Pinewood Derby Wheel Prep
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- Опубліковано 8 січ 2013
- A simple, inexpensive method for truing Pinewood Derby wheels. I prefer this method because it is relatively inexpensive, is not labor intensive, it produces a good, true and concentric wheel and best of all; it's a method that your Cub Scout or other youth can do with proper supervision. Remember to ALWAYS wear safety eyewear when using power tools.
Good Luck and Good Racing!
Great how to with explanations, thank you
Good job on the video, I use a very similar process. And agree the drill press is a lot easier than the other methods I've seen.
Thanks for sharing this! I think I would like to give it a try! I like that it employs sandpaper, since that fits into the guidelines of our rules regarding wheel improvement. I also think that the other dads in our Pack would be able to get a handle on this easily.
A few questions:
- Have you tried checking the radial runout of the wheel before and after sanding to see how much improvement you get?
- Would a wooden block work for holding the sandpaper (providing it was square), or are there benefits to something with less give?
Kurt Nordstrom , the wood block should work. The only thing I would watch is warping and twisting of the wood. I do this with wet/dry sandpaper with the sandpaper wet. Water may soak up into the wood change the square edge.
I'm in the process of building a run-out gauge with an indicator and yardsticks. I saw it somewhere. It looks straight forward and effective. I'm betting some of the run-out may be from the mandrel and/or the drill press. I have checked the drill press in the video and it is negligible.
Cannie Ware Oh, another question: What speed do you run the drill press at?
Good question. I'll look when I get home. I haven't played with speed yet. Too fast you'll run the risk of distortion due to centrifugal force and possible heat buildup.
Thanks for posting this. I'm working on our first derby car. Would it be useful to draw new hashes with the Sharpie in between grits?
Travis, It wouldn't hurt anything to add hash marks between grits except with the finer grits, you'll be working longer to eliminate them. After the first pass or two of sandpaper, the wheel tread should be parallel to the bore and it should be concentric and round. The other grits are improving the wheel's finish making it smoother.
Thanks!
So, I tried this, taking readings for my wheel before and after, and I was unable to improve the concentricity. However, I measured the runout of my drill press' chuck, and was dismayed to see that it was as high as .005". This means I won't ever be able to improve a wheel beyond that, using the preess.
I may try to re-seat the chuck and see if that helps any. If this works well for you, I am going to assume you have a higher quality drill press than I do.
Kurt Nordstrom O.K. Kurt, I finally checked the speed of my drill press. It is running at 1720 rpms. I have checked my drill press before and it's run-out is negligible. Kind of surprising because my drill press is a Central Machinery (Harbor Freight) model. I'll get to building a run-out gauge and check some wheels.
Huhn, I have a CM model too, but my runout is more than negligible. Is that the original chuck, or is it an upgrade?
Can't remember. It's a keyless version. Not sure of run-out on the end product but I do know the wheels are quieter on my test board and on the track. Plus I know they're rounder. An improvement.
Cannie Ware Just curious to know if you'd had a chance to measure the run-out of the sanded wheels?
I'd like to know how you "know" they are rounder? Did you test them with a runout gauge? That's the only way you could know.
Sanding off those marks you put on them, I don't think that means they are getting any truer.
I bought a mandrel from Hobby Lobby and the mandrel screw is slightly smaller than the ID of the wheel which means the wheel wobbles slightly on the mandrel screw. Eff that. It’s worthless. Without a high precision mandrel screw, you’re better off putting the wheel stud directly into your drill chuck.
We'll just have to disagree Michael. A wheel out of round is out of round regardless if it is canted or straight. It will still be slower than a trued wheel. Lastly, we deal with wheel bores AFTER truing the wheels. Both inner and outer hubs and the bore are smoothed, polished and lubed. Also if you're careful using the mandrel, damage can be averted during insertion and extraction.
the wheel looks ;like it is wobbling in the drill press.
It may have been. They need a better mandrel. I switched over to a lathe shortly after this. I will say this technique has won many council championships. Our council is strict on wheel modifications. This technique allows helpers with basic tools and skills to compete.
Love how all these Derby car improvement videos require the use of a special tool that needs to be purchased and shipped to you. Doesn't anyone come up with ways to do this with readily available tools from the hardware store? The huge majority of us aren't building our Derby cars 2 weeks out from the race so we aren't going to be spending $100s on specialized Derby tools and don't have the time to have them shipped to us anyway. I'll just run our car with our own "home" improvements.
What about next year? You can use the tools again and again. And why wait until 2 weeks before the race? You get the kit typically months ahead of time. 5-10 minutes of surfing and researching hear and there a couple months prior will help immensely.
If you choose to wait until the last minute, then good luck I guess. This is obviously for folks who care enough and take enough time to do a better job.
And btw, this video didn't require any special tool...unless you call a little bench top drill press a "special tool". Lots of people have them, though.
If I can't remember to order the tools a month before my race then I surely won't remember to order them for next year. You don't really need these tools anyway. Just about every single thing these videos shown can be accomplished with a bit of ingenuity and tools that are readily available. Even the axle bending is easy really.
Fast cars don't have bent axles, at least in the rear. You want the holes drilled canted and use straight axles. Only the steering "Front Dominant" axle is bent.
You can't really true the wheels without a lathe. There are other methods, and none of them work.
You can polish the axles with a drill. Did it for several years.
The rest...yeah, you can do it with what you have. The main think is getting the holes drilled canted, and you need some sort of tool to do it with.
Putting that mandrill in the bore will ruin the bore and inner and outer hubs. Cant your rear axles and you don't have to worry about roundness as much. It's also faster. I recommend not doing what is shown above.
michael moore We'll just have to disagree Michael. A wheel out of round is out of round regardless if it is canted or straight. It will still be slower than a trued wheel. Lastly, we deal with wheel bores AFTER truing the wheels. Both inner and outer hubs and the bore are smoothed, polished and lubed. Also if you're careful using the mandrel, damage can be averted during insertion and extraction.
Be careful...our Pack and district made it illegal to prep the wheels in this manner AND use any wheels outside the provided standard derby kit (b/c they are made in China) despite the label claiming its BSA approved. If I followed this video, my sons car would be illegal, twice over, and disqualified. Be clear about the rules in your district!!
Yes, you are correct. Always check pack/district/Council rules before modifying a wheel. This video is a few years old now. Our current Council rules would not allow sanding/truing.
The Grand Prix wheels sold at Scout shops are the exact same as the ones in the kit, only not made in China. Made in USA. The Revell "BSA Approved" wheels and axles you can find at Lowes, Hobby Lobby, Michaels, etc....those are the ones made in China. And the wheels are heavier and less true than the USA made ones, so you wouldn't want them anyway.
And yes, some districts have stupid rules and make you use what's in the box. Yet that same District's store has all these tools and alternative parts. Just dumb.