23 replies to this topic

[Phil Smith]

This is an interesting way of skewing a motor. The magnet plates are skewed instead of the armature.
 
Unused in Box Original Early 1960s Tradeship Inc. Micro Motor MK-70 12V
 

[chaparrAL]

Also 5 pole?

 

 

   Looks like a "star" wind. 

                

 

 

 

 

 

                  

[Eddie Fleming]

And adjustable timing? 

[Ramcatlarry]

Too bad it was still Alnico magnets - no torque or brakes.  Very smooth, though used the twist of the Lindsay armature in a more easily built motor.  As an inline, the magnet mass was better used near the drive tires.  Had one in the day, the ceramic cans were already becoming dominant.  The next adjustable timing I recall is the Russkit 34 which I never found chassis made to fit.

 

Was Tradeship also alternate branding of KTM and Kemtron?  The armature winds sure seemed the same.

[Phil Smith]

What is a "star wind", Larry?

[zipper]

Grab from Wikipedia, brushless DC motor. (wye = star)

[don.siegel]

It was indeed adjustable timing Eddie. 

 

Not sure of the actual manufacturer for the Tradeship motors, but all of their stuff was imported from Japan, so there could be a link. 

 

Don 

 

PS: two of the Tradeship motors with some contemporaries: 

[tonyp]

Maybe for a model train. The skewed “can” would make it have smooth acceleration which is something train engines look for.


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[Pitt Man]

Here's a bit of info on these MK70's from a handful of years ago.   

 

 

http://slotblog.net/...adeshipdynamic/

 

[Dave Crevie]

Exactly, Tony. The skewed arms and higher pole counts were for smoother performance at low RPMs, and consequently

were used mostly for model trains. Bob Colson of All Nation Line had a close relationship with Pittman and was able to

get me a couple of three-pole arms for the DC-85 frame. Even after re-winding, they were slower off the line in my unlimited

rail. I went back to five-pole arms and the times came down.

[havlicek]

BUT, skewed-lam 3-pole armatures with hot winds in say a C can motor can be an excellent choice for a slot car (*not so much for a train, unless it's a scale model of a bullet-train) 

[Dave Crevie]

Never tried rewinding a skewed arm. I'll except your opinion, but I do know that back in the day we discarded skewed

arms as a matter of course. I have no idea who originally said skewed arms were no good for slot car racing, only that

I, as well as all the pro rewinders, did not use them. You have started me thinking, though. I have plenty of skewed arms

laying around, I might give it a try now that I have more time. 

[havlicek]

The funny thing about skewed-lam armatures is that they are a little schizophrenic by nature.  Yes, they make for the kind of smooth low-RPM performance that is suited to model trains, because the pole "crowns" are effectively seen as "wider" by the permanent magnets they oppose (*and attract).  Wider-crown laminations in general (*when stacked normally) produce less "cog" and smoother spin-up and spin-down, and 5 pole arms with their REALLY narrow slots and wide crowns even more so.  Model railroaders' motors often have both 5 pole AND skewed lam armatures.  

Here's the "other side" of the schizo skewed-lam armature.  When wound hot, you still get very a very fast motor, but with less of the "lightswitch" characteristic...call it more "driveability".  Now, a person who is used to fast and furious hot motors may need to do a little getting-used-to the somewhat different performance, but others might just like it right off the bat.  ***In any case, there is definitely good reason to investigate skewed-lam 3-pole armatures for slots.  They're a little bit of a bother to wind, but nothing "deal-breaking" after you do your first pole.

[MSwiss]

When I worked for Koford, they were tried, just for the heck of it.

For G7 wing racing, I don't remember if they were determined to be inferior, or just no better, but it was never persued, more than 1 or 2 arms.

IIRC, they might of also been a pain to balance.

[tonyp]

Our RC pure gold motor back in the day was a skewed blank modified motor designed for 2wd off road buggies. Lots of top end with a soft acceleration to get the tires to hook up.


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[MSwiss]

We run Group F with spray glue on Wednesday nights and once a month.

To go fast, you have to remove the pans.

Everyone takes a turn popping, including the top racers.

I wonder if a skewed arm would cure that, not that it would ever see production.

[havlicek]

We run Group F with spray glue on Wednesday nights and once a month.

To go fast, you have to remove the pans.

Everyone takes a turn popping, including the top racers.

I wonder if a skewed arm would cure that, not that it would ever see production.

 

 

I have no idea what "Group F" is Mike, but if you want a skewed-lam arm that fits whatever a "Group F" setup is, let me know.  I doubt they would ever be produced also (? there is a bit more fiddling involved in making the arms, but Alpha has'n't mentioned any difficulty in balancing them) but there IS something there.  Barney Poyner was the guy who got me interested in them for slots.  IIRC, I think he had some done by Big Jim Greenaway that were "bank-slammers". 

[MSwiss]

I'll pass.

 

Even if it worked better, with no chance of it seeing production, it would just be a tease.

 

BTW, I recently spotted one of your arms in a motor where a production arm was supposed to be used.

 

Not your fault.

 

All my fault, for being so naive, to think hosting a race with no tech, wouldn't lead to questionable motors (not very common) , or way too low of clearance(more common).

[Horsepower]

Too bad it was still Alnico magnets - no torque or brakes.  Very smooth, though used the twist of the Lindsay armature in a more easily built motor.  As an inline, the magnet mass was better used near the drive tires.  Had one in the day, the ceramic cans were already becoming dominant.  The next adjustable timing I recall is the Russkit 34 which I never found chassis made to fit.

 

Was Tradeship also alternate branding of KTM and Kemtron?  The armature winds sure seemed the same.

Lawrence  my good man, you are a veritable fountain of info! Just FYI, Dynamic made a chassis for both the MK 70 and the Russkit 34. Ebay has them now and again.

[Ramcatlarry]

Thanks HP!   In 1963-1966, I was paste soldering brass tubing frames with my Weller gun.  Rarely saw any of the nice Dynamic kits.  I have built a few of those and Kemtron kits in the past few years.

 

I have two different 1960s transistor controllers to get working this winter, ambition allowing the diversion from racing Retro, ISRA, and 1/32 plastic cars.

 

Pekka - from your graph, 'N" is the commutator. and 'Delta' is how I understand all permanent magnet motors are wound.  Star/wye looks like something I have seen in 3-phase AC motors. Both AC and brushless DC have no commutator(?).

[havlicek]

I'll pass.

 

Even if it worked better, with no chance of it seeing production, it would just be a tease.

 

BTW, I recently spotted one of your arms in a motor where a production arm was supposed to be used.

 

Not your fault.

 

All my fault, for being so naive, to think hosting a race with no tech, wouldn't lead to questionable motors (not very common) , or way too low of clearance(more common).

 

Sorry about that.  I feel badly that some people might be doing this, but I think this is the first time I've been told for sure.  When people come right out and ask me to make them a cheater, I always turn them down.

[S.O. Watt]

Heres a skewed mag motor from around 86/87 when Jon Laster and I were trying to get the unlimited Camen strap motors to work in 1/32 euro cars over in europe. The Italians were really liking them but the developement was brutal to get them raceable.

We were still using production open arms and had way too much grunt. I ran sometimes up to 40ft of choke and still had too much punch. So out came the dremel and we created a few of these. They worked surprisingly well and became an advantage a couple of times.

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[Horsepower]

Thanks HP!   In 1963-1966, I was paste soldering brass tubing frames with my Weller gun.  Rarely saw any of the nice Dynamic kits.  I have built a few of those and Kemtron kits in the past few years.

 

Lucky dog! A Weller! I had to borrow an iron from the guy who lived across the street. . But soldering frames with borrowed equipment and no Dynamic store bought frames made us use our hands and heads. You don't see that combo much any more.

[Dan Miller]

I tried the skewed armature thing twice. Once in Open Gp.7 back about 1985 and again in Scale in the late 1990's. No real advantage. Maybe if you made very special setups to run them in but they clearly did not outrun my other armatures with straight stacks.

 

Came close to reasonable performance in 1/32 Formula 1 action. The motors lacked some power but the cars were smooth on acceleration. The problem came from having to increase the height of the magnets to gain back brakes as well. Plus, while the acceleration was smooth it always seemed "late" and response was delayed. Also the F1 stacks I make are quite short so there is not much to skew.   

 

With multiple poles, small wire with many turns and low timing, I would think skewed stacks for train duty could be a good choice. Not for slot cars that want to go fast.

 

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