On Thu, 26 Jan 2006 22:44:54 -0600, Hugh Prescott
wrote:

Eric R Snow wrote:
On Wed, 25 Jan 2006 23:04:47 GMT, John Blinka
wrote:


Hi,

I'm in a predicament: I helped a friend a few years ago with a
small detail on a pinewood derby car he was building with his
daughter, and he won the tournament with it! That was a fluke,
but now my kid wants to race, and you can guess what her
expectations are...

Any thoughts on how to build a fast car are welcome,
but I'm mostly interested in hearing ideas about how to prepare
the wheels and axles. The kit we have to use contains 2
steel axles of about 1/8" in diameter and four plastic wheels
whose hubs are a loose fit on the axles. Interference with
the body of the car prevents the wheel from moving axially toward
the car centerline. A plastic snap ring fitting in a groove at the
outboard end of the axle prevents the wheel from falling off
in the other direction.

Rules are nebulous. I think we're expected to use the
wheels and axles from the kit and the car can't weigh more than
8 oz. And that's it. This is a low key event, and I want this
to be a father-daughter project, so I don't want to go overboard.

What I have in mind is minimizing friction through judicious
alignment and smoothing and lubrication. Any suggestions
on how to accomplish this? What sort of lubricant should I
use?

Thanks for any and all ideas.

John Blinka

Here's what I did: On the night of the big race the car still has to
be weighted. 1/4" dia lead fishing weight works well. I did not want
my son drilling the holes as the drill could pass completely through
the car and into his hand. Instead, I drilled the holes and was the
one getting the wound cleaned and stitched up. Save your child from
this outcome and let your brother drill any holes so you can watch the
race with your child.
ERS

Most decent hobby shops have Woodland Scenics Pine Car parts.

They have several different shaped weights with snap off parts to just
screw to the bottom of the pine car.

Some places have a 5 Oz weight limit.

Whatever the limit is you want the car just under the limit.

Hugh
Where's the fun in that? My son got to see first hand (so to speak)
what some of the inside of my hand looked like. He got to see fat and
connective tissue. Now that's instructive!
ERS

On Fri, 27 Jan 2006 03:07:49 GMT, John Blinka
wrote:

Rex B wrote:
Preferred lubricant seems to be dry PTFE powder.

Looks like MSC sells aerosol cans of this stuff. That's what
I'll get.

Just a heads up. Most of the aerosol PTFE's (at least the ones that
I've used) have a solvent to dilute them. This solvent has been known
to melt plastic. I've personally seen the results on a wheel and it's
not pretty.

Micropolish the axles.

I've never polished anything. What sort of abrasives are appropriate?

Fine emory cloth and finish with crocus cloth (if you can find it).


Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm