1441 replies to this topic

[tonyp]

Thousands of times. A couple of wounds.

[Half Fast]

Yet, you have never been hit by lightning... hmmmm.

 

Cheers,

[Brinkley47]

I have a different rules question.

 

Is sanding the comm legal if you can do it in the can?

The race director (Brandon) at the Fall Brawl said a racer showed him a tool that could do this pretty easily. I have not seen the tool but am confident it exists.

I haven't tried to make it work because I always questioned the legality.

Is it OK if the can is not messed with?

[old & gray]

Ever have your hand hit by another car while marshaling one?

 

Yes, once hard enough to leave a mark.

 

In that case it was a brass and wire chassis that was in the process of disassembling itself during the race. (I was reaching under the bridge for a car and was hit by the car on an adjacent lane.) The only way I could see to prevent this type of problem is to inspect for cold solder joints at tech, which is not a real possibility.

[Tex]

Ever have your hand hit by another car while marshaling one?

 
Very rarely... and getting hurt by such even less. The IRRA^® BoD has addressed the situation. Nothing more needs to be said; of course, we're slot racers... that's never stopped us before. LOL.

[CDavis7]

I have a different rules question.
 
Is sanding the comm legal if you can do it in the can?

The race director (Brandon) at the Fall Brawl said a racer showed him a tool that could do this pretty easily. I have not seen the tool but am confident it exists.

I haven't tried to make it work because I always questioned the legality.

Is it OK if the can is not messed with?

It's been asked before and the answer was that it was not legal. Its most easily accomplished on motors with accessible hoods and removable brushes. It can be done on a FK motors as well.

But, as stated, it was previously ruled to be a modification of the motor.

Unless the BoD has a new opinion.

[MSwiss]

I don't remember that it was brought up before.

 

The discussion we are having about it, on a private forum, there wasn't any mention of "we answered it before."

 

Please feel free to point out where we ruled on it.

[Bryan Warmack]

I've never done it but can easily see a tool being made to carefully get inside and sand the comm and would more than likely be completely undetectable. If no one could detect this modification how would it be policed?

[MSwiss]

Bryan,

 

Some unofficial comments.

 

If the motor was protested, and taken apart, I think you could fairly easily detect it was sanded.

 

I know if I had the microscope we had at Koford, I probably could.

 

That said, I seriously doubt you could true the comm better, than the factory, that does it pretty precisely.

 

Unless reducing the diameter dramatically, somehow would help, and if that was the case, again, it would then be even easier to detect.

 

All the above is just my opinion.

 

No official  IRRA^® statement has been crafted.

[Bryan Warmack]

Mike,

 

Yes, from what I've seen with the stock comms on any of these FK motors, I can't imagine sanding of the comm in any manner would have any positive effect on performance...

[Brinkley47]

I think if a person sanded the comm on a raced motor there would be a difference. I have seen some pretty trashed coms after run time.

Maybe there is no advantage. That would make it a non-issue if that is the case.

[bbr]

If you are able to get the comm concentric...

[Samiam]

I have used a comm polishing stick on sealed 501s and 502s. This just cleaned the comm. 

 

I was told never sand a comm. Ever! The grit becomes imbedded in the comm. 

[gotboostedvr6]

Grit has little to do with why you should not polish or use any means other than a lathe to retrue a comm.

 

Grit can be removed, the problem is with making the comm out of round. When you rub the comm the leading and trailing edges of the comm segments wear first. The wear reduces diameter and deteriorates contact with the brush face. This reduced contact accelerates brush and comm trailing edge burning.

[Samiam]

Worked for me.

 

I'm talking 16Ds here. Spun with a Dremel on low speed for a very short period of time. Less than 10 sec.

[gotboostedvr6]

It's possible for a comm to be in such bad shape that mechanically cleaning it by means other then a lathe might improve performance for a measured, short period of time. Considering a 130FK motor has a 25 minute lifespan i guess my argument is moot.   

 

After cutting comms thousands of times and building hundreds of motors I'm confident in my prior statement. I'm part of  the do it right the first time crowd and am not a fan of doing things if I'm not putting sufficient effort to a means worthy of such efforts.

[Samiam]

In the case of sealed motors, doing it right is illegal. 

[CDavis7]

I don't remember that it was brought up before.
 
The discussion we are having about it, on a private forum, there wasn't any mention of "we answered it before".
 
Please feel free to point out where we ruled on it.

I must be mistaken then.

So please rule on it publicly. Are tools such as the Trinity Comm Tool or other polishing type implements legal to use, so long as the motor has not been opened or otherwise modified?

Thank you in advance

[Brinkley47]

I have sanded a PS-FK comm with success. In fact, Custer's world championship motor ($500 winner) was built this way so I know there can be speed there. I used 1500 grit sandpaper with oil so I don't know how much sanding I was actually doing. I then used a pencil eraser to finish it off.

Honestly, I hope in the Hawk case, it doesn't help the motor.

[MSwiss]

Yes, I think with 1500 "grit," it's not called sanding.

 

You probably would of had a better chance removing copper, if you spun the comm on a baby's ass. LOL.

 

I'm guessing you removed the hardware , and was able to wrap the sandpaper around the comm, before spinning it in a Dremel.

 

Needless to say, with an FK, it would be a different scenario.

 

Just curious, were you able to document an improvement? IOW, was the motor tested before and after? If so, how much did it pick up?

 

Regardless, your post is the reason why going to a Hawk 6, or a 4002FK, is the IRRA^®'s last choice for an improved motor.

 

We are just trying to eliminate motor tuning.

[Brinkley47]

I tested rpm on one PS-FK a long time ago and the comm cleaning did improve RPM. Around a 1000 I think which is not a ton. The amp draw leveled out, which is why I started doing it on all PS-FK. On Custer's, I just built the motor that way before he put it in the car. I did the same with my motors and one of Sharf's motors that weekend.

Once I got a method I liked, I just kept repeating the same process.

I will say the newer PS-FK I don't even straighten the hardware. Those motors are ready to rip out of the package it seems. They have definitely gotten better over time, IMO.

I have never felt like I got cheated or outmotored using a Retro Hawk. However, as a competitive racer, I am always looking for that extra .001 sec if I can get it.

[Richard G With]

I am skeptical about the sandpaper method. Wouldn't the paper just curve into the worn area, making the track from brush wear deeper? It surely wouldn't be able to make the comm rounder.
 
Also, in the case of the PS motor, I'd fear that anything that removes comm material would aggravate the
excessive brush overlap, and lead to more push start problems.
 
Really, the current crop of Pro Slot 4002FK motors seem to be equal enough that it isn't worth saving a
worn-out motor unless you just happen to have a really exceptional one.

[Richard G With]

I have built an F1 similar to the Fang concept and am wondering if my front axle uprights will pass IRRA^® tech. See the pictures attached.

 

I think its legal according to Section E Body, point 2c:

 

"Chassis visible from the top via a legal opening, such as the front or rear axle area, are permissible in this class, providing no part, other than the axles and/or axle tubes, exceeds the maximum 1.625 chassis width."

 

I'd prefer to submit to a virtual tech inspection now rather than keep building and find out I'm doing it wrong.

 

 

[Dominator]

Hi Richard,

Nice variation to the FANG. As long as the uprights are no wider than 1.625", then you are good to go.

[raisin27]

I remember a post somewhere from awhile ago that showed a F1 chassis that had metal "control arms" sticking out past the body. They were intended to give the car a more scale appearance. Even though they were for looks and not a performance edge if I remember correctly they were deemed illegal.