Wobbling Axle/Wheel Combo

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rferrin
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Wobbling Axle/Wheel Combo

Post by rferrin » Mon Jan 20, 2014 2:55 pm

I etched a notch in the axles right under the head and down the axle head a bit as well. It seems that the axles that are not etched don't wobble when I spin the wheels on the axle but the ones I etched do. Did I do something wrong here? I also made the axle heads tapered with the derby worx pro axle press.



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Stan Pope
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Re: Wobbling Axle/Wheel Combo

Post by Stan Pope » Mon Jan 20, 2014 3:24 pm

Does this (more or less) match what you ended up with?

Image

Depending on the width of the notch, it may or may not reach inside the wheel bore because the step in the outer hub may prevent. Can you tell whether?

Even if notch reaches the bore, it should not cause a disturbance in the wheel, because (I think that) the wheel's CM is safely outside the notch so that the wheel will want to lie flat on the axle rather than tip into the notch. Can you tell?

If above is true, then check the axle shaft next to the notch to see if its diameter was affected by the notching. Are there any irregularities near the edge of the notch or under the axle head that could disturb the wheel. If none, then I don't know what is causing the wobble.


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Re: Wobbling Axle/Wheel Combo

Post by Speedster » Mon Jan 20, 2014 4:15 pm

I have a grooved .091 stainless steel axle in front of me. Immediately under the head there is a VERY narrow groove that I cannot measure with a caliper. I can see it through a magnifying glass. The tapered end of the caliper is too thick and when I try to measure the groove it measures .091. After the tiny groove the axle measures .091 for 1/16th of an inch. After the 1/16th of an inch the axle drops down to .071 for an 1/8th of an inch. After the 1/8th of an inch the axle returns to .091 for the length of the axle. Under the magnifying glass the groove directly under the axle head appears to line up with the other groove and I'm going to assume it is .071.

A few questions if I may.
Is this a BSA Made in the USA axle?
Are you using graphite as a lube?
Why are you grooving the axle?
Can you use an axle Made in China?



rferrin
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Re: Wobbling Axle/Wheel Combo

Post by rferrin » Mon Jan 20, 2014 4:56 pm

file:///C:/Users/ryan/Google%20Drive/Bubba%20Cubscouts/axle.JPG

Don't know if you can follow that link or not but the one on the left is what I was trying to do and it ended up like the one on the right with a rounded notch instead of a squared off one. I wonder too if my axle head is lopsided from the axle press or from filing it in the drill press.



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Darin McGrew
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Re: Wobbling Axle/Wheel Combo

Post by Darin McGrew » Mon Jan 20, 2014 5:03 pm

URLs that start with file:// refer to files on your local filesystem. No one but you has access to it.



rferrin
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Re: Wobbling Axle/Wheel Combo

Post by rferrin » Thu Jan 23, 2014 9:03 am

Sorry I didn't answer all your questions timely, I guess I asked the question 2 days before his race thinking that I had time to help him correct it if I thought it would effect the wobble too much. Anyways his race was last night and he took first place by a landslide. He won every race by at least 2-3 race lengths and now he gets to go to district race where I think he'll face more competition.



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Stan Pope
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Re: Wobbling Axle/Wheel Combo

Post by Stan Pope » Thu Jan 23, 2014 1:50 pm

rferrin wrote:... Anyways his race was last night and he took first place by a landslide. He won every race by at least 2-3 race lengths and now he gets to go to district race where I think he'll face more competition.
Well, whatever wobble was there in your "unloaded spin test" must certainly have gone away when the wheel was carrying weight! Congrats to your team!
:clap:


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Re: Wobbling Axle/Wheel Combo

Post by Speedster » Thu Jan 23, 2014 5:29 pm

Congratulations on the WIN !!!!

Might we see a picture of your car and give us the details of your build.



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