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HOME BODY DESIGN Weight Placement Friction Reduction Axel Modification Wheel Prep - Tuning

Remember : Small changes can have a dramatic impact on if you win your pinewood race or not. Friction is your enemy- Dont give it a chance! Reduce the PROBABILITY of Friction

What are you talking about Less AND more?? Reduce the Probablilty of Friction??

Friction Reduction Tips When working on your Axels The Phrase "Less is More".. is what you need - (More or Less) you really need Less surface area AND more !

Well, the axels you receive in your pinewood car kit are really not axels at all.. They are just nails as we discussed in the video section TWO Friction Reduction for your Pinewood car. And we gave you a heads up on some of their inherent drawbacks ie. inconsistent diameter, weight, manufacturing flaws. (Much more discussion and dissection on the DVD video than on this website- keep that in mind) So we must keep in several factors when trying to get the most out of your stock axels. You may think that just by polishing them, that will be good enough. Well maybe good enough for 2nd place, 3rd place but not first place. And the time to find out that polishing just isn't enough -- is not when you are taking your car off the track after the final race, and you are not the one celebrating victory. No, you would rather be the one Celebrating! So Let's take a closer look at some theorys and ways to implement them.

The classic law of friction states that friction is the product of a coefficient and a force.
Fr = u x W

Fr = the resistive force of friction, u = the coefficient of friction, and W = the weight of the object in this case the body weight of your pinewood car..

For example, it would take the same force to move a heavy table across a wooden floor if the table was on its side or if the table was on its legs, provided the coefficient of friction was the same. This is Why

 

You already know that when 2 objects rub against each other, friction is created in the form of Heat. Friction is something we want to eliminate or reduce as much as possible in pinewood racing. Once your car hits the flat track, a car with more friction will slow down quickly and other pinewood cars will pass it up before it reaches the finish line.
The Friction is caused by the roughness of the surfaces of the 2 objects, in this case the axel and the wheel. And in related but slighty different case, the wheel rubbing against the pinewood car body. It's also caused by molecular attraction between the 2 surfaces (although this is the smallest form of friction we will deal with, it stil is something to think about)

To begin with, viewed under a microscope or magnifying glass, the axes and wheels of your pinewood derby car will look--- let just say 'not very smooth'. The Rougher the 2 surfaces, the more friction.

The Slower your pinewood car will go.

You would think that there is more friction when the surfaces are larger.
But the friction law states otherwise.

It's important for Pinewood enthusiasts to know that The amount of Friction is Independent of the amount of surface areas being 'rubbed together'.
Huh? It's true, Friction is a tricky, tricky adversary! And that's one of the hundreds of Reasons why we made a Pinewood Speed Secrets DVD

 

OK, Alright! So you have 2 types of friction.. So what?? Just polish it up, add some graphite and be done with it!

Not so Fast there "Racer X" Now that you know what Friction is... Let's look at what we can do About IT.

 

There are 2 Types of Friction we are concerned with.

Static Friction= The Resistance TO motion when an object is not moving Lets think about the table again, When you first try and move it, The heavy table seems to be "glued in place" and much effort is required to overcome the inertia of this heavy object. This "Static" Friction is caused by a combination of the resistance due to the roughness of the surfaces and the molecular attractions trying to hold the surfaces together.

Kinetic Friction= Sliding Friction of a moving object Once you get the table Moving, the amount of friction is less than when it was standing still. Sliding friction is a form of kinetic friction. Most of the friction is cause by the roughness of the two surfaces.

First of all, Polishing your axels is a must - But you need to actually SEE what your doing, so I recommend you get a Magnifying glass or a 16x jewlers loop. Then, you can see the changes you are making AS you make them.

 

Wait a minute! You Just said "The amount of Friction is Independent of the amount of surface areas being 'rubbed together."

Yes I did, and that's one of those LAWS we need to 'work around !

Now that we know what friction is, and that there are two types we need to be concerned with in pinewood racing, We can examine how to reduce the friction and set our sights on KEEPING THE ENERGY instead of letting FRICTION TAKE IT AWAY! Energy you will recall, that we gained by Designing our pinewood derby body and properly weighting it, Energy you will see at work, when your pinewood car pulls away from the others on the Flat portion of the racetrack! Energy that Friction cannot get it's ugly hands on because we are going to 'outsmart it'. ok so here we go..

Once your pinewood racer hits the flat track, it can no longer gain any speed. It can only Lose speed. This Loss is due to Friction. A close look at the wheels, axels and body will allow you to understand there are several areas in which friction can influence your pinewood racer. That right, several unique areas, not just one. By looking at each area and deciding the best way to reduce the friction in that particular area, you will be helping your pinewood car to maintain it's speed during it's flat track run towards the finish line. The best way to reduce the influence of friction is to ELIMINATE IT!

I beleive you will WIN this Year !!

You see, We need to REDUCE the Probablility of Friction by ELIMINATING surface material. The Smaller the Friction surface, the Less Probability that your axel surfaces, wheel surfaces etc. will be "messing up" the friction equation with uneven surface preparation, dimensions and other irregularities. I have always figured that since the 'Coefficient of Friction - u ' (Fr = u x W) is the ONE variable which you can impact directly. It's best to concentrate on keeping that variable from 'VARYING' too much.. CRAZY you say? Maybe, But I'll let YOU be the judge... Read on..

Yet another wonderful result of friction is maximum velocity - where the drag force equals the driving force. This final, constant velocity of motion is called a "terminal velocity",

Now, we show you an inside look at how many actual friction surfaces there are and give you ways, other than just using graphite to reduce friction. Everyone will be using graphite or another lubricant so since you want the fastest car possible, you need to take it a step further.

As you can see the largest friction area is the axle shaft itself, the other area we can work on is the inner nail head. Since the axle shaft is the largest contributor to friction due to the it's surface area, The probability of irregularities varying the 'coefficient of friction' on each subsequent revolution of the wheel makes it an ideal candidate for minor (for begninner pinewood racers) or major (advanced pinewood racer) changes.

Basic Axel tips

First, look at your axles and find the small raised grooves. Now because these are ďNAILSĒ and not perfectly machined axles, they are not really round and also have all sorts of imperfections due to the process of making the nails. I go back to my Probability of Friction Theory here. There's just no way to get the Coefficent of friction constant with all that surface area But since thatís all we have to work with, You can just do the best you can. We have found that the Small raised grooves are the High Spot on the Axle. So lets get rid of those first.
These grooves must face up when you install the axles on the car. Gravity in general will be forcing the axles (which support the weight of the body) downward onto the wheels and by facing these grooves upwards, we can essentially eliminate them from the friction equation. Make sure you mark your nail head with paint to indicate where the grooves, and this oblong area is on the axle. You are doing this for future reference so when you install the axles later, you will know how to orient your axles after working on them. Now just to be sure they donít end up rubbing or throwing off your alignment File down the grooves by hand, and only file the grooves

Check your progress with a magnifying glass or a jewelers loop. You want it to be as perfect a possible. And Remember, the "other guys" are probably messing up their axels because they dont know not to do it! So when their cars wiggle and bang off the sides of the racetrack, your pinewood car will blow right past 'em!

DO NOT USE a dremel or a power tool to sand down your axels! You just need to get rid of the grooves.If you use a power tool to do this, you will remove too much of the axel material. There isnt really enough to begin with for perfect tuning of your pinewood car so if you reduce the diameter of the axle at all - You will not be able to align your car for optimum performance!.. More on that super-important subject is available on the DVD but . for now, just file the grooves smooth by hand.

Why BY HAND?

 

The INNER Nail head of each of your pinewood derby axels needs to be filed too. As you can see in the picture, there is a Pinch mark left from the nail-making process which Must be eliminated! Have an adult help you with power tools. Chuck the axle in the drill press and file down the pinched metal first flat, then the inner nail head at a 45-degree angle.. You can also use a dremel or a hand drill by mounting them in a vise and using a similar technique. Using a fine file at a 45 degree will bevel the inner nail head and reduce a particular type of friction called torque braking Ė at least on the inner nail head.

Now keep in mind that you should check your pinewood racing rules before modification of the axels or wheels. Most will allow you to debur and polish

Go slowly and again, use the jewelers loop to inspect your progress. You will be able to spot imperfections and correct them quickly. Remember the paint mark must face up when you install your axles so if you start to accidentally rub it away, repaint it.

Our Friction section combines the Basics of Friction Reduction for beginners as well as Full-on axel and wheel modification for advanced pinewood derby racers. It's definately one of the most informative documentations you will see on the subject, For Beginners and Advanced Pinewood Racers - everyone can learn something. So when you get a chance, pick up a copy of our NEW DVD..

Finally polish your pinewood axel by using the basic polishing techniques shown on the DVD. Finish up by using the CLOTH side of an EMERY sheet. Donít use the abrasive side which will change the diameter of the axel and you wont be able to align your car with enough precision to win all your pinewood races. The cloth side will buff the metal to a mirror shine. Be sure to inspect with the jewelers loupe and inspect both the inner nail head and the axle shaft.

 

Now Let's take a look at AXEL Modification ---->>>

Of course, We have a entire section devoted to Reducing Friction in your Pinewood Racer because IT's So Important! - CGI allows us to take an inside look at the wheel/ axel combination allowing you to see into the friction areas

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Areas you may overlook. Step by step you will learn how to reduce friction in your pinewood derby car and you will be able to conduct your own friction test to show the progress you have made which ultimately makes your pinewood car much faster

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