To True or not to True, that is the question!

[RACER X]

How many out there lathe cut or true their wheels?
What method do you use? Lathe, sanding or other?
Do you sort through many wheels to find the right ones to work with?
Just looking for an idea of what everyone is doing.

Thanks

Racer X

[gpraceman]

We just do a light sanding to remove imperfections. Some wheels take a little more work than others since on Awana wheels there can be a mold mark that leaves a bit of a flat spot on the tread. I found that the more that you work the wheels, the more likely you are to mess them up.

Most rules do not allow for reshaping the wheels, so by lathing, I assume that you are just flattening the tread. Of course, there are very few people that have lathes and the skill to use it. I'm sure that even fewer of those are kids.

[MaxV]

We do lathe our Awana wheels. They are actually more true than BSA wheels, but the lathe does make sure they are round.

I set up the lathe, but my kids mount each of their wheels and turn the knobs.

[Da Graphite Kid]

Lathe cutting the wheels is specifically not allowed at Pack or District level (I imagine this is because not many have a lathe or access to one and there are safety concerns with the younger boys using one). Anyway, we sand ours to try and true them up but only after sorting through many wheels and than matching up the mold cavity numbers (stamped inside of BSA wheels). We are trying to patiently wait for some of the new tools from Max-V this year that will help this processes accuracy.

Da Graphite Kid

[MaxV]

Regarding the mold numbers, are there certain numbers that you prefer, or do you just try to find a set of 4 that match? Which mold numbers do you like the best?

[TDean]

I don't have a lathe (yet), but I have gerry-rigged one that seems to work fairly well. I put the wheel in the mandrel as usual, which goes into a drill which I have locked in a vice. Then I built a tool rest out of scrap wood which I bolted to the work bench so that it comes close to the wheel at just the right level. This works a lot better than trying to hold a file, knife or sandpaper steady when working on wheels and axels -- and gives a fair approximation of a lathe...

But, a word of caution -- like Greg and others have said, most Cub rules do not allow altering or re-shaping the tread. My son's car was almost disqualified for the District races because I had the audacity to sand the tread (VERY lightly) ALL the way around. The judge said the rules only allowed sanding on the mold mark -- before I could explain that could cause a flat spot on the wheel the guy was overruled and my son was able to race...

[Da Graphite Kid]

Randy, I can't remember for sure what wheel cavity numbers we used for sure but it seemed like #8, 11, and 15's; but we had a mix of pwd kits from the year before and had some wheels with these same cavity numbers that were discarded. I imagine that unless you buy all of the kits at once that you could get this kind od variability. We ended up using only about half the wheels we sorted through but this was due to wapage and the axle hole and not if they were trued or not.

Greg

[Barga Racing]

I engineered my own type of cutter that I bolt to the table of a drill press. I then line it up to the wheel which is monted on a mandrel using a 3-48 screw to center it. I have one of my kids run the drill press up and down while I tap the table closer. We stop and check quite a bit. We only take them down until they are cut all the way around, which takes quite alot on some wheels. Also sometimes I tap it too hard and ruin the wheel. This does seem to work pretty well. When we are done the wheels are usually round to within .001. The only problem is that I like to have all 4 wheels almost exactly the same diameter and that is had to control the depth of the cut so we usually have them to within .003. As for mold numbes it sems that 17's definitely have more meat to take off, but they are pretty bad to begin with. Also I have found 13's refairly true but the hubs on them are awful. Also I forgot to mention that we use a prohub tool first to square the hub to the centerline.

[RACER X]

If you like the Pro Hub Tool, wait until you see what is coming this fall.

We have a new/must have speed tool I think everyone is going to love!!!

[gpraceman]

If you like the Pro Hub Tool, wait until you see what is coming this fall.

We have a new/must have speed tool I think everyone is going to love!!!

If you need some of us to test these new tools out for you, just let us know.

[Stan Pope]

"Lathes" come in many shapes, sizes and configurations. Safety and machining concepts are applicable to all.

Those concepts may be taught, sometimes in very small steps, to youngsters.

The fundamental lathe concept of a workpiece rotating on a fixed axis and acted upon by a movable cutter leaves more variables than first meet the eye. Some implementations can be reached with the general purpose equipment that many of us have about our homes.

Sanding the tread of a rotating wheel is a particular lathe implementation which is specifically mentioned in the Cub Scout car kit insert. Some packs and districts interpret that mention to mean that other lathe implementations can not be used. I believe that this interpretation is incorrect.

Some groups clarify the kit insert in their own published rules to specifically exclude lathe cutting. I believe that this is overly restrictive and contrary to the underlying goals of the PWD program.

The playing field can be leveled with knowledge. Knowledge can be passed from parent to child. First, the parent must know. Some don't want to put out the effort to learn and teach, and, so, would set the rules so that we who would put out the effort are prohibited from doing so.

[Barga Racing]

Well said Stan!

[RACER X]

Stan, Thank You!!!

When we started building P.W.D. cars 3 years ago, I felt it was a great platform to not only spend time with my son, (which we do tons of anyway) It was also a great time at a young age to teach him some basic principals of physics and simple mechanics. We have had a lot of fun and will continue to have a lot of fun, but this is what gave me the spark to invent and sell the Pro Tool line for P.W.D.

We have always had access to lathes and milling machines and I am a decent hobbiest machinest, but I realized that a lot of people did not have the access os skills, thus the Pro Tool Line came about to level the playing field.

Now at 8 years old, my son understands the physics behind weight placement, why wheels need to be round and true to center and is learning about friction. Believe me, we have a lot of fun with these cars and not only do the tools help build better cars, they help teach also.

TO HECK WITH TRUEING RULES!!!! Scouts are to do their best. other wise it is just a [junk] shoot.

Racer X

[Darin McGrew]

Some groups clarify the kit insert in their own published rules to specifically exclude lathe cutting. I believe that this is overly restrictive and contrary to the underlying goals of the PWD program.

The playing field can be leveled with knowledge. Knowledge can be passed from parent to child. First, the parent must know. Some don't want to put out the effort to learn and teach, and, so, would set the rules so that we who would put out the effort are prohibited from doing so.

That's the basic attitude we try to follow in our derbies. Rather than prohibit a technique, we try to make it accessible to everyone. We try to provide information that will help everyone build a better derby car, and at our workshops we try to provide tools, supervision, and support that will help everyone build a better derby car.

But at some point, you move away from building a better derby car, and you start building something that is fundamentally different (but which happens to fit the same track as a derby car). That's where we try to draw the line. Thus, our derby allows the removal of manufacturing irregularities, but does not allow the wheels to be reshaped. There's a difference between truing the original wheels and engineering new wheels using the original wheels as raw material. We want to allow the former, while prohibiting the latter.

[Stan Pope]

But at some point, you move away from building a better derby car, and you start building something that is fundamentally different (but which happens to fit the same track as a derby car). That's where we try to draw the line. Thus, our derby allows the removal of manufacturing irregularities, but does not allow the wheels to be reshaped. There's a difference between truing the original wheels and engineering new wheels using the original wheels as raw material. We want to allow the former, while prohibiting the latter.

Hello, again, Darin

Good points!

Our district agrees ... worked wheels must have a tread that is flat in cross-section and only limited material may be removed. At least traces of the outer corner tread marks must remain, detectable by sight or feel. If the wheels appear to deviate from cylindrical tread, then the wheel tread must rest squarely on the track. There are some other limitations on mass removal, too, that I won't go into. (It's all in the Wotamalo District website, anyway. Organization of the rules isn't too great, but I've only got one 'open door' awaiting closure. And, maybe this year the chairman will give me enough time to renumber everthing. Just too many cross-references!)

I think that this approach allows deviations that would be expected in a cub-built car but avoids deliberate manipulations that could lead to a "vertical-plane knife-edge".