Rules interpretation

[drewrph1]

Hello Experts,

I am helping my nephew put together a very competitive pinewood car for his upcoming race. His pack's rules(more flexible) are quite a bit different than our local pack's rules, so I was looking for some advise. I am hoping to purchase his wheels and axles from the internet(derbydad4hire sounds good) as today is my only day off in the next 7 days and I have 6+ inches of snow to shovel outside. Please HELP! any recommendations or stores that carry what you think would work for these crazy rules is appreciated. I have highlighted questions below.

Only official Cub Scout Grand Prix Pinewood Derby Kit wheels and axles can be used. These wheels come in the kit that was provided by the Pack, or BSA official colored wheels may be used, which can be purchased at the scout store. Older version wheels are not permitted. Axles may be polished. Wheels may be lightly sanded to remove the mold projection of the tread. This light sanding of the outer edge of the wheelis the only wheel modification allowed. The tread surface of the wheel may be altered only to a flat surface that is parallel to the axle.(How can I accomplish this? sanding? rules below say wheels can be 1.15 diameter) Beveling, tapering, thin sanding, wafering or lathe-turning of the wheels is prohibited. You may drill or rout out the inside hub of the wheel.

E. Insert axles only into the grooves provided on the wood block of the car. Long wheelbase cars are not allowed. Applying wood putty in the grooves and using a drill press to make holes to insert the axles is prohibited.

F. No lathe-turned wheels or speed-axles are permitted.(How will the inspectors know if the wheels were lathed? Will lightly lathed wheels pass? Who has the best for these rules?)

G. Drill presses with mandrels or hand-held variable speed drills with mandrels in vices may be used to lightly sand wheels and polish axles. The wheel diameter may not be less than 1.150”.

H. You may file a groove in your axles to reduce friction. You may taper the inside head of each nail with a file and polish it.(Where Can I purchase good tapered, filed & polished axles? or graphite coated?) You may file down the pointed end of each nail to match the diameter of the axle. You maycut off the tapered point end of each nail and polish it. You may true-up or straighten the axles.

I. The car shall have four (4) wheels and axles; however, only three (3) wheels are required to make contact with the track. You may raise one wheel off the track surface.(Should I assume I can bend an axle?)



Do not reduce the width of the wheels. You may drill holes in the spoked area of the wheel but not the sidewall of the tires(How many holes do you recommend? What size drill bit?)

BIG Thanks for everyone's time.

Andy

 

[IAE Racing]

Good news is you can find all you supplies right here. the bad news custom build. Your wheels rules are a condurum. You can put your wheels in a drill press and "lathe" with sand paper but not a straight edge. Can "sand" them down to 1.15 but a wheel simply turned with a lathe to "square them up" can be kept as large as 1.18? Seems like you can lighten your wheels considerably!

As far as axle placement, Choices would be simply push rear axles in at a cant. =takes practice. drill into the slots with silver bullet. =moderately difficult + takes practice. Find goat boy jig. -works great for this -hard to find the fine quality jig. lastly drill holes correctly with silver bullet then cut new groove. =simple , but IMHO would slide against your rules.

 

[ngyoung]

Yeah. I was thinking the same thing. The 1.15" basically gives a huge amount of leeway for sanding down the tread. A lathed wheel is just a more precise way of achieving the same result and can leave as much as 1.18" intact. It just seems like they're allowing everyone to mod their wheels if they do it themselves and use inferior tools. You can sand wheels as well as groove axles and blunt the tips like aftermarket parts.

Drilling holes into the spokes is usually outlawed in most scouts so you don't see it too often or the rules are loose enough to also allow removing material from the inside tread which is preferred. Hopefully some of the veterans can comment on that who may have done it in the past. The problems I see introduced in doing it is imbalanced wheels and air drag but the weight reduction payoff may offset that. Ideally for weight reduction you want it all at the edge of the wheel though and leave as much as you can around the axis.

 

[Vitamin K]

Regarding the use of the slots...the ironic thing is that even the little piece of paper inside of the standard kit recommends that you check the squareness of the slots and fix with a saw if irregular. Baffles me why anybody would want to force you to use them.

If it were me, I'd go with bent axles if I couldn't drill cant. (I know I'm in the vast minority about that one, btw.) However, I've also heard you can make shims of waxed paper to angle your axles as well.

 

[Pinecarpro]

No wax paper. If you have to use the slots. Over drill the axle hole in the slot with 1/4" bit fill the slot and hole with Bondo. Sand all sides flush and clean. Then re drill with block. If axles need to be seen clean out Bondo in slot to see axles

 

[Vitamin K]

No wax paper. If you have to use the slots. Over drill the axle hole in the slot with 1/4" bit fill the slot and hole with Bondo. Sand all sides flush and clean. Then re drill with block. If axles need to be seen clean out Bondo in slot to see axles

The rules seem to specifically forbid filling and re-drilling of the slots. I think they would consider Bondo to be "wood filler."

 

[Crash Enburn]

Since you have to use the slots, move them. /images/boards/smilies/smile.gif That is, cut the block 5/8" behind the slot, and then glue the cut-off section to the other end of the block. You're still using the official, original slots, but now your rear wheels are all the way back.

Don't drill holes in the wheels. Not only is it very likely that you'll imbalance the wheels, but the wheels with holes in them are slower than the wheels without (refer to razor wheels).

"No speed axles" "You may file a groove and taper the head" I don't know what "no speed axles" is supposed to mean, then. /images/boards/smilies/confused.gif

Make the car a Rail Runner. Since you're already speaking of purchasing wheels and axles. Go with DerbyDad4Hire. Talk to John directly, and he'll make the best recommendations on which wheels to use to stay legal.

You've come to the right place!

 

[txchemist]

If you do not have time to drill and then cut a slot, or you need to drill in the existing slot, look at making the slot a tiny bit deeper to make sure your drill does NOT hit the bottom of the groove as you drill. Much less chance of a wander. Slots do vary, but make sure you have room below the axle hole.