stainless steel axle magnetism

[Half Fast Slotter]

Geeez guys! Magnetic axle properties?
This shows the difference between y'all and me when it comes to slot cars.

I squeeze the trigger on the controller and the car goes forward.
When I squeeze harder, the car goes faster.
When I let up, the car goes slower. I try to remember to let up when I come to a curve.
Any questions?
jeff

[wanabgts]

I dont know about you guys, but this is the best thread I have read on here in a long while!

Yes they are just toy cars, but this stuff is what keeps me tinkering away into the early mornings. Hoping I cant keep up with you guys!

Zack

[SuperSlab]

A week or so ago Chris Walker called me to chat about this thread. His take: this is a storm in a teacup. He had quite a convincing basis for this: in the "old days" (and even currently with high performance motors in the really fast classes), those magnets, and the consequent magnetic effect on the axle, are WAY stronger than on the 25K Piranha. And it has no material effect on the performance of the car. So, respecting the source, I took pause.

As mentioned on the GT3 proxy build thread, in the past week I moved the Piranha-motored pod from my Scaleauto Corvette to my Sideways Huracan. And at the same time I decided to test this comment by replacing the titanium axle with a common or garden Slot.it carbon steel axle. Not even the reduced diameter axle, just the common regular one. Note that the pod I used makes use of single flanged bushings: I installed NSR "Self Lubricating" bushings. I assumed this meant they are sintered "Oilite" type bushings. But I must say they certainly do not LOOK sintered, so I am not sure what "Self Lubricating " means in this case. Whatever. As also described in my GT3 build post, the pod and motor did not seem to work well in the Corvette as the car would lose grip abruptly when pushed and start chattering: NOT a good proxy prospect at all.

The character of this pod in the Huracan was the complete opposite: very, very smooth with good grip and not a hint of chatter and with good power delivery. On top of that it really did not exhibit any of the high friction characteristics I was expecting: coasted well and I had to use a fair amount of braking on the controller, and I typical prefer very light brakes.

So Chris: a tip of the hat again as it certainly seems like a regular carbon steel axle is fine when used in conjunction with the high magnetic effect 25K Piranha in close proximity in a Slot.it sidewinder pod. In addition, the driving characteristics of the Piranha motor are quite good.

So I have to say my initial negative perceptions of the motor appear to have been overblown. The performance certainly seems quite acceptable when everything else in the car is up to snuff. Does that mean I will be using it in the GT3 proxy ahead of my normally preferred NSR Shark motors? At this stage I would consider that unlikely purely because I do not feel like gambling on the unknown in a massively competitive proxy as opposed to sticking with the known quantity NSR Shark motors.

Alwyn

[F1Fan]

Very interesting.

[wanabgts]

I would agree that is it a diminishing returns thing to go after this. However I do believe there is more drag with this motor than others, even with the best bushings etc in there. As we know, one little thing doesn't usually make a break you, but they do add up. I guess the point for me was, does this motor really perform well enough to justify it over a NSR etc?

For me the answer is no. If we were doing a plastic track proxy or all magnabraid tracks then I think you could get this to be a real advantage, otherwise I don't see the reason why you pick it over something else.

I had another thought, I tested my car with one of these on a magnabraid track. The handling was actually pretty poor, it was fast but had way more chatter etc. I am guessing this is because the downforce from the motor is actually causing some binding effects on the pod mounting locations. What are your thoughts on this?

Zack

[HO RacePro]

I'm curious. Is there any source for a carbon fiber axle? It would be non-magnetic and, maybe, non-conductive.

A fiberglass axle would definitely be non-conductive.

Ed Bianchi

[wanabgts]

[Brumos RSR]

[SuperSlab]

[chrisguyw]

Hello to all..!!!.....A couple of things to consider when choosing the 25K BB Piranha motor for use/proxy use.

It is a very fine motor, its main benefit/advantage are its neo magnets, which as most have discovered, are considerably stronger than those found in the typical motors used to power the cars most of us run....(there have been similar "neo" magnet motors produced in the past,...the MBSlot "dodo" being the most widely used of the bunch.)

Keeping it simple,..the neos produce a significantly stronger magnetic field than ceramics/metal alloy, and this field results in more torque, and therefore braking, for a given armature wind/stack length. For those that run on plastic track, the significant downforce produced by these neos (via "can leak"/saturation), will result in a car that feels like it has a mild traction magnet. I have not measured the actual downforce that this motor will provide on a plastic track. but, I do have several MBSlot "dodos"(with similar magnets/can) and these consistently post 60+ grams of downforce on a magnet marshal. (The MBSlot "dodos" were discontinued 7/8 years ago, as many Euro clubs thought a "magnet" motor in a no magnet class was a bit of a cheek, considering the widespread use of plastic track overseas).

For wood track racing, some will like/appreciate the added torque (therefore braking as well), and, as neos are generally lighter than ceramic magnets, the motor is a tad lighter than some, which can have positive handling effects when installed due to a lower "moment of inertia".

So, while I do think the motor is quite nice, there are some things that you may want to consider for proxy events.

While quality ball bearings can/do offer some advantages, there are some things to keep in mind......quality bearings are not cheap, far from it, and it is more than generally accepted by virtually all commercial track/international racers that a sintered bronze bushing offers more benefits than any inexpensive ball bearing.....the less expensive ball bearings have less precision, and therefore, more slop than a sintered bushing........this can result in movement of the motor shaft, which negatively effects both gear mesh and handling.
Additionally, the bearings do not hold oil like the sintering in bronze, so....the bearings must be oiled much more frequently to avoid wear/seizing. If the proxy rules allow hosts to inspect/oil motor bearings, that is one thing,....if not, a sintered bronze bushing motor may well be more advisable.

I have nothing bad to say about this motor,....I do like it, but, I understand its potential limitations, and will use it in only specific circumstances.

Cheers
Chris Walker

[steeveew]

I'm using one of these motors in the Can Am proxy,it seems like it has less braking than the standard Piranha motor.


Steve

[chrisguyw]

[Gentleman Norb]

[steeveew]

[dw5555]

I did a motor conversion test here on Carrera 1/24 cars back in Feb, and this was one of the motors tested. (Carrera Track) I know this is an apples to oranges comparison to what your doing here but I found the braking comments interesting. I needed more brake with this motor than any of the others I tested and this was 2nd motor from the bottom in torque. I found the std Piranha motor had better brakes. This is an excerpt from my write up. The cars weighted in at 235gr so they had some oomph to push around.
Dave

PIRANHA BB MOTOR: 12V BEST TIME: 10.201
SPEED SETTING: 100%
BRAKE SETTING: 50%
UNLIKE ITS SIBLING THE LOWER VOLTAGE DIDN’T AFFECT THIS MOTOR AS MUCH. LOW END POWER WAS STILL GOOD AND COULD TAKE MORE IN THE CURVES AND EXITING. THERE WERE A FEW SPOTS ON THE TRACK WHERE IT WAS WIDE OPEN WHERE IT WASN’T BEFORE AND YOU COULD SEE IT WAS DOWN ON POWER. ONE THING I FORGOT TO MENTION IS THIS MOTOR LACKS SOME BRAKING COMPARED TO THE OTHER MOTORS. I HAD TO INCREASE IT BY 10%. NOT A LOT BUT IT IMPROVED DRIVEABLITY.