Pinewood derby wheels on a wood lathe

[Paul Gilbert]

I am trying to prep the wheels and axles for my grandson's pine wood derby car. I do not have a metal lathe so to work on the nails I have had to resort to my Jacobs chuck which has .004" run out at the end of the chuck. At the exposed end of the Morris taper I have less than .001 run out.

What I am doing is to chuck up a nail and with the aid of a dial indicator get it running true to .001". Then I use a specially ground 3/16" cutter (of the metal lathe variety) in a (is it a Elsworth type holder?) That takes off the forming marks on the nail and after polishing up to micromesh a mirror smooth polish. This process is much improved over the chuck up the mail in a drill press and use a file to take off the forming marks on the nail. This process for me left me with nails that were uneven down their length and out of round to boot.

Now to the wheels. Mounting them against a smooth surface at the headstock and with a cone center in the axle bore they come stock with .012 - .015" run out. Does it seem like a proper procedure to use a negative rake scraper to get these running true? Although the smooth surface in the headstock is true, how can I be sure that the outer surface of the wheel is exactly perpendicular to the axle bore? There is a lot of slop between the axle and the wheel bore so using a nail as a centering device is not an option. Any ideas out there?

I and my grandson thank you for any advice.

 

[Robert Taylor]

I would chuck up a piece of hardwood and turn a small diameter jam chuck to hold the wheels by the center hole, They would also be perpendicular to the face of the wheel. To be legal (for pinewood derby rules) I believe you must only assist your grandson in the process. If asked he must be able to explain to the Judges how/what work was done to build the car.

 

[Peter Bergquist]

(not to be critical, but I had to bring 3 boys through Cub Scouts and the Pinewood Derby)... but I sure hope you are actually letting your grandson do that work? That's what Pinewood is for. IMHO perfectly fine if you set things up for him to be successful, but it really should be his project!

I saw far too many cars where the Cub Scout had pretty much nothing to do with building it. Those cars ended up usually being the fastest and best decorated too. Unfortunately the Scout learned very little in the skill dept.

 

[Rob Fridenberg]

Not to get too far off topic - but I was guilty of doing too much on my son's car. It is a natural thing to want to help.

I was not alone, however. One of the Dads owned a machine shop and sure enough, his sons car had a machined plate bolted to the bottom with axle retention slots allowing for precision set-up. Somehow it made it through tech. I was the guy putting the cars on the track and saw it - but I wasn't going to call the guy out.

He didn't win (in more ways than one).

 

[Matthew Ferriter]

I ran our pack's pinewood derby for many years and always encouraged parent/grandparent to stay hands-off. If I saw something that looked a little too advanced, I would ask the scout how they did it and why. If it was clear that they had little to do with the construction, they were more or less disqualified (not to their face, but an asterisk was put on the results ro evaluation later if needed). It sounds a little tough, but those were the rules and everyone were aware of the rules ahead of time. It helped keep an even playing field.

I saw one entry that was a biplane with folding wings - it was very nice. The scout had no idea how to fold or unfold them; I don't think he had ever touched the car prior to the race.

I used the opportunity to teach my sons how to use some power tools and think about reducing friction and boosting speed.

We also ran a separate parent's race for those who couldn't resist the temptation.

 

[Paul Gilbert]

This has been a grandfather/grandson project. My grandson designed the car and laid out the cut lines on the block. I cut the car out (I didn't feel safe letting a 10 year old use a band saw.) We went over all of the safety rules and the proper operation of the saw. I see this as a learning experience and a chance to get a kid growing up in a house that doesn't own an electric drill interested in wood work. He has done all the sanding and painting of the car and the polishing of the wheels and axles. I trued up the wheels and axles before the polishing, but he was there during that process.

The car design that my grandson came up with was the standard wedge shaped car body, but it had two notches cut in the right side so that it looks like a capital E. It is his "Wedge - E" car. Where he came up with that no one knows.

 

[egsiegel]

when my sons were in scouts, the pack ran a "Fathers'...anything goes" pinewood derby after the kids ran theirs.
That way we spent our time working on our cars and let the kids build their own....the way it should be.

 

[Matthew Ferriter]

We ran a parent "unlimited class" race as well. One year I built a car with a ducted fan turbine designed for an RC airplane running off two 9-volt batteries. It was pretty quick. It could also run UP the ramp and launch itself about 10 feet into the air.

I won that year - no trophy though. It probably would have won without wheels.

 

[Curt Fuller]

Here in N Utah we have a outdoor/sporting goods/you name it store that is have a full blown all ages pinewood derby in February. https://www.facebook.com/events/603931860058175/

 

[RichColvin]

Paul,

I’ve helped my grandsons my grandsons for the last few years. We use a pillar/drill press to do this. It is easy to hold the nails in the chuck and use a fine file to remove the burs. And we also hold the wheels in the chuck and use sand paper to clean any burrs off the wheel’s edge.

As many noted above, it is really important to have the boys do the work. I showed them on the 1st wheel and axle, & they did the rest (with great oversight).

It was fun helping them.

Good luck!

Kind regards,
Rich