27 replies to this topic

[Pablo]

....but ya never know until ya try

I'm still not 100% convinced the super strong magnets in this motor don't create added friction to the rotation of the axle. That's why I obtained both carbon fiber axles and a tungsten axle to try.

I know the carbon fiber won't be near as strong as steel and I know the tungsten weighs a ton right where and how you don't want it - rotating heavy mass up high.

 

The Dungeon Raceway has a "two-minute rule" to fix a car that dies. I don't like the rule - guys use it like a free pass to not have to maintain their cars until they fail. Anyway, I figure if I use the carbon fibers and snap one occasionally, the rule will help me for a change.

 

The new 2019 rules allow the Phoenix in GTP, so this is my actual race car. New motor, new 13/36 64P gears, C43 chassis. My plan is to compare amp draw at 5 volts using:

-a standard hi-quality axle

-a tungsten axle

-a Professor Motor carbon fiber axle

 

Shown here is the tungsten, and I already learned one good thing, even if the experiment is inconclusive - using a non-magnetic axle makes Phoenix motor installation a thousand times easier

 

[Greg Erskine]

Looking forward to the result Paul. 

 

Logic dictates there must be a difference but how minute? Will it be noticeable?

[Pablo]

We know logic doesn't always apply to slot cars.

There is only one truth: lap times

[MSwiss]

1/24 commercial axles are made from the material they are, for a reason.

Tungsten and carbon fiber will snap in a wreck.

[gotboostedvr6]

Those spur gears are junk I would definitely ditch it. They strip extremely quickly.

[W. J. Dougherty]

Whatever happened to Ti axles? I know that folks ran them for a while. Were they also too brittle? Too expensive?

[Pablo]

1/24 commercial axles are made from the material they are, for a reason.

Tungsten and carbon fiber will snap in a wreck.

 

Concur.

 

But, The Dungeon is a special case - deslot or wreck and you just dropped 3 positions anyway.

Car breaks, you got 2 minutes to fix it. Any other place in the world I wouldn't even try it.

 

Guys are abusing the 2 min rule to wait until lead wires or motors fail instead of checking them during a post race inspection.

Why can't I have an emergency 2 minute carbon fiber axle with a wheel and gear ready? Snap. 2 mins. Back in the game.

 

If it wasn't for that rule, I wouldn't do this. Onward with the experiment. Disclaimer: don't attempt this yourself.

If you are sane, use a high quality slot car axle (Koford)

 

All ye who enter my experment cave, abandon hope

[gotboostedvr6]

I'm also pretty sure I see a ball bearings back there. Any added resistance you feel from the strong magnets will not be a problem. I've been known to dig trenches in the back of my magnets to get the axle one paper thickness away from the actual magnet. Moving the motor back and more parallel to the axle will produce faster lap times.

[Pablo]

Amperage results:

-motor installed by itself, no load, .74

-standard hi-quality axle, .82

-tungsten axle, .77

-carbon fiber axle, .74

 

My conclusions:

-using a non-metallic axle to install the motor makes the job much easier

-super strong Phoenix magnets do, indeed, pull on a metallic axle enough to create measurably added friction

 

Will this info be useful at the track? Maybe, maybe not.

My next part of the experiment is to test lap times with a standard axle vs. a CF.

If there is a huge improvement, I may actually race test a CF.

 

Of course I'll have a standard axle/gear setup at the ready in the pits to take advantage of the 2 min. rule

[Greg Erskine]

Interesting results!

 

To test your assumption further, you could try a strong external magnet near the metal axle. By moving the magnet closer and further away your should see a dynamic and repeatable change in current.

 

EDIT: I suppose a nearby external magnet could affect the motor directly.

 

regards

Greg

[Ramcatlarry]

It is a lot easier to mount the Phoenix with the red dot in front/label front - more room for soldering the brace.  Test the spurs range for torque coming off the corners and burning up the motors.  36T - 38T work differently on different tracks and power systems..

 

Try a Stainless Steel hollow axle as well, it will be much more true running than a carbon fibre one. The magnetics are much lower than regular steel.  Titanium parts are not that much lighter than steel AND expensive

 

I always use an M2 #42 drill blank (3/32"). It is a lot less likely to shear compared to the stiff M7 'higher quality' blanks.  M2s do not bend, either like piano wire/unhardened ones will .

[gc4895]

Great thread! Is it just me or do these Phoenix motors brakes leave something to be desired ??? Im geared 13/37, in a C43, Parma HD body. Wow, the power curve is something to behold. I had terrible wheel spin up the main straight, then traction kicks in and it takes off like a rocket. Strange motors. Really wish it had brakes. YES, what a problem to solder into place.

[Half Fast]

I am surprised that the Phoenix only draws .74 amps considering that a Hawk Retro draws around .5 amps at 5 volts. At what voltage was the Phoenix measured?

 

Experimentation is always good, as you learn something from even failed experiments.

 

Cheers

[Pablo]

Test voltage as stated in post #1 was 5 volts.

 

Thanks for the hollow axle idea, matter of fact I have a Koford qualifying axle here somewhere........I'll test it.

 

Label was installed in the front, the motor was just sitting loose in the photo.

[Pablo]

Thanks again, Ramcatlarry

The Koford M339 draws .78, and it stays on the car

I'll get another and put a wheel n spacers on it in case it snaps.

 

Am I worried my competitors will find my secret? No.

They're too busy watching cat juggling videos on unsocial media.

They haven't even caught on to CL flags  yet   

 

Whaddaya know, this experiment worked (I think)

[A. J. Hoyt]

I'm not positive but I've seen devices that count on eddy current damping in space-based mechanisms using copper plates moving between two un-powered field coils. When they flip a switch (that shorts out the field coil), the eddy current damping effect of moving the copper plate between them is profound, stopping the pendulum motion in less than two cycles.

 

Take-away - copper is NOT magnetic - it is only a conductor.

 

It makes me wonder about a rotating shaft (axle) within the magnetic field of a motor. I think the eddy current damping works on most any conductor and manifest the effect you are seeing in the test results. If these assumptions are correct, the damping would occur with ANY metal axle.

 

You may have also discovered that the effect is minimized somewhat with a hollow axle. Is that your take-away?

 

By the way, the hollow axle reduces the high CG (and rearward and overall) mass somewhat but the rotational (polar moment) inertia is a function of the 4th power of the radius, so rotational inertia benefits for an hollow axle is pretty small because the outer radius is what counts against you, not the core.

 

Bending stiffness decrease is minimal (function of the 3rd power of the radius) so crash damage due to bending resistance due to a crash impact is still quite good for a good grade of steel with proper heat treat. There is, however, a better chance of buckling at the point of resistance (ball bearing or bushing) but that is offset by the additional hoop support in the buckling area due to the inner ball bearing race or the ID of a small ID clearance bushing.

 

If the eddy current damping is really occurring, the no-load draw in amps might not be the best indicator of total torque power delivery to the tires while under load. but the damping IS proportional to the speed so there might be a top-end limiting factor, but that is also the case with the increased damping of the stronger magnets ...

 

Another thing to consider: I have been told that super strong track magnets on unlimited class HO cars expend a significant amount of their power overcoming the eddy current damping of the magnets moving relative to the rails. I'm not sure that the effect is actually a combination of eddy current damping and vastly increased rolling resistance of the tires with related increased axle friction.

 

Just my 40% of a nickel.

[Greg Erskine]

Looks like we need to look at mu-metal motor shields.

[bluecars]

Don't know about all the hallabaloo of strong magnets and unobtanium axels but soon as I get done watching cats juggling videos I guess I better look for my container of ball bearings.  

[Pablo]

BB's been legal in GTP at The Dungeon for a loooong time.

2019 is going to be lots of fun

[bluecars]

Can't use them with my axel location. yep, lots of fun for turn martials.

[gotboostedvr6]

Not following.. fun because?

[Pablo]

"Can't use them with my axel location"

As we say in Mississippi, "dat don' make no sense,   'splain it to me"

 

"Fun", I can explain:

-In 2018 we used H7 motors in GTP at The Dungeon and the cars were blazing fast - for 2019, the Phoenix is allowed. Katy, bar the door. 

-a few of the regular racers perform zero maintenance on their cars (they only have a month) and they handle unpredictably.

 

We're gonna snap some metal, bend some wheels, and destroy some bodies

[Pablo]

Experiment is done. GTP race yesterday at The Dungeon was the first time the Phoenix was allowed. 

I used a Koford hollow. Guys with standard axles were blazing fast, passing me like a blur. (I was slightly under-geared)

 

Now that I got that out of my system, next time I'll have a bigger pinion and a standard Koford axle.

Shoulda just listened to Swiss but I enjoyed testing my theory

 

I will be using the carbon fiber and tungsten axles to solder my Phoenix motors in - makes it much easier not having to fight the magnetic field   Onward........

[swodem]

Pablo

Gearing before was 13/36?
Gearing changing to?

What were the others running?
Steve



Sent from my iPhone using Tapatalk Pro

[Pablo]

Ask me in a PM, please. I'll gladly share the info.