between speed control. The speed is almost dizzying and for me anyway, not all that enjoyable. These modern rigs are pretty much "full on": only by the grace of the magnets do they adhere to the track. I was able to remove the magnets from the NASCAR cars, but am unsure how to do the same with the open-wheel and sports car models. And as I think I mentioned elsewhere, substituting the original "wall wart" for an old Aurora pack definitely helped, although I'm not sure why... :?

Although it was a long time ago (1965), I think I remember the 1/32 (Aurora) set my brother and I had as having cars that were "quick", but could actually be driven; that is, you could accelerate on the straightaways and slow for the corners...you know, like the real thing. :)

I have a couple of vintage cars on the way (including an Aurora car) so I will run them and see if my memory of those old cars is correct; if not, then I guess I will have to look at other factors, like the controllers, etc. In the meantime, please feel free to continue to share any thoughts you might have; it's all helpful and appreciated...and fun to read!

Mark in Oregon

[chappyman66]

If you want to drive the cars, go no-mag. I haven't met a magnet I couldn't remove....but they do require you to remove at least the body and sometimes other parts to get at the magnet or give it enough room to be removed.
Once the magnet is out, you learn about having true wheels and tires.....and your introduction to the tuning process has begun. You can drive the cars now....and everything changes.
And...fwiw....the 3 pole motors do just fine in the no-mag cars. ;)

[SuperSlab]

Doh! Stupid me: I did not even for a moment consider the possibility that you were running magnets! That makes your situation far more understandable! For your needs: absolutely lose the magnets. Also consider:

* Dropping the track voltage to a level that you prefer
* Consider an adjustable controller. I do not know other controllers but with my Slot.it I can adjust the starting sensitivity (not that I use it....), the controller response curve (again, not that I use it...) and also the maximum voltage. With these settings I am sure you can get the characteristics you desire.

Alwyn

[strummer57]

Thank you...I guess I should have titled this thread "Motor Poles and Magnets"!

All my current cars are newer Scalextric, except for a Carrera D-type Jag. As I mentioned (I think) the mags in the NASCAR types were simply held in with some sort of contact cement and were easy to pry out and remove. Control of these (in conjunction with the older Aurora power pack) are now vastly improved. The little "button" type magnets in the other Scalextrics are buried inside the cars and I haven't looked into removing those yet: any tips?

The Carrera had (2); one was easy to remove, but the other one (with the adjustable "sliding" feature) is held in place by what looks like part of the frame casting itself, beneath the motor. Here's a couple of pictures: you can see the different position(s) of the magnet:


Jag 2.jpg

Jag 1.jpg

I bet the downforce of these magnets work to compromise the low speed of these cars; after all, that's a lot of added "friction" to overcome...

I'm finding all this stuff quite fascinating... :)

Mark in Oregon

[chrisguyw]

[strummer57]

Thank you Chris for both the advice and for agreeing with me! :D

Coming from a builder of your considerable talents that means a lot...to take nothing away from the others who have commented as well... :)

Mark in Oregon