How to prepare pinewood derby car body for gluing axles in place
Before even starting the process of tuning, a builder needs to address the following. If I am drilling my own axle holes, how do I keep the axles in place? After all once I install them, I will not be able to drill through the metal.
A series of holes need to be drilled prior to painting, prior to installing the wheels and axles. It is not crucial to make them perfectly spaced, or in a perfect line. What is important is that you leave room from the edge so that the glue doe not accidentally leak on your wheels.
Pinewood derby axle glue holes
Pinewood derby axle glue holes
Graphite Wheel Channel Pinewood Derby Body
Unless you build a lot of cars, one of the problems you will quickly find out is that with drilled axle holes, there is practically no way to add graphite to the hub once you have installed the wheel and gapped them properly.
Here's a builders tip. Add a graphite lube channel. With the BSA slots, you have wood removed that allows you access the inner wheel hub. With Drilled body you literally run into a brick wall. So just add some angled channels that allow you to to get to that spot. I do mine with a rotary tool. This can easily be done withe a file or some sand paper. I just like power tools
If you accidentally take off too much and end up in the axle hole, no worries, just remember that with the BSA blocks, there is an entire slot all the way across the body. It's not going to hurt a thing.
Pinewood derby axle graphite channels
Pinewood derby axle graphite channels
What glue to use to glue Pinewood Derby axles and wheels
Super Glue or CA glue is glue of choice for many years. Just remember this stuff is super runny or liquid, a little will go a long way and I have ruined many wheel sets because of this. Little drops, I mean little. And make sure your car is nice and flat so that it does not run into the wheel. It WILL.
Expert builders are now choosing RED locktite screw thread anti-vibrate treatment. They apply it the same way as super glue. It seems that it penetrates the wood better and it literally locks the axle in place. Not going to move the tune job. So if you are out of super glue, or want to give that a try I highly reccommend it.
Derby Dust Asset Wheel
To the new to novice builder there can be great confusion in wheel choice. What does all this technical info mean? What does my Pack allows? There is no blanket BSA rule that cover all wheels. Each local PACK determines what wheels can and cannot be used.
Below is a run through of each wheel we offer with the as much info as we can provide. If you have a properly tuned car, then speed will be based mostly on wheel weight. The lighter the wheel, the faster the car. Proven concept, not mathematical.
Please take note that wheels are massed produced through injection molding system. There are too many factors to mention why each wheel is its own unique wheel as much as we want them to be the same. They are not machined from a solid mass. This just means that every wheel is different. Only one company makes the wheels, everyone else machines them to make them faster. Every company that machines wheels tries to make the sweetest lemonade they can make based on an average. There will always be outliers. If you think you have an outlier, please contact your wheel manufacturer prior to leaving feedback. I am more than positive no matter who machined your wheel they will make it right. The industry needs this leeway to continue to grow.
Derbydust.com introduced the Asset wheel to the market in 2012. We are the first to bring to the market a wheel that is hand selected to be as close to perfect as we can tell. We are the first to offer a flawless wheel hub. We saw a need to make a new wheel because of the new rules at the pack level. We asked ourselves how can we provide a better wheel if everyone has to play by the same rules. If the wheels must remain basically the same weight as factory, what can we offer to make sure you still have a leg up in the mix. We have had great results with this wheel set.
All measurements are averages and may not be actual per your specific wheel.
AWW- Average Wheel Weight
MIB- Matched Inner Bore +/- 0.0005"
OD: 1.174" Bead/Tread present (target goal may be +/- .001")
AWW: 2.56 grams ( ranges being from 2.53-2.61)
Outer Hub: 2 Step, concave head (allows reduced wheel gap)
Inner Wheel Edge: Factory
Inner Wheel Hub: Factory
Inner Hub Bore: Flawless Bores
This wheel has had the outer diameter reduced by machining with cnc lathe for a uniformed tread consistent with the alignment of the hub. Custom delrin chuck ensures no damage done to the wheel. It will have bead/tread present. Flawless Inner bores. The wheels have been sorted for any manufacturing flaws. Meet Most pack requirements. However it will not meet the 1.180" outer diameter requirement. All BSA lettering in tact.MM, MIB available.
Pinewood Derby Wheel INNER BORE
First process in determining whether or not a wheel can make this "cut" is the inner bore. We first inspect the inner bore using a digital inspection scope. Only wheels with flawless inner bores are used for this wheel set. Because of this quality control, only 2 out of 10 wheels will meet this requirement. EVEN the BIG NAMED wheels do not have this type of quality. This ensures you have the best possible wheel to start with. There is no need in doing all the following modifications if your wheel fails at this requirement.
Pictures are of wheels that did not meet our standards. Many wheels have this void straight from factory which causes unknown wheel travel, binding, and wobble. It is caused by the ejection pin from the injection molding process.
Derby Dust Asset Wheels have inner hub free of voids.
Pinewood Derby Wheel Tread
Stock Pinewood derby Wheel Tread
Machined pinewood derby wheel tread
Derby Dust Pinewood derby wheel tread
Next step is to make a uniformed, flat tread as addressed by most packs. Mold marks are removed while retaining near full tread/beaded edges. Outer wheel diameter will always be 1.170 or greater because of our machining process. Milled using CNC lathes makes the treads nearly identical to factory casting. We have a dedicated lathe for this process. The axis is fixed and never moves. What this means is that all wheels that we produce have the most consistent repeatable wheel that we can offer. There is no other way to do this. We can control all the variables By doing so, rough edges are not present on our wheel tread.
Compare the outer treads of these three wheels. First is stock, the second is the leading aftermarket seller, the last is ours. Even the most expensive aftermarket wheels have this tell-tale sign. With that in mind, we figured out a way to machine our tread to near identical to uncut wheels.
For the 2016 season, we have now improved this process by replacing the mandrel with a dedicated delrin chucking system that grabs the wheel by the inner hub. This ensures that machine work done is parallel to the hub and that any and all wheel wobble is now almost always eliminated... There is always an outlier.
This process has to be done with a cnc machine. If you try to do it by hand then you get a cut in the wheel similar to the one in the middle. It's called the "fingernail" test by the experienced judges. Run your fingernail across the wheel and if you can feel the grooves, then you know it was machined.
Pinewood Derby Wheel Go / No Inspection
To keep this wheel compliant with 99.99% of packs. We have to address the following.
We do not reduce the width of the wheel. Since most packs do not allow this modification. Most are very descriptive about this modification.
We do not "true" the edges as that changes the width of the wheel which makes it illegal according to 90% of the pack rules.
We do not modify the inner hub portion that is closest to the body. Since we do not reduce the width of the wheel, there is no need to trim this area to make it appear to have the same gap.
Pinewood derby Speed Wheel Hub
Outer hub is modified. As per most packs rules, they allow this modification by addressing it. Or do not address it as a violation of rules to modify this area.
Increased outer hub diameter. We increase the diameter of the hub by 0.0015 inches. This decreases the outer axle hub rub/friction. By opening up this area, this modification allows the wheel to travel in a more true circular motion around the axle verses an elliptical rotation. Better, more true rotation of the wheel because the head of the axle will not rub while during rotation.Outer hub is retained. Per pack rules
Beveled outer hub. This modification decreases friction (Red area in picture). We have chosen to have a wider point of contact between your axle and wheel. We feel the larger outer ring provides a more stable wheel travel when compared to just a rounded hub as most aftermarket wheels utilize. This helps the first time builders get the most speed and tuning out of their wheels. We also find that it eliminates most wheel wobble when installed on a 1.5-2 degree negative canter.
We also leave this as a 2 step hub. This allows for factory axle head depth. This also allows for proper wheel gap when using the axle tuning pliers. With a recessed rounded hub, you can no longer gap the wheel and adjust the axle with the pliers. You will have to tune your car, then push the axle in to reduce the wheel gap which can lead to undesired movement of the axle which will change your tuning work.
We also find that this type of profile allows for a larger area of graphite reserves (green area in picture). Why not store more lube for the upcoming races?
Here's the answer to the million dollar question. What do I suggest? First I say check you rules...... Then use the following advice.
So my choice: Physics car body 3-wheel racer. Lead Weight. 3k bent axles (3x 2.5, 1x 1.5), pliers, Wheel Polish kit or service, Derby Dust graphite. You will have to choose what wheels you want to play by, but they will determine speed of car second to tuning the axles correctly
Pinewood Derby Tuning is the Key
So you are going to need to focus mainly on tuning or adjusting your axles. You want your car to go down the track as straight as it can without going side to side. Easiest way to do this is 3 wheels touching and make it ride along the center strip. So you purposely make it track to the high side. Takes time. Not technical, Not complicated, just time. The correct tool-- axle pliers. This $25 purchase is the difference between a headache and a breeze. what you will need is 4x bent axles so that you can do this: for 4 wheels I always suggest 3x2.5 1x1.5 angles
If you have to do 4 wheel tuning....
Pinewood Derby Speed Axles
3k for graphite with break-in
100K for oil or graphite with just dust and spin. You are substituting the lube for a higher polish metal.
Bent axles will be fastest (rail riding) however each axle needs to be adjusted (tuned) so that it steers the car down the track and not side to side. Each axle will have to be adjusted: Watch the tuning video above...substitute treadmill for tuning board if needed. Bent axles for the wheel to ride in one spot and also change the amount of tread presented to track. Ice skates vs rollerblades just the inner part of wheel will touch. (red wheel).
Picture originally published on Derbytalk.com forum
Pinewood Derby Speed Wheels
Lighter the better. Lighter wheels will require use of tuning pliers however to remove axles/wheels.
Polish the bores. Either you or me. Its pretty simple.
Flawless bores will eliminate any abnormal rotation in relation to wheel spinning around axles.
Weight reduced wheels start around 1.7 grams. Have all the lettering. Charlie Bravo
or Black Op's
will be those weights. Charlie Bravo has factory outer tread. Black Op's will have lathed outer tread.
Derby Worx makes a 1.5 and 1 gram wheel, but a little more noticeable machining done to them. Lighter is always better! They are all very fast wheels. Choose what will meet your pack's rules.
Pinewood Derby Graphite Lube
Graphite on graphite has a lower coefficient of friction than steel on plastic. Our theory is build layers of lube on layers of lube. Then you have graphite on graphite peeling off each race. Break In / Lube building process
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There are many ways to turn that $0.02 wheel into a proven winner. We will discuss the steps in depth. Just a brief description of how PWD BSA wheels are made. Although thermoplastic vacuum is not a complicated process, understanding why wheels that come out of the same mold can vary from piece to piece is even more complicated process with variables that most don’t care to understand. The mold can be too hot, too cold, the plastic can be slightly thicker than specs or too thin. The plastic can warm for too long or not long enough. You could have a top sheet of plastic that has more water vapor than the sheet below it, etc, etc, etc. Since these wheels are massed produced, quality control is not German engineering quality. At 600,000 cub scouters per year with 4 wheels per scout you have at least 2.4 Million wheels produced each year. With 16 molds, it takes about 150,000 sheets of plastic if you did it perfectly every time. 150,000 sheets at 260 work days a year = 578 sheets a day. On a 12 hour work day it is approximately 49 sheets an hour or roughly a sheet every 75 seconds without a break! Its about numbers! Not quality!
Because of this, you could have 4 “Mold Match” wheels that roll different ways. This simple reason you could rob yourself out of a win. SMOKE AND MIRRORS
: Just because you bought 4 match wheels doesn’t mean they are exactly the same.
With that said, one has to understand that no matter how many modifications are done to the wheel, it will never be perfect. It was never designed to be perfect. It is not manufactured to be perfect. IT WILL NEVER BE PERFECT. What we try to do is make the best lemonade that we can. Before reading further, take a break. Think about this paragraph.
To increase the performance out of your wheel the following steps are how we bring performance to those factory wheels.
Step 1-is to inspect each wheel for true center. The #4 mold is the worst wheel out of the current mold. Simple visual inspection with the naked eye one can see it is off center. The wheel basically travels in an elliptical rotation. A customer made us aware of this flaw in manufacturing in Jan ’12. Since this information was brought to our attention, we no longer provide wheel sets with this mold. We simply throw it away. NO #4 molds from us. Occasionally a few other wheels are off center for unknown reasons, we simply throw them away, as well
Step #2-Ream (or simpler terms drill) the inner diameter to a consistent diameter. A reamer is a type fancy drill bit used to make exact dimensions out of pre-drilled holes. There are multiple cutting sides to a reamer so that it will leave a consistent smooth finish. At www.derbydust.com
we have determined that the best possible inner diameter is, of course, what the BSA engineers designed it to be. That is the reamer size we use. This is the first modification that we do. This is to ensure that there is no binding or friction caused by smaller than designed inner wheel diameters. This is the key to ensure you are getting the best possible speed out of your wheels. With most molds, there is no material removed with this ream, however there are a few that need it done.
Step#3 -(optional) Removing material from the inner portion of the wheel. If allowed by your pack, you can choose this modification that will lighten the wheel. Using a dedicated computer controlled lathe, we take away a small portion of inner wall thickness to lighten the wheel. This modification decreases the overall mass of the wheel, thus allowing for quicker starts. The scientific theory behind this has to do with rotational coefficient of friction. We leave the outer edge thickness as is, so that this modification only be seen to the experienced inspector. This process reduces the weight of each wheel by xxxx. Increase in speed is usually about xxxx on our test tracks when compared to factory wheels.
Step #4-The next step(optional) if chosen by you, would be to remove the outer step of the wheel hub. Once the outer step is removed, the head of it is shaped similar to a dome. By decreasing the surface area where the axle and wheel touch, you decrease friction. This modification instantly increases speeds. The tapered head of the speed axle rides on the smooth surface of domed head of the wheel. Our data shows this decreases overall times usually between .01-.015 seconds when paired with our speed axles. Most packs allow this modification. PLEASE read your rules. YOU be the judge. It is your child’s race.
Step #5- Once the head is shaped, then the wheel is chucked into a mandrel. The outer surface of the wheel is made to a consistent shape using another dedicated computer controlled lathe (we have many of these). Our dedicated machine does not change in the z axis, so our wheels theoretically should always be the same diameter. Approximately 0.005” is removed from the outer diameter of the wheel. We find this to be the necessary depth to remove not only the high spots on the wheel, but also the low spots. With the computer controlled lathe, we are able to control the rate at which the machine removes material. Because of this we can produce a wheel that is appears to be completely smooth at first inspection. It will feel smooth to finger nail test. No noticeable ridges unless you use a magnify glass. Then if you choose, we will wet sand the wheel to 1200grit smooth finish. If you pack does not allow “lathed wheels” these are the wheel set that will be “under the radar.”
We do not do any work at this time to the inner hub facing. At this time we have not found that there is much benefit to machine work at this location. Removing material at this location will also require removing material on the width of the wheel. This violates most pack rules. We offer wheels from Derby Worx that have these modifications. There is no need to “re-invent the wheel”.
We continue to gather data and with hundreds of completed cars each season, we are able to compile information that improves our process and our results.
Inner Bore Dimensions
There are 16 different molds in the NEW BSA Wheel set. Below is our data regarding this info. Measured with precision pin gauges with 0.0002" accuracy. Our mathematical calculations are based upon our best attempts at measuring data. We measured 50 wheels of each mold (800x wheels) and complied the data below. Wheels are coming along very well. Most molds are dead spot on.
Best results are wheels with the smallest average deviation and smallest bore size. View Excel Spreadsheet
MODE: The most common value in a data set.
Typical measured diameter of all wheels (TMD): 0.0970
Our favorite wheels are the #9 and #11 molds.
Precision Measured Matched Inner Bore ***New for 2013-2014 season
We believe this option is more appropriate than mold match wheels. Wheels are matched using precision certified pin gauges. Accuracy of .0002". We are the first in the industry to offer this type of service. Let's watch the rest follow. Rest assured that your wheels will be as near identical as we can make them. If all your wheels have the same rotational travel, will make it easier to tune your car and reduce wheel wobble. No need for averaging. We will match exact diameters.
With matched inner bores spun on same lathe, you have near identical wheels on the inside and out! Regardless of mold, regardless of how they cooled.
Derby Dust again challenged old thought processes! Question EVERYTHING. Take the Red Pill. It will only bring new questions!Orders your now!
Fast Pinewood Derby Speed Tricks
This is an expert build pinewood derby secret. Everyone polishes axles. Hardly anyone polishes wheels. When .001 matters, this trick makes our cars at least .01" faster every time! Want to know why that dad always finishes first? You can bet this is one of those tricks he does not share.
Nearly every once skips this step. 45 minutes of work = faster speeds as much as 0.010-0.015 seconds. So simple you cubber can do it.
Simple, no smoke and mirrors. No inflated costs. Guaranteed results.
Works with oil or dry lube. If you are using oil, skip the dry-lube prep step.
Over the 2013 summer, we did some more testing and found a way to make them a little faster. We added a pre-polish to our previous 2 step process.
You can hear and see the difference. Increases speed, decreases overall time on my track around .01-.015 seconds on 30.75 feet measuring distance. Definitely a major difference.
Included in kit:
20x micro bore no scratch buffing spears
8x no scratch cotton swabs
1x Step 1 Polishing compound
1x Step 2 Polishing Compound
1x Inner hub Dry Lube treatment
Instructions for application. Takes about 45 minutes to complete a wheel set.
Enough swabs to service 1 car.
Drill required for application
Wheels are cleaned, then polishing step 1 compound is buffed in with high speed drill and micro bore polishing spears.
Once polish is buffed, allow buffing compound to dry, then buff clean with micro bore spear.
Repeat above step for applying second step. Again allowing polishing compound to dry after application and buffing clean.
Once dry, the wheel goes through a final buffing process that makes the wheel's bore pop to a nice and shiny surface. Wheels have spun for approx 15 seconds without any lube applied. The polish is that good! And then I realized there was a missing step. I spent the summer doing some research and designed a dry lube blend used to coat the surface areas of wheel and axle rub. This lube is especially designed so that will permanently embed in the surface of the plastic wheel. It CAN"T be blown off with compressed air once buffed in! We don't sell gimmicks. I know this process yields results.
Instructions provided. Check out the YouTube