Hub Treatment.

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
User avatar
RACER X
Merchant
Merchant
Posts: 233
Joined: Wed Jun 25, 2003 2:35 pm
Location: St. Louis
Contact:

Hub Treatment.

Post by RACER X »

We are coning our inner hub on the wheel where it contacts the body and appling an epoxy rub pad on the side of the body.

I know some rules are against conning the hubs, what are others doing.
Driver of #9 "The Shooting Star"

I would like to thank my sponsors: Dremel Tool, House of Kolor paints, Craftsman Tools, Derby Worx Pro Tools & Derby Worx Pro Wheels, Micro Finish & sand paper and 3M tape.
User avatar
Mike Parrish
Merchant
Merchant
Posts: 177
Joined: Wed Jul 09, 2003 10:22 am
Location: Northern Indiana
Contact:

Re: Hub Treatment.

Post by Mike Parrish »

We also cone our hubs. I have tried chamfering the i.d. in the past, leaving about .030/.050" land, with about the same results.

When spray painting the body we sometimes mask off an area around the axle holes about as wide as the o.d. of the hub, then we rub hobby lube onto the bare wood.
Race Fast-
Mike Parrish
Parrish Racing
www.derbydayz.com
User avatar
asatxj
Master Pine Head
Master Pine Head
Posts: 125
Joined: Thu Sep 11, 2003 5:08 am
Location: Grant MI

Re: Hub Treatment.

Post by asatxj »

We don't have any rules against coning the hubs. I write the rules so I try something "way out there" every year. This year I took one of my son's pencils apart (the lead is in a plastic holder) and used the holder as the mounting point for the axle. Very fast but doesn't stay in alignment. Next year it will be illegal as the rules committee will be adding that item to the next revision :cry: Our new rule will read something like "the hub must ride against wood or a painted surface." Axles will also have to mount into wood as we had a car made of 1/2" steel rods with wood in between them. Definitely not within the spirit of design for an Awana car.
BTW my kids cars will have coned hubs next year, after I conduct some experiments this winter.
Awana Commander
Jeep Fleet Maintenance Director
Dad
Bowhunter
I can't break the rules, I write them
!
User avatar
TurtlePowered
Master Pine Head
Master Pine Head
Posts: 344
Joined: Wed Nov 19, 2003 10:10 am
Location: Chicago, IL

Re: Hub Treatment.

Post by TurtlePowered »

Since hub coning is not allowed in our derby, we are going to try to cut a groove using a dremel around the axel slot to cut down friction that way.
User avatar
Stan Pope
Pine Head Legend
Pine Head Legend
Posts: 6856
Joined: Sat Jul 05, 2003 7:01 pm
Location: Morton, Illinois
Contact:

Re: Hub Treatment.

Post by Stan Pope »

TurtlePowered wrote:Since hub coning is not allowed in our derby, we are going to try to cut a groove using a dremel around the axel slot to cut down friction that way.
If you do it as a gentle taper into the car body as the distance from the axle increases, you should achieve the same effect as coning the hub. Of course, treat the cone of wood to minimize friction, e.g. pressing graphite onto/into the wood.

Without special tools, coning the body is somewhat more difficult than coning the hub. Both yield comparable results. Therefore, I question the desirability of rules which prevent hub coning.
Stan
"If it's not for the boys, it's for the birds!"
User avatar
TurtlePowered
Master Pine Head
Master Pine Head
Posts: 344
Joined: Wed Nov 19, 2003 10:10 am
Location: Chicago, IL

Re: Hub Treatment.

Post by TurtlePowered »

Stan Pope wrote:
TurtlePowered wrote:Since hub coning is not allowed in our derby, we are going to try to cut a groove using a dremel around the axel slot to cut down friction that way.
If you do it as a gentle taper into the car body as the distance from the axle increases, you should achieve the same effect as coning the hub. Of course, treat the cone of wood to minimize friction, e.g. pressing graphite onto/into the wood.

Without special tools, coning the body is somewhat more difficult than coning the hub. Both yield comparable results. Therefore, I question the desirability of rules which prevent hub coning.
Our rules concerning rules are not to change the shape of the wheel in any fashion. I would tend to agree rules should more specific on what should any should not be allowed. I would not want my son to attempt to lathe a wheel (if I had one) with a sharp knife but gently sanding down the edge should be very safe.

Why would you need to taper? Wouldn't just eliminating surface area around the axel area be benificial? I would think you would want around 1/8" or so of flat area around the axel then carve a half moon around the axel area. A rounded head carving bit should make a bit of a taper I would think.
User avatar
Stan Pope
Pine Head Legend
Pine Head Legend
Posts: 6856
Joined: Sat Jul 05, 2003 7:01 pm
Location: Morton, Illinois
Contact:

Re: Hub Treatment.

Post by Stan Pope »

Remember that the purpose of the taper is to cause the contact between wheel and body to happen as close as possible to the wheel's center of rotation. If you cant cone the hub, cone the body!

Since the bore is slightly larger near the inner hub face, you must also be wary of binding if the area of the car body around the axle is not flat. Thus you want a cone with a very gentle slope. 5 degrees should be plenty and not enough to cause binding in the hub.
Stan
"If it's not for the boys, it's for the birds!"
ExtremePWD
Master Pine Head
Master Pine Head
Posts: 331
Joined: Sun Nov 16, 2003 5:04 pm
Location: Illinois

Re: Hub Treatment.

Post by ExtremePWD »

Our pack rules used to be vague in that they just minimized the work on the wheels. The first year someone showed up with coned hubs there were a number of people who were upset because they just assumed it was illegal. I knew the trick but did not do it because I thought it was against the spirit of the wheel rules. I quizzed our district committee and confirmed it was legal in the district races and modified our rules to be consistent and to remove any future arguments as to the legality. My boys have been coning their hubs ever since and they are worth the effort when you're splitting seconds into thousandths or less.
User avatar
TurtlePowered
Master Pine Head
Master Pine Head
Posts: 344
Joined: Wed Nov 19, 2003 10:10 am
Location: Chicago, IL

Re: Hub Treatment.

Post by TurtlePowered »

Stan Pope wrote:Remember that the purpose of the taper is to cause the contact between wheel and body to happen as close as possible to the wheel's center of rotation. If you cant cone the hub, cone the body!

Since the bore is slightly larger near the inner hub face, you must also be wary of binding if the area of the car body around the axle is not flat. Thus you want a cone with a very gentle slope. 5 degrees should be plenty and not enough to cause binding in the hub.
So I should probably not use a cutter bit at all. Maybe a sanding wheel on a dremel would make a taper similar to that by holding in one area until you get a bit of a groove, then move to next position. Then hand sand to smooth betwen the groove marks.
User avatar
Stan Pope
Pine Head Legend
Pine Head Legend
Posts: 6856
Joined: Sat Jul 05, 2003 7:01 pm
Location: Morton, Illinois
Contact:

Re: Hub Treatment.

Post by Stan Pope »

Image

On right is cross-section of tapered hub; on left is cross-section of tapered body. I think that this is what you fed back, but here's the picture, just to be sure!

In both cases, the contact is as close as possible to the wheel's center of rotation.
Stan
"If it's not for the boys, it's for the birds!"
User avatar
Da Graphite Kid
Master Pine Head
Master Pine Head
Posts: 327
Joined: Thu Jul 03, 2003 6:29 pm
Location: Eufaula, AL.

Re: Hub Treatment.

Post by Da Graphite Kid »

Stan,
I understand what needs to be done to the body (since we can't cone the wheel hubs) but can't think of an easy way to do it.
The only one I can come up with is if we drilled pilot holes for our axles all the way through the stock block and slots. We could than set up a sanding disc at the correct angle and use a drill press to lower the disc to the desired depth. By using a drill bit or some other stiff wire, you could install it vertically below and centered on the drill press and pivot the car about the axle. This would allow the sanding disc to, in effect, pivot all around the axle hole while maintaining the same depth and angle.
Hmmm, this would all be so much easier to do if there were a tool already made that could drill the axle hole and cone the car body in one operation. Oh Randy, I smell a new custom Pro Tool in the works!
By the way, what sort of coning angle are we talking about here? Would this leave the edges of the axle hole vulnerable to easy breakage?

Da Graphite Kid
ExtremePWD
Master Pine Head
Master Pine Head
Posts: 331
Joined: Sun Nov 16, 2003 5:04 pm
Location: Illinois

Re: Hub Treatment.

Post by ExtremePWD »

One of our family car designs we developed is a minimal cross-section body from front to back. The side edges can be sanded to a wedge similar to the leading edge. Once this is done, achieving the cone effect on the body only requires creating the 5-10 degree angle along a line on either side of the axle rather than 360 degrees around a hole. This makes the job easier for the scout to perform.
User avatar
Darin McGrew
Pine Head Legend
Pine Head Legend
Posts: 1825
Joined: Fri Jul 18, 2003 1:23 pm
Location: Knoxville, TN
Contact:

Re: Hub Treatment.

Post by Darin McGrew »

Da Graphite Kid wrote:Hmmm, this would all be so much easier to do if there were a tool already made that could drill the axle hole and cone the car body in one operation.
It isn't quite what you're looking for, but I've seen a sanding bit for Dremel tools that is shaped like a cylinder with a round depression in the end. After you've drilled your axle bits, you might be able to use such a bit to remove wood from around the axle hole. You don't need to remove much wood--just enough so the wheel hub doesn't make contact with the car body anywhere except right near the axle.
User avatar
TurtlePowered
Master Pine Head
Master Pine Head
Posts: 344
Joined: Wed Nov 19, 2003 10:10 am
Location: Chicago, IL

Re: Hub Treatment.

Post by TurtlePowered »

It isn't quite what you're looking for, but I've seen a sanding bit for Dremel tools that is shaped like a cylinder with a round depression in the end.
I have not seen any sanding drum type attachments that would go on a rotary tool. Might you be talking about a tapered steel cutting bit?
User avatar
Darin McGrew
Pine Head Legend
Pine Head Legend
Posts: 1825
Joined: Fri Jul 18, 2003 1:23 pm
Location: Knoxville, TN
Contact:

Re: Hub Treatment.

Post by Darin McGrew »

darin_mcgrew wrote:It isn't quite what you're looking for, but I've seen a sanding bit for Dremel tools that is shaped like a cylinder with a round depression in the end.
TurtlePowered wrote:I have not seen any sanding drum type attachments that would go on a rotary tool. Might you be talking about a tapered steel cutting bit?
I just checked an online catalog of Dremel bits and didn't find anything. It was something like a 954 or 8175 aluminum oxide grinding stone, except it had a dimple at the end, where the 954 has a bump and the 8175 is flat.

Thinking about it, it could have been a well-worn 8175 bit that had been used as a tiny disk sander until a dimple was worn in the center of the top surface.
Post Reply