Wheels by Stan Pope

[Speedster]

Stan, I suspect you have compared the wheels you machine to that of the vendors. Do the vendors put out "Super Wheels" somehow or can wheels be duplicated by a person with the necessary equipment and practice?

[Stan Pope]

Stan, I suspect you have compared the wheels you machine to that of the vendors. Do the vendors put out "Super Wheels" somehow or can wheels be duplicated by a person with the necessary equipment and practice?

To tell you the total truth, I have not compared wheels since some Hodges Hobby House wheels 10 or so years ago. I did purchase a set of wheels from MaxV a year or so ago, but they went straight into "inspection equipment." Didn't even spin 'em!

It would make sense to compare so that I would know if I need to analyze and improve my methods, but I haven't done so.

The only feedback I've received from others was from Sporty a few years ago. IIRC, he was quite satisfied with the results from applying my method. But I should let him speak for himself, lest I pass on an inaccurate understanding.

[Speedster]

Thank you.

[sporty]

I feel and still feel the information on the tool used by stan and as far as I know, he came up with it. and he shared it with me and I made those tools to use with the lathe.

And by far, It has produced .00015 wheels run out. On average I get .001.

The blade and other things come into play. It took me many sets of wheels and Mario, gets kudos too for many sets of wheels and also to others who sent my tons of the new wheels when they first came out.

As many know I was lucky enough to get to add my comments into the new wheels before the molds were made. Still feel very blessed that some of my input came into play.

Food for thought, us long timers are not the typical scout family or parent, we have tinkered and learned and skilled to a very high level.

I strongly feel that venders who sell wheels, example, derby worx, work very hard to produce a good quality wheels. and I certainly think from the view of a stock wheel. You get a better wheel !

So, yes the tool and process stan uses to cut true his wheel or turn down is A+ in my book.


Sporty

[Stan Pope]

Thanks for affirmation, Sporty!

Sporty said, "It has produced .00015 wheels run out. On average I get .001."

Is one of these a typo? I would hope that you average much better than ".001"! "0.00015" is closer to my expectation if your lathe is tight!

[Speedster]

That is ONE phenomenal wheel at 0.00015. Do they use a 1/2" steel plate to stop the car at the end of the track?

[Stan Pope]

That is ONE phenomenal wheel at 0.00015. Do they use a 1/2" steel plate to stop the car at the end of the track?

Sadly, doing a really good job on wheel tread runout does not reduce the wheel inertia (very much) nor does it raise the starting line. So improving from 0.001" to 0.0001" radial run-out gains just a few ms. But, since at 11 mph (typical speed of a good car near the finish line) the car travels about 0.2" per millisecond, it only takes 5 ms improvement to gain an inch on the competition!

[sporty]

Thanks for affirmation, Sporty!

Sporty said, "It has produced .00015 wheels run out. On average I get .001."

Is one of these a typo? I would hope that you average much better than ".001"! "0.00015" is closer to my expectation if your lathe is tight!

No, the .001, on average, out of 10 sets of wheels. I only see 2 to 3 sets at the .00015 grade !

Many reasons why, when you get that fine into things. its easy to get the wheel on a tad wrong, the blade dulls some, not the best fit with the custom tool. I don't make a wide range of fittings into the wheel bore. I have 3 sizes I try and work with. and since the wheel bore seems to differ. I gather is is the main reason I see this.

I will note, that many stock wheels I checked out of the box were from .0015 to .002 on average.

So while Stan, may feel .001 is not the best. (because we can turn out better) .001 is still nothing to pass up either.

Yes the overall difference's don't make much of a difference on the race track when you take scout racing into account.

I think I feel where it adds up, is tight racing and on tracks, where that tiny better amount can help you. might not be much. But I seen some darn close racing over the years.

I would totally say for a novice or more standard scout racer, it should not be a major goal seeker, until if they choose to really try and perfect and go to that next level of attempting perfection on there builds.

Sporty

[Speedster]

"AN INCH IS AS GOOD AS A MILE"

Stan and Sporty, thanks for explaining things so I can understand them.
Cheers,
Bill

[Stan Pope]

Before I started reaming the bores to 0.098" dia, I would gather the wheels I would be working, sort them by bore size (outer edge), largest first, and trim down the mandrel centering pin so that each wheel, in its turn, would have a very snug fit to the alignment pin. This is difficult and time consuming, tailoring the mandrel to each wheel, and is likely part of the reason that so many of us ream the bores.

However, if I can reduce the average bore size on my car's wheels by 0.002", running 0.096" instead of 0.098", that reduces the bore friction part of my car's losses by over 2%, and 2% is huge when I'm trying to shave 2 or 3 ms out of 2500 ms run times (0.2%)!

If I understand correctly what Sporty said, he was not stepping the mandrel's centering pin down to exactly fit the next smaller bore size (as I described above), which means that some of the wheels turned had excessive "wiggle room" on the centering pin, able to move up to 0.001" or, maybe, 0.002" on the pin. Every 0.0005" error in centering the wheel on the mandrel creates 0.001" of radial run-out at the tread! And if, when honing the centering pin, I "overshoot" by 0.0005", well, there's another way to get the 0.001" of radial run-out at the tread!

Getting the mandrel centering pin "right" is non-trivial. Too big and it distorts the outer edge of the bore; too small and the run-out battle is lost! The key "measurement" on centering pin size is the force required to position the wheel on the mandrel. That force should be present so that you can barely feel the resistance when placing the wheel on the pin and pushing it flush against the mandrel face. (This amount of force would be insufficient IF the pin were "holding" the wheel while it was being turned. However, it only holds the wheel while the clamp is being placed. Then the clamp holds the wheel against the mandrel face while it is being turned!)

One more source of error is that honing the tapered centering pin to size (for me) means that the abrasive material (file, emery paper, hone) is held by hand. This introduces some risk of losing the critical "centeredness" of the pin! Again, every 0.0005" loss of "centeredness" is a 0.001" increase in tread radial run-out!

All of this sounds like it is really "fussy" and way beyond the ability of a Cub Scout. Well, yes, adapting the mandrel to each wheel in turn probably is beyond, at least for my grandsons. However, with reamed bores, they only have to get the mandrel right once (and have grandpa check their work) and then the wheel's treads can be trued nicely with typical Cub Scout dexterity!

[Stan Pope]

Background (some of the rationale for developing my mandrel / clamp process)

Like many, I have used various mandrels which held the wheel using a screw through the bore and held the wheel by pressure against the two hubs. If one is sufficiently delicate in their application of tool force and if the outer hub face is true and if the inner hub edge is true, then very satisfactory results can be obtained.

Working with youngsters, I found that most were insufficiently delicate with anything other than sandpaper. The result was typically either a ruined wheel or a broken screw. The wheel would be ruined because when tool force stopped the wheel, it would also stop the screw. But the mandrel shaft would keep turning which caused the screw to continue drawing against the wheel with ever increasing force and mashing the hub.

Sometimes the wheel would catch on the tool and the screw would bend and snap off, sending screw and wheel across the room.

So, two weaknesses in the commercially available mandrels plagued me:
1. propensity of the screw to mash the wheel or break, and
2. small (roughly 0.25") diameter upon which the holding force was applied.

In summary, the wheel was held by a small and relatively fragile part of the wheel.

A secondary concern was that the wheel was held by one of its "working surfaces", i.e. a surface which would participate in friction. I was also concerned about the trueness of the inner hub edge where one of the mandrels screws contacted. If the inner hub edge were off, then the force of the wheel against the mandrel shaft would not be balanced possibly resulting in unequal compression and resulting tilt of the bore off the rotation axis.

My last concern was the inherent run-out of the spindle and/or chuck which turned the mandrel. My drill press couldn't be relied upon to improve most of the wheels, and, as shipped, my HF mini-lathe was worse. With learning, I re-centered the lathe chuck and could recheck parts to within approx. 0.001". But that was not sufficient for the mind set I had at the time.

So design parameters included:
(1) larger diameter holding surface, with ability to apply holding force on each side without damaging the wheel
(2) minimal force applied to working parts of the hub and bore
(3) trueness of holding surface to the bore axis
(4) and, since it was apparent that re-chucking a prepared mandrel would not be an option, the replacement mandrel must be easy (and cheap) to prepare