Pro Wheel Shaver confusion

[roosclan]

This is my boys' second year in scouting and they are wanting to improve on last year's results. They caught the PWD bug after my Tiger placed 1st in the den and 6th overall and my Wolf placed 2nd in the den and 4th overall.

To that end, I've bought the Axle Press, the Hub tool (inner & outer) and the Wheel Shaver. My confusion comes with the Wheel Shaver.

The instructions say to place the Pro Hub Tool at 1 3/16" from the base of the Shaver in order to shave the inner wheel. However, the diagram says 1 1/16" I haven't had a chance yet to mess with it (that's tomorrow), so what is the measurement supposed to be? I'd hate to show the boys the wrong way of doing it and have them mess up their wheels.

[MaxV]

The printed instructions are incorrect. The correct instructions are on our web site at:
www.maximum-velocity.com/pro-wheelxt.htm
(scroll down).

[roosclan]

That's just what I needed. Thanks!

[Sappington R]

Hey Roosclan,
Congrats on the two great finishes, but more importantly for stepping up to post on this board. You are welcome here. I am not one of the experts but am very familiar with the bsa wheels and also this tool. I bought one myself back in November, along with every other tool available from Max V.

I assume that you are confident with the tread shave application and have also seen the manufacturers video? If that is the case then I will offer the following on inner tread shaving: The purpose of inner tread shaving is to have a consistent tread width on all wheels (careful to to take to much off and violate your rules), remove any burs or imperfections, truing, and will also help with balance. What I found is that the "measurement" really didn't matter to much- we are talking about making a slight contact between the blade and the inner tread, taking very small amounts off each wheel at a time. Be careful not to dig in or you will easily scar your inner treads. I think the derbyworx instructions are pretty good but agree that the "critical measurement" doesn't really make sense- and in the end doesn't really matter so long as you get a good shave.

How much modification to the wheels does your district allow? There may be other things that you can do if it's speed that you're after.

Sappington

[roosclan]

sappingtonr said:

I assume that you are confident with the tread shave application and have also seen the manufacturers video?

Well, we haven't done it before. Last year I got the Pinewood Derby Speed Secrets book and used it to some degree for crudely polishing the axles and sanding the tread smooth. The book never mentioned the Wheel Shaver, so I didn't find out about it until right before the derby.

Be careful not to dig in or you will easily scar your inner treads. I think the derbyworx instructions are pretty good but agree that the "critical measurement" doesn't really make sense- and in the end doesn't really matter so long as you get a good shave.

We tried it this afternoon and I can tell that it will take a lot of practice (and wheels) for the boys ( 8 and almost 8) to get it right. They've already ruined one wheel each digging into the inner wheel. They didn't gouge the outer tread so far. I found it easy to set up and use, but teaching that "feel" to a child isn't so easy!

How much modification to the wheels does your district allow?

Minimal modification to the wheels. Tonight was our Blue & Gold banquet and one of the District heads was there for the FOS speech. I asked him about the rules (which haven't been diseminated to the packs yet, but are done). I mentioned that I have a couple axles that have really bad heads and a wheel that is quite out of round. He said that rounding them is ok, smoothing and polishing is ok. The wheels that come in the PWD kit must be used, so I'll have to buy another kit to get more wheels & axles. They don't want v-grooves, h-grooves, or thinner wheels (like those razor thin wheels I see for sale), but truing them and smoothing them is ok. I might try to shave some off the inside of the tread for weight reduction, since buying a pre-made set would be against the rules for District (which is the day after the pack derby). As long as tread width is the same (or very close with truing them) and the tread is flat, then I'm good to go.

There may be other things that you can do if it's speed that you're after.

I'm all ears! Steps we're adding this year:

• polish the inside bore
  
• cone the inner hub
  
• angle the axle heads
  
• 3-wheel design
  
• align the axles (didn't do that last year, and it showed with the cars bouncing back and forth)
  
• polish the axles beyond the 1500 grit we did last year
  
• put the short end of the block in the back instead of the front (another oops last year)
  
• use tungsten cubes and cylinders
  

I may take my Wolf cub's car and cut about 7/16" off the back and glue it to the front (or just leave it off). He saw the Stealth design on Max V and modified it. The real pain is getting the COG balanced properly with those tiny little tungsten cubes (I bought a Pinecar block to experiment with)! My Bear cub saw a design in the Speed Secrets book and is using that with some modification. He wants curviness on his to show off the color shifting paint we bought.

[Sappington R]

Roosclan,
That was a very well thought out comprehensive post that you just made. It sounds like you guys really have the "bug" (as do all of the others on this board- it's OK .

Just a few comments:

1. Written Rules: It sounds like the race officials are pretty laid back. I think that they should post written rules online well in advance of the race- that way all builders will be on the same page and have plenty of time to do it. If you have anything at all in writing, I wouldn't mind reading it myself- could possibly offer more suggestions, but more importantly so could the EXPERTS here, I am not one of them .

2. Scout Building: You are awesome as a father teaching your boys and letting them get as much hands on as possible. As simple as the DerbyWorx tools are, they are still difficult for an 8 year old to use. I have read where other father/scout teams let the boys do do most of the work but take more control of the "critical" steps. That's OK too!

3. Additional Speed Tips: Again, seeing the official rules would help, however, re-drilling holes vs. slots, extended WB, RRiding, to name a few.

You should also give Proxy Racing a try- great way to spend a Saturday Evening

I'm sure that some of the others will chime in here with more suggestions.

Sappington

[roosclan]

sappingtonr said:

1. Written Rules: It sounds like the race officials are pretty laid back. I think that they should post written rules online well in advance of the race- that way all builders will be on the same page and have plenty of time to do it. If you have anything at all in writing, I wouldn't mind reading it myself- could possibly offer more suggestions, but more importantly so could the EXPERTS here, I am not one of them .

They are supposed to be posted on the district website soon, and I'll definitely be getting them.

2. Scout Building: You are awesome as a father teaching your boys and letting them get as much hands on as possible.

Well, that is the whole point of PWD for scouts. The district race will have an "Outlaw" race for the dads and Boy Scouts: 8oz. limit, BSA-style wheels. Other than that, pretty much anything goes. I doubt I'll do it this year, as I just found out about it last night, but I'll start building for next year. I may enter 2 or 3. A new model Mustang hollow body, a classic Mustang hollow body, and a competitive one.

As simple as the DerbyWorx tools are, they are still difficult for an 8 year old to use. I have read where other father/scout teams let the boys do do most of the work but take more control of the "critical" steps. That's OK too!

I may have to do that. They will do all sanding and painting (with my airbrush). They seem to do OK with the axles, so I'll just hover like a hawk while they do it. I'm still a little leary about letting them work with my dremel, but I suppose I have to let go sooner or later ;D

3. Additional Speed Tips: Again, seeing the official rules would help, however, re-drilling holes vs. slots, extended WB, RRiding, to name a few.

Re-drilling holes is OK as long as they are contacting the slots (at least it was last year). Extended WB is forbidden. I may try rail riding, as it is an aluminum track.

[roosclan]

Quote:
How much modification to the wheels does your district allow?

Minimal modification to the wheels. Tonight was our Blue & Gold banquet and one of the District heads was there for the FOS speech. I asked him about the rules (which haven't been diseminated to the packs yet, but are done). I mentioned that I have a couple axles that have really bad heads and a wheel that is quite out of round. He said that rounding them is ok, smoothing and polishing is ok. The wheels that come in the PWD kit must be used, so I'll have to buy another kit to get more wheels & axles. They don't want v-grooves, h-grooves, or thinner wheels (like those razor thin wheels I see for sale), but truing them and smoothing them is ok. I might try to shave some off the inside of the tread for weight reduction, since buying a pre-made set would be against the rules for District (which is the day after the pack derby). As long as tread width is the same (or very close with truing them) and the tread is flat, then I'm good to go.

roosclan said:

sappingtonr said:

1. Written Rules: It sounds like the race officials are pretty laid back. I think that they should post written rules online well in advance of the race- that way all builders will be on the same page and have plenty of time to do it. If you have anything at all in writing, I wouldn't mind reading it myself- could possibly offer more suggestions, but more importantly so could the EXPERTS here, I am not one of them .

They are supposed to be posted on the district website soon, and I'll definitely be getting them.

Aaaaand, here they are:
mohawkdistrict.org/images/stories/Pinewood_derby_rules_district_final08.pdf

The Pertinent Parts:
Only official Cub Scout Pinewood Derby kits may be used. Any substitutions (wheels, nails, wood block, etc.) will
be disqualified. No bushings, bearing, springs, or other kit substitutes will be allowed. Kits purchased at Lowes,
Westlake etc. will be disqualified.
• The rough edges of the kit wheels may be sanded or smoothed. Wheels with grooves, treads, ridges, or other modifications will be disqualified. Oversize wheel bores will be disqualified. Wheels must retain their original shape. No rounding or other modifications will be allowed.
• The axles and wheels must be placed within the grooves provided in the stock pine block. The length between the front and rear axles cannot be changed.
• Each car must pass the inspection table before competition. The inspection team has the sole right to disqualify any car that does meet the rules. Your scout will be informed of any rule variations and will then be given the opportunity to appropriately modify his car by one or more trips to the modifications table.

According to the stuf in bold and the stuff in red, is the Wheel Shaver verboten or not? What about coning the inner hub?

[Sappington R]

Rooscloan,
I see nothing in the rules so far that would prevent you from cutting some of the block off the back and gluing it to the front "as long as the original slots and distance" is the same. That may be worth a try.

Wheel shaver? there is nothing in there prohibiting the use of a tool for "smoothing" or sanding. That's exactly what the shave does. You may reduce the overall wheel circumference slightly, but it didn't appear that they will be measuring it with a caliper- If you sand till smooth after your shaver treatment, it will be virtually undetected, and as far as I can see, not illegal.

Most of the wheel restrictions appear to be on modifications of the tread surface. When they say rounding, I'm certain that they are referring to the tread surface not the circumference.

Hub coning is such a subtle modification, very difficult to detect, however the rules do state that no other modifications can be made?? not sure on this one.

Lastly, the rules state that original BSA wheels need to be used. that is a pretty open statement. You can buy perfectly trued BSA wheels from DerbyWorx that aren't lightened- you may want to consider that. They definitely sell original BSA wheels.

One other thought- you could build two cars- one pushing the rules to the max. The other, staying conservative. If the aggressive one gets DQ'd substitute the conservative one. The rules didn't state that you can only BUILD one car. You can only race one car.

If your aggressive car is DQ'd, you can always send it in to WIRL for racing

[roosclan]

sappingtonr said:

Rooscloan,
I see nothing in the rules so far that would prevent you from cutting some of the block off the back and gluing it to the front "as long as the original slots and distance" is the same. That may be worth a try.

Already done with my Wolf's car. My Bear didn't want to try it.

Wheel shaver? there is nothing in there prohibiting the use of a tool for "smoothing" or sanding. That's exactly what the shave does. You may reduce the overall wheel circumference slightly, but it didn't appear that they will be measuring it with a caliper- If you sand till smooth after your shaver treatment, it will be virtually undetected, and as far as I can see, not illegal.

Most of the wheel restrictions appear to be on modifications of the tread surface. When they say rounding, I'm certain that they are referring to the tread surface not the circumference.

That's my thinking, too. I'm going to email the district guy anyway.

Hub coning is such a subtle modification, very difficult to detect, however the rules do state that no other modifications can be made?? not sure on this one.

Yeah, me either. It really is more of a clean up, and one could easily end up inadvertently coning the inner hub slightly if trying to sand or smooth the "rough edges of the kit wheels." In fact, I've done it when not meaning to.

Lastly, the rules state that original BSA wheels need to be used. that is a pretty open statement. You can buy perfectly trued BSA wheels from DerbyWorx that aren't lightened- you may want to consider that. They definitely sell original BSA wheels.

Yes, but they state in bold "Only official Cub scout Pinewood derby kits may be used." I suppose no one would know, but I think the idea is that father and son put the effort into perfecting the car instead of buying pre-lathed wheels and pre-polished axles. It just doesn't seem right to me considering the wording of the rules. (now the Outlaw race at district may be a different matter... )

One other thought- you could build two cars- one pushing the rules to the max. The other, staying conservative. If the aggressive one gets DQ'd substitute the conservative one. The rules didn't state that you can only BUILD one car. You can only race one car.

What I may do is have extra sets of wheels that don't have coned hubs and shaved tread and swap them if they fail inspection. I don't have time to build 4 cars at this point. The race is on April 4th and I work 10-hour days-- very limited time to work on cars before the boys' bed time.

[roosclan]

ichiban said:

Check for a rules of conduct section or somewhere where its stated that the same car from your local pack race must be used at district and only changes that make your car meet the district rules can be made.

Our pack uses the district rules for the pack rules. I doubt we have to use the exact same car, but like I said above, I don't have time to make 4 cars at this point.

Those rules of construction are very strict, I would not cone nor lighten the wheels. And using the wheel shaver I would not take the wheel diameter down much more than the smallest of the four wheels. So figure on not going below 1.180 (read with digital calipers) in wheel diameter.

Yeah, it seems pretty clear that lightening the wheels by thinning the inside is out. I'm not sure I could do it evenly anyway.

Of course, the wheels would still "retain their original shape"...

[roosclan]

Well, I just called the district head to get the low-down. He apparently didn't get the email I sent him.

He said:
If the wheel is visibly different from the naked eye, there will be a problem. It has to be visibly the same as other stock wheels.

When I asked about shaving off the high spots, he said that there would be a problem if the wheel is noticeably smaller than stock (of course a larger diameter is better anyway, right?), so I think that if I do shave the wheels, I won't be able to completely remove the mold mark.

Truing the inner tread edge = not sure. I would only be taking off just enough to even it out and then I'll sand it to have the rounded edge like the stock wheels.

coning the inner hub = bad.

lightening on the inside = bad.

At least now I know what I can teach the boys to be competitive and still stay within the letter and spirit of the rules.

[roosclan]

ichiban said:

Well hopefully the guy wont remember you when you get to the race. In the mean time re-read my post above. I would measure all four wheels and start with the smallest of them. Tru it so its the same diameter on both sides and record the diameter. Now take the other three wheels and tru them down to that diameter. Naturally I'm assuming your wheels wont be down below 1.170 and more likely around 1.180. There will be plenty of tread edge and your wheels will not be noticably trued. By chance you're called on it, I would argue in order to have a reasonable handling car all the wheels should have the same diameter and taking off 0.010 from the outside is actually a disadvantage to your cars rollout. Rollout is the distance your car travels in one rotation of the wheels.

Plus if the stock untouched wheel is close to that diameter, how can they DQ the boys' cars for having all wheels as small as a stock untouched wheel? I have a bunch so I may find the smallest ones and use those for the raised wheels, keeping them untouched in any way.