On 7 Nov 2005 07:56:27 -0800, "tillius"
wrote:

Why would you want to weight the wheels of a Pinewood Derby car? Adding
weight at their periphery will increase the rotational inertial of the
wheels, and they will accelerate more SLOWLY than unweighted wheels. Just
the opposite of what you want. But I may be missing something...

Because the track we run on has a very long runout at the bottom of the
slope. I was thinking that the rotational inertia would cause the
wheel's RMP's to decay slower on the straight away. That, and moving
the weight from the body to the wheels would decrease the friction
between the wheel axels and the wheels.

I may be wrong, but since we've got another year to prepare, I was
thinking we could set up a small test track in the basement and try
different configurations. It would make a great science project for the
kids as well.

BTW, while I'm on the subject, is there a better lube than graphite
powder? We tried teflon and graphite this year and the graphite
definitely outperformed the teflon by a HUGE margin.

Tillman

At a bearing store I saw a spraycan of dry film lubricant based on
molebdynum disulfide, and I think it has some teflon in it as well.

I bought a can. When the stuff dries, it stays put on the metal,
doesn't come off on my fingers. It is seriously slippery stuff!

I cleaned up a 40-year-old Palmgren drillpress vise and lubed the
"ways" and screw with this stuff. WOW!!!! I put a knurled knob
on the screw in place of the little crossbar, and now I'm thinking
about putting a little spinner on the knob! I can run the vise
open and closed from end to end just by dragging my sleeve on the
knurled knob, though the vise is snug enough that there is
essentially zero wobble and play in the vise.

(This little vise is used on the bench for small things, rather than
on a drillpress)