Why do we do this???

[DerbyDad4Hire]

Quicktime brought up a good point to me. Why do we bevel the head of the axle? The new wheels are coned and we cone the performance wheels so all the bevel does is make the wheel center on the head of the axle which makes it run more unstable in my mind. Is this reasoning wrong??? I am thinking all my new axles will not have a beveled head for this reason. Any thoughts??

 

[Chief]

Sounds like a good theory...also sounds like there will be some more R&D with some posted results???

 

[Spirit Racing]

When I think thru things, I've often came up with the same question about the bevel on the axle head, when your performance wheels have a very tiny cone already. Doesn't seem needed ,and like you say may cause some instability. The only way to find out is to test and experiment. May not make any difference at all !!!! I think ya need a very consistent car to test with, maybe a DD4H "rocket" for instance

......SPIRIT.......

 

[Quicktimederby]

If anyone wants to donate a lathe I will do some testing , a lot of testing!!

 

[5KidsRacing]

Even if you beveled the head to the extreme I would never believe that the wheel gets centered on the axle head when it goes down the track. Gravity makes the wheel bore ride flat on the axle shaft and that is where you want it. What happens when your bore looses contact with the shaft and the outer hub climbs up that bevel? You are correct, you get unstable. It does that if you have bad alignment, get the wiggles, etc… then it all goes to hell. You don’t want that of course… The point at which the wheel bore/hub contacts the axle head is an important area and you need to not mess it up. My gut tells me that if you cut out the second step and make a point (sharp edge) between the bore and the hub face then you would want that area to ride on a flat surface, not a bevel. If you are running the wheels the way you cut them then I say a bevel is better.

 

[5KidsRacing]

Can I kill a thread or what!

 

[DerbyDad4Hire]

Good points...

 

[Quicktimederby]

Good points but I would still have to disagree. If the bevel comes all the way down to the O.D. of the axle the wheel is going to want to center itself, whether or not there is enough force for it to happen I don't know. But if it does even for a split second it will disrupt the alignment of the wheel as its center contact area becomes elevated. If it disturbs it enough to effect don't know. I would have to bet that a flat head with a good point on the cone of the hub would be faster and more stable. One day when I have the ability I will try. Until then, who knows?

 

[5KidsRacing]

Good points but I would still have to disagree. If the bevel comes all the way down to the O.D. of the axle the wheel is going to want to center itself, whether or not there is enough force for it to happen I don't know. But if it does even for a split second it will disrupt the alignment of the wheel as its center contact area becomes elevated. If it disturbs it enough to effect don't know. I would have to bet that a flat head with a good point on the cone of the hub would be faster and more stable. One day when I have the ability I will try. Until then, who knows?

I think we actually agree Quicktime.... if you have a sharp/point intersection between the bore and the cut out second step you would want a flat axle head. right? I agree. I agree that in that situation the wheel would like to center itself on the beveled axle head and create an unstable car. Totally agree with you...

But if you are running John's wheels and he is cutting them the same as he has in the past then that is not the situation you are in... I say in that situation I would run on a very slightly beveled axle head.

 

[Downslope]

Hell just send me th parts and I will test it......

 

[pony express]

The bevel heads on the axles only help if you are using wheels with the step still there...wheels right out of the box. I finished some tests with the step intact versus wheels with a reduced step, ie cut the step slightly smaller. There was no difference between intact full size step with a bevel axle and the reduced step with flat axles. If you use the beveled axels with the reduced step the axles head rides down into the step slope and that really slows you down. The two areas where the axle head and wheel hub meet must be flat and as small as possible.

 

[pony express]

I'd vote for no bevel. I'm sure I'd get better results on the step wheels with no bevel. Email me when they're availble.

 

[5KidsRacing]

Picture #1: Flat head axle
Picture #2: Tapered Head Axle with DD Wheel
Picture #3: What I would run with a wheel where the second step was cut out deep

 

[OTO Racing]

I agree with DD. Coned to coned i think has less point of contact = less friction. Therefore not allowing the hub to ride flat on the axle, if the wheels are canted out. (if it does in fact center itself on the axle head.) Creating a bind on the wheel = more friction on smaller point of contact. Causing more drag. These are just my thoughts coned hub is better than a beveled axle. Even a squared outer hub and a beveled axle, ( if the theory is so...... would still want to center itself ) Thus only leaving one option. Coned outer hub squared axle head.

Unless ....You have perfectly straight axles & hubs installed perfectly straight into the car. Now my thoughts are beveled to coned will work great !

 

[GravityX]

I think getting away from the bevel on the axle for the rear wheels would work, but for the DFW I think the bevel should remain. With the rear wheels we are only dealing with the negative camber (cant) angle. For the front wheel we are dealing with 3 angles; positive camber (cant), a caster angle (I'll use that term lightly) and finally the toe-in created to create steer.

Running bevel on bevel does create less point-of-contact, and in our minds less friction, but load at that point is increased because of less "bearing" available to support the load. This may have a negligible effect on our cars at this scale. Just thinking out loud here.

I do believe what others have been saying with the bevel on bevel issue, it may create instability due to the wheel and axle consistently trying to locate a "home" to rest.

The DFW is, in my way of thinking, always moving in multiple directions at once, especially through the transition and I would think trying to stabilize it against a flat surface may create more friction and potentially speed loss.

Just my two cents. Hope this all makes sense, at least it did in my head.

 

[comersj]

If unbeveled axles were available I would give them a try. Research is very interesting.

 

[AUPatrick]

It sounds like ya'll are speaking Greek to me. When I think I understand what I'm doing I see this thread and realize I have a lot to learn. Is there a Pinewood Derby For Dummies that will translate this thread?

 

[OPARENNEN]

It sounds like ya'll are speaking Greek to me. When I think I understand what I'm doing I see this thread and realize I have a lot to learn. Is there a Pinewood Derby For Dummies that will translate this thread?

On this thread, go back and look at the pics posted by 5kids.
Pic #1 shows an axel that is flat (i.e. on the bottom of the nail head) and how it toches the wheel

The darker sides of thes pics is meant to be the part of the wheel (by the bore) and how different lathe cuts on the wheel and/or the axle head, and how the two parts touch each other during the race.

The circles to the left are simply a blow-up of the touching part.