In article ,
tomcas wrote:
:
:I just got finished helping my son do his Boy Scouts pinewood derby car.
: From helping other dads over the years I can tell you that the previous
osts were right on the money. If you can, true the wheels. I pushed the
:wheel on a .099 gage pin and took very light skim cuts in the Hardinge
:to true the OD to the center hole. There are ridges on the nails from
:the cold heading process on both the diameter and most importantly under
:the head (like a parting line). I skim cut these off with a thin bit in
:the Hardinge to clean up the ridges and parting line and then polished
:the OD of the nails where the wheels will contact. I don't use the saw
:slots for the nails. Instead I predrill .078 diameter holes for the
:nails in the Bridgeport to insure absolute perfect alignment. Do drill
:up to high or the car won't clear the 1/4" high track guide. The best
:lube is spray on Teflon. Do the nails and wheels but tape the ends of
:the nails so they won’t slip out of the car when you drive them in.
:Lastly, add enough weight (anywhere) so you are right at the limit. For
:the Boy Scouts that’s 5 ounces.

Add any weight near the back of the car so that the added weight starts
off higher on the ramp and gives a longer push. Shape the front of the
car so that it contacts the starting barrier as high up as possible (a
reverse wedge). The barrier rotates down to release the cars, so the
car with the highest contact point gets released first.

Furniture wax (Pledge(R), or similar) makes an excellent lubricant for
the wheels -- much better than Teflon(R). The Teflon would hold up
longer, but how many miles do you expect this thing to go?

--
Bob Nichols AT comcast.net I am "RNichols42"