Rail Riding - First Attempt (failure, sort of)
Posted: Sun Feb 04, 2018 8:47 am
Good Morning All,
This thread follows my earlier post about indenting the "RR" wheel...
The good news is that my cub scout won 1st place overall in the pack. He was happy, so that's all that really matters, except that from what I observed, the car was not a rail rider, despite our attempt to do so. I stood at the end of the track and observed the car wobble on the guide rail, although not as severely as the other cars.
Two cars were built... one for my cub scout, and one for my youngest son who participated in the sibling race. I observed the same wobble in the sibling car. The sibling car also won its two heats, but the races weren't timed, and the car only ran on 2 of the 6 lanes, so I am not sure how it truly performed. Car construction was intended to be the same. Brief summary...
The front left wheel was raised. The front right wheel had a positive cant (toe in) of 1.5 deg. The body of the car near the front right wheel was indented 1/32" of an inch. Both rear wheels had a negative cant (toe out) of 2.5 deg. The spacing between the body and the front right wheel was 30 thou and the spacing on the back wheels was 68 thou. We used the Pro-Axle Press in conjunction with the Pro-Rail Rider tool to bend the axles. I used the Pro-Body Tool to "true" the axle slots and used the Pro-Axle Guide to insert the axles. I used the Pro-Wheel Shaver to "lathe" the wheels.
After construction, we attempted to align the rear wheels on a granite counter-top. The cub scout's car rear wheels would promptly go out to the axle heads. We never were able to fully tune the sibling car rear wheels to do so. The back right wheel on the sibling's car seemed to oscillate on its axle when in motion. We were able to tune both cars to turn left at a rate of 3" over 6', although the sibling car seemed much less responsive to turning the front right rear wheel axle to achieve the desired turn rate.
My observations...
1. Pro-Axle Press II/Pro-Rail Rider Tool - I didn't feel comfortable with the outcome. Despite being CNC-machined, the tools did not necessarily fit well with one another. After each moderate hammer strike, the Pro-Rail Rider Tool would recoil upwards. I'm not sure if the nail moved slightly during the process. The whole process did not seem accurate and repeatable.
2. Pro-Wheel Shaver XT II - Our pack has a rule that says the beading on the outer edge of the tire face has to remain intact. After ruining several tires, I realized that the blade of the Pro-Wheel Shaver itself was not a straight line. I'm not sure if it had been used before and repackaged or whether the blade was poorly manufactured, but the blade was rounding the tire tread near the beading. I don't think I ever truly "lathed" the inner rim of the tire that the car rode on.
I assume that the uncertainty in the bend of the axles combined with the outer edge of the wheel tread not necessarily being true were significant factors.
My questions...
1. What are better options for axle bending? The Derby Worx Pro Axle Bender appears (from watching the video) to be a more desirable option from my perspective. It seems to eliminate the uncertainty than I noted in my observations, and it appears to give more flexibility in axle angle options. Is there something I am missing? I understand there are other methods using a screwdriver, but I'd rather the certainty and repeatability of a precision tool.
2. Has anyone else observed the same issues with Pro-Wheel Shaver blades? I intend to order replacement blades for next year, but am not looking to receive the same quality blades.
3. Would it be better in the near-term to increase the respective cants on the front right wheel and the rear wheels to achieve the desired outcome, considering we were unsuccessful the first time? I assume that increasing the rear wheel cant would result in a stronger tendency to ride the axle heads, and increasing the cant on the front right wheel will allow make the the car more responsive to slight changes.
4. Also, would increasing the turn rate of the car decrease the wobble? I had read that desired turn rate was 3-5" over 8'. I used a rectangular table surface (removed the legs) as the testing board. I elevated one end with a 2'x4' and then used wood shims to make it level it in the appropriate axis.
I am happy to answer any other questions about the car construction and will appreciate any feedback. Thanks!
This thread follows my earlier post about indenting the "RR" wheel...
The good news is that my cub scout won 1st place overall in the pack. He was happy, so that's all that really matters, except that from what I observed, the car was not a rail rider, despite our attempt to do so. I stood at the end of the track and observed the car wobble on the guide rail, although not as severely as the other cars.
Two cars were built... one for my cub scout, and one for my youngest son who participated in the sibling race. I observed the same wobble in the sibling car. The sibling car also won its two heats, but the races weren't timed, and the car only ran on 2 of the 6 lanes, so I am not sure how it truly performed. Car construction was intended to be the same. Brief summary...
The front left wheel was raised. The front right wheel had a positive cant (toe in) of 1.5 deg. The body of the car near the front right wheel was indented 1/32" of an inch. Both rear wheels had a negative cant (toe out) of 2.5 deg. The spacing between the body and the front right wheel was 30 thou and the spacing on the back wheels was 68 thou. We used the Pro-Axle Press in conjunction with the Pro-Rail Rider tool to bend the axles. I used the Pro-Body Tool to "true" the axle slots and used the Pro-Axle Guide to insert the axles. I used the Pro-Wheel Shaver to "lathe" the wheels.
After construction, we attempted to align the rear wheels on a granite counter-top. The cub scout's car rear wheels would promptly go out to the axle heads. We never were able to fully tune the sibling car rear wheels to do so. The back right wheel on the sibling's car seemed to oscillate on its axle when in motion. We were able to tune both cars to turn left at a rate of 3" over 6', although the sibling car seemed much less responsive to turning the front right rear wheel axle to achieve the desired turn rate.
My observations...
1. Pro-Axle Press II/Pro-Rail Rider Tool - I didn't feel comfortable with the outcome. Despite being CNC-machined, the tools did not necessarily fit well with one another. After each moderate hammer strike, the Pro-Rail Rider Tool would recoil upwards. I'm not sure if the nail moved slightly during the process. The whole process did not seem accurate and repeatable.
2. Pro-Wheel Shaver XT II - Our pack has a rule that says the beading on the outer edge of the tire face has to remain intact. After ruining several tires, I realized that the blade of the Pro-Wheel Shaver itself was not a straight line. I'm not sure if it had been used before and repackaged or whether the blade was poorly manufactured, but the blade was rounding the tire tread near the beading. I don't think I ever truly "lathed" the inner rim of the tire that the car rode on.
I assume that the uncertainty in the bend of the axles combined with the outer edge of the wheel tread not necessarily being true were significant factors.
My questions...
1. What are better options for axle bending? The Derby Worx Pro Axle Bender appears (from watching the video) to be a more desirable option from my perspective. It seems to eliminate the uncertainty than I noted in my observations, and it appears to give more flexibility in axle angle options. Is there something I am missing? I understand there are other methods using a screwdriver, but I'd rather the certainty and repeatability of a precision tool.
2. Has anyone else observed the same issues with Pro-Wheel Shaver blades? I intend to order replacement blades for next year, but am not looking to receive the same quality blades.
3. Would it be better in the near-term to increase the respective cants on the front right wheel and the rear wheels to achieve the desired outcome, considering we were unsuccessful the first time? I assume that increasing the rear wheel cant would result in a stronger tendency to ride the axle heads, and increasing the cant on the front right wheel will allow make the the car more responsive to slight changes.
4. Also, would increasing the turn rate of the car decrease the wobble? I had read that desired turn rate was 3-5" over 8'. I used a rectangular table surface (removed the legs) as the testing board. I elevated one end with a 2'x4' and then used wood shims to make it level it in the appropriate axis.
I am happy to answer any other questions about the car construction and will appreciate any feedback. Thanks!