How thin of a car is ok

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
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Duane
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Location: San Jose,CA

Re: How thin of a car is ok

Post by Duane »

PhantomVirus wrote: I made sure I had the right block with the proper grain pattern to minimize warping (heating the block in the oven probably didn't hurt either).
I wonder if baking the block is a good thing, or risky thing. Good, if it helps the car preserve its intended unwarped dimensions for a year or more. Bad, if the baking itself causes immediate warping, with no power tools available to get the block trued again before a last-day build. Here in San Jose, the humidity is moderate and steady. A Dad's car that I left unpainted wound up badly warped a year later. Its wood was light weight with moderate grain, not baked. I've baked only once. It now feels very rigid, despite being quite thin.
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sporty
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Re: How thin of a car is ok

Post by sporty »

Baking is not worth its time, not onyl can it warp the block, but once you use it, unless you seal it right away, you loose everything you were trying to do. its just gonna asborb it back.

Not to mention possibly warping some, after you built the car.

So if you cut it right away and sealed it completely, it might be okay.

Also many have tried the carbon fiber and you run into alignment issues and warping, you would have to make it, then drill or do the axles wholes after wards. You still want a full , flat surface.

So using a rod, you still need something over the surface.

Those who tried, ran into issues, and as far as I know they gave up on it. They just were not as fast as they wanted them to be.

You can easily get 8 to 10 grams for the wood alone for the cars and have no isssues. I never do have any. many others are right at that gram mark also.

Sporty
rpcarpe
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Re: How thin of a car is ok

Post by rpcarpe »

I'll cast a vote in with Sporty & Duane. Don't bake.
I tested some baking in South Carolina. Baked raw blocks from the box, baked cut cars. If left unpainted over night, the moisture (remember, South Carolina) came pretty much right back up to where it was.

I've dissuaded several build teams from baking, just by pointing out the relatively high humidity here in Alabama.
Dave Meade's a great guy, I still recommend his book but with a few warnings.
My wife started a new support group... Widows of the Pinewood Derby.
TimInOhio
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Re: How thin of a car is ok

Post by TimInOhio »

PhantomVirus wrote:If you were to go ULTRA thin could you not embed a carbon fiber rod or 2 the length of the car? Thinking of using a small dado bit on a table say to cut a single notch the length of the car then making it ultra thin (next year's project) and epoxying the carbon fiber rod into the block.....

We went pretty thin this year (0.08Cm = 1/3 inche) without issue but I made sure I had the right block with the proper grain pattern to minimize warping (heating the block in the oven probably didn't hurt either).
For what it is worth, I toyed with the idea of making an Unlimited class car with a body made entirely of carbon fiber. From my (quick) calculations, and after discussions with 2 different carbon fiber manufacturers, I did not feel that this was feasible or advantageous, so I abandoned my theory. In fact, I just went and looked at my numbers, and carbon fiber is roughly 3 times the density of pine. A car would have to be around 1/12" thick to get the weight down to that of a 1/4" pine body. Of course, someone smarter than me may figure out a way to make it work. Plus, it would look really cool! 8)
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