Looking Good: Techniques for Finishing Your Car

Have you seen a car on the staging table that caused your jaw to drop from admiration? The paint job looks like it came right out of a custom body shop, and other details like decals and accessories look fabulous. You ask yourself: “How did they do that?”

I won’t kid you – I oftentimes ask that question as well. Clearly, some folks know how to take the finish work to a level beyond most of us. However, I can share with you some basic techniques for putting a nice finish on your car. The main tasks to be addressed are filling, sanding, priming, painting, and decal work.

Filling
It is very difficult to create a car of any intricacy without a gouge or nick that is too deep to sand out. For small defects, the simple cure is wood putty (or “Bondo” – a car body filler). Press enough of the product into the defect to completely fill the defect with some excess. If desired, you can smooth the putty with a finger dipped in tap water. Allow the putty to dry thoroughly. If the putty sinks or cracks, apply more putty and let it dry again.

For large defects (e.g., a hole drilled the wrong place), cut a piece of wood to fill as much of the defect as possible and glue it in place. After it dries fill any remaining voids with putty, and let it dry.

Next, it is time to proceed to …

Sanding
As you probably know, sanding involves smoothing the car, starting with a coarse grit paper and progressing towards a fine grit paper. A good grit progression is 60, 120, 240, and 400. This can of coarse vary, but the ultimate goal is to create a very smooth finish, free of defects and scratches.

Sanding flat surfaces is greatly simplified by using a sanding block. A sanding block is designed to hold 1/4 of a sheet of standard sandpaper. It has a padded surface which helps make the finish very smooth. When selecting a sanding block, try to find one that can be easily held by your child (not too wide or heavy).


Figure 1 – Sanding Block

For sanding concave (inward curving) shapes wrap some sandpaper around a piece of wood (or your finger). A dowel rod or a piece of broom stick works well for sanding concave curves.


Figure 2 – Concave Curves
 


Figure 3 – Convex Curves

For convex (outward curving) shapes, use a sanding block, or just hold the paper in your hand and use fingertip pressure to sand the desired area.

After the sanding is complete, remove all dust with a vacuum and/or soft rag. Then create a handle for painting. Two alternatives include:

  • Inserting a dowel rod into a weight hole
  • Inserting a long wood/dry wall screw into the bottom of the car – you might be able to insert the screw into a weight hole so that the screw hole doesn’t show, but be careful to not go all the way through the car.

Next, I recommend masking off the axle slots (if you have axle holes, then insert round toothpicks into the holes. This makes future axle insertion much easier.

Painting – Priming
Before priming, locate a place for the car to dry. We have a piece of wire strung under a shelf in the shop, with some binder clips attached to the line. When we use a screw as a paint handle, the binder clip can be clipped to the screw, allowing the car to hang upside down to dry. If you use a dowel rod as a handle, drill an appropriate sized hole in a workbench, or in a heavy piece of wood. The dowel can then be fitted into the hole while the car dries.

When spray painting, make sure to wear eye protection and a breathing mask. Then cover the hand that will hold the car with a plastic bag, secured with a rubber band. Paint in a well-ventilated, dust and wind free location. Also watch out that the over spray doesn’t get on something important (cars, walls, etc.). We have large plastic garbage cans, so we flip up the lid and use it as a backdrop for painting. Optionally, a large box can be set on end to serve as a backdrop.

The selection of the type of primer is important. I have had the most success with a “high-build” or “filler-primer”, such as that offered by “Rust-Oleum” and sold at auto parts stores. This type of primer tends to fill in the pores of the wood, minimizing the number of primer coats required. If the sanding job is done well, generally three to four coats are sufficient.

When spraying the primer, keep the can moving and apply light coats. If you go too heavy, you will get runs that must be sanded out.

Let each primer coat dry, then sand with 600 grit paper and recoat. If you find a spot that doesn’t fill in well, you can apply a little wood filler or Bondo, sand, and continue priming. Once the car body is completely smooth, you can proceed to applying the color.

Painting – Color
There are many types and brands of spray paint. I strongly recommend acrylic lacquer paint such as “Dupli-Color – Perfect Match” (auto parts store item). This type of paint dries quickly, and can be recoated at any time. Watch out for brands that “can be recoated within 1 hour or after 24 hours”. What happens if you recoat after, say, three hours? Trust me on this one, you don’t want to know.

I also suggest avoiding enamel paints. Enamel paints generally take a long time (many days) to cure, are very susceptible to finger prints, and act like a graphite magnet.

Generally two or three color coats will be sufficient. After the last coat allow the car to dry thoroughly. Then proceed to adding decals, pin striping, etc., and finally apply clear coats.

Decorations
Decorations are certainly not required, but that can really dress up a car. They also have a practical use; they can cover up any defects in the paint job. We’ll discuss dry transfer decals, stick-on decals (includes stickers) and pin-striping. All of these products are available at Maximum Velocity. .

Dry-Transfer Decals
Dry-Transfer decals are available in lots of designs, many of which are targeted at pinewood derby car builders.


Figure 4 – Dry Transfer Decal

The best dry-transfer decals are very thin and do not have a clear edge. Thus, they blend in to the paint such that you have to look closely to see that the design is actually a decal.

To apply dry-transfer decals, cut out the desired design, place it on the car in the desired location, hold it down, and use a soft pencil with a rounded tip to scribble over the entire decal (you will actually be scribbling on the transfer material, not the actual decal). After scribbling over the entire decal, carefully lift up on the transfer material. If the decal is not completely detached from the transfer material, scribble some more and try again. After the transfer material is removed, take the provided tissue-like paper and rub it over the entire decal.

Stick-on Decals
Stick-on decals, as well as stickers are also good choices. These apply much easier than dry-transfer decals, but make sure you put it where you want it. As you know, stickers like to attach themselves where you don’t want them!


Figure 5 – Sticker Decal

My daughter used stickers to decorate her Diamondbacks car; she found the stickers at a team shop. I believe that team stickers exist for every professional team, as well as most college teams.


Figure 6 – D-Backs Car
 

Home Made Stickers
Can’t find what you want, or on a budget? Make your own stickers! Find a photo, a logo, or most anything on paper. Cut it out, apply some glue, and place it on the car.

Pin Striping
I am a big fan of pin striping; it is relatively inexpensive, easy to apply, and can really dress up a car. Pin striping is long, thin, colored tape that has an adhesive backing. It adapts well to curves in the car and can be mixed and matched, both in color and in width.


Figure 8 – Yellow Pin Striping (1/4 and 1/8 inch)

To apply pin striping, unroll a piece longer than you need, pull it taut and then apply it to the car. Use a piece of tissue paper (not Kleenex, but the kind used in gift bags) to press down on the pin striping. This will eliminate any air bubbles and ensures that it is pressed down well. After the pin striping is in place, trim the excess off the ends with a sharp knife (hobby knife or razor knife). If the pin striping will be placed on the front and/or back of the car (as in Figure 7), wrap the pin striping under the car and trim it off underneath. This makes for a much cleaner finish.

Finish Coat
All decorated? Now it is time to protect your investment and give a deep glossy look. Applying multiple clear coats will not only improve the appearance, but will (mostly) protect the car from finger prints, graphite and minor scratches. Make sure to select a clear coat that is compatible with the paint you used. If you used Dupli-Color for the color, then use Dupli-Color Clear Coat. I recommend at least five coats of clear. Fortunately it dries very quickly, so you can apply the coats in a fairly short period of time.

Conclusion
I have barely covered this subject as there are certainly other options for painting and decorating your car. If you have a technique you would like to share, please send it to me, and I’ll try to include a number of reader ideas in a future article.

From Pinewood Derby Times Volume 11, Issue 5
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(C)2017, Maximum Velocity, Inc. All rights reserved.
Maximum Velocity Pinewood Derby Car Plans and Supplies

Pinewood Derby Car Showcase – March 24, 2017

Tiptoe Through the Tulips – Bob Richardson

My wife Carol wanted a car to represent a painted pony. Our church has a family wide pinewood derby race each year, so with lots of ideas flying around I found a plastic horse that would fit on the platform. She named it “Tiptoe Through the Tulips”. I drilled small holes in the three touching horse’s hooves, then anchored them to the base with sewing pins and bent them under. The car was amazingly fast and took first place in the women’s division. The wind resistance called for lots of help from 2-1/2 degree negative slanted axles, and good wheel prep. Amazingly, the center of mass is about 3/4 inch, and the car is set up for rail riding.

Batmobile – Paul Garner

This is my 9 year old son’s (Jeremy) car we built for this year’s Royal Ranger race. Our troup’s rule is you can only use the kit provided, no extra wood, action figures, etc., can be added. Other than paint, the only things that can be added are weights and decals. We are allowed to do anything to the block, axles, wheels, and axle placement as long as it’s not an added part. This batmobile is basically a modified wedge design with the thickest part of the body being 1/2 inch thick. Both axles were recessed 1/8 inch deeper into the body, and the front axle was moved back 1/2 inch to make room for the nose. The four fenders were made out of the remaining 3/4 inch of the block. Even the jet engine was made by rounding the pieces that were cut from between the fenders. I lathed the inside of the wheels to the center of the hub, then drilled the 6 holes between the spokes. My scale only registers in 1/10 ounces, and I couldn’t get a reading on the wheels after reducing their weight. They were made square and round, and the axle dowels and screws received the appropriate treatment as well. My son Jeremy picked the design, pulled the handle on the drill press for every hole and fender, did 90 percent of the sanding. He also assembled, painted and fine sanded between coats all by himself. I was very proud of the work he did. We were allowed one test run before registration to see if the car needed any adjustments. It ran 3.285 on our 32 foot aluminum track. Unfortunately, another dad picked it up off the staging table 10 minutes before the race and dropped it on the wheels. The official allowed me to look at it, but it messed up the hub of two wheels. I got it to roll straight, but it had that “bump, bump, bump, bump” on the flat spots in the hubs. Our best time was 4.015 after that, but it was still enough to take 3rd place out of 45 cars. (Editor’s Note: make it clear during registration that the cars cannot be touched once they have been turned in for registration, and have an official posted at the staging table at all times.)

Wii! – Steve Urban

Here is a picture of my 10 year old son, Kade Urban’s, 2011 Pinewood Derby Wii car, it was voted “Coolest Car” at this year’s race. record.

From Pinewood Derby Times Volume 11, Issue 4
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(C)2017, Maximum Velocity, Inc. All rights reserved.
Maximum Velocity Pinewood Derby Car Plans and Supplies

Pinewood Derby Car Showcase – March 17, 2017

Space Buggy & Flash of Night – Jim White

My grandson (Aaron Shain) and I built these two cars for his 2011 racing campaign. I hope Aaron’s hard work pays-off at the finish line.

American Flag & Ben 10 – Scott Moran

My oldest boy (Shane – 11 years old) designed the American Flag car. My youngest boy (Matthew – 8 years old) designed the Ben 10 car. Shane took 1st and Matthew took 2nd in their pack. The boys cut their cars, sanded the body, applied the wood putty, and primed and painted the cars with my airbrush equipment (the high shine comes from using PPG Deltron basecoat clearcoat). I could go on and on about the paint jobs because they did an awesome job. I have been custom painting and airbrushing for 25 years and my wife and I taught the kids to write their names with an airbrush.

Midnight – Lee Klinghoffer

This is my first foray into Pinewood Derby car-building since I was 11 — now I’m 48. I entered this in my son’s pack race in the “Open” category. It weighed in at 16.1 ounces! Everything else is stock except for the homemade speed axles. I cut 2 v-shaped grooves in them and polished to a high sheen. The car took 1st Place and a new track record.

From Pinewood Derby Times Volume 11, Issue 3
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(C)2016, Maximum Velocity, Inc. All rights reserved.
Maximum Velocity Pinewood Derby Car Plans and Supplies

Pinewood Derby Times, Volume 16, Issue 12 – March 8, 2017

PINEWOOD DERBY TIMES
Volume 16, Issue 12
March 8, 2017

In this Edition

– Editor’s Notes
– Humor

– Product Showcase – 7% off Orders of $70 or More
– Pinewood Derby Memory – Speed Prayer
– Pinewood Derby Car Showcase
– Q&A


Editor’s Notes

Last Issue of the Season
This is the last issue of the Pinewood Derby Times for the 2016-2017 season. The new issues (Volume 17) will begin in October 2017. You will automatically continue to receive the newsletter in the fall, as our mailing list will remain intact.  If your e-mail address should change before then, from the NEW e-mail account simply send a blank e-mail to: pinewood-derby-times-change@mail-list.com
with your OLD e-mail address in the ‘Subject:’ line.

We have many of the articles planned for next season, but we are always looking for your input.  So if you have an idea for an article, please send it to me at:
info@maximum-velocity.com

I would like to thank all of our readers and contributors. Your input is greatly appreciated and certainly contributes to the success of the newsletter. I wish you all a blessed summer.  See you in October.

Expanded Car Showcase
Instead of including a Feature Article, this edition contains an expanded Car Showcase.

Inventory Clearance Sale
We will be putting more items on clearance, and will have an end of season special offer in early May. At that time we will send out a short notice to our subscribers to let you know more about this sale.

New Videos from DerbyWorx
Recently DerbyWorx teamed with BSA to make a video series. Both BSA and DerbyWorx versions were made.  Here are links to the DerbyWorx version. The videos are geared towards people new to pinewood derby racing.

1. Body Prep
2. Wheel and axle prep
3. Final Assembly

MV Basic & Wedge Car Kits
If you are planning a race and are not required to use a specific kit type, our MV Basic or Wedge Car Kit are just what you need. These attractively priced kits are equipped with:

Quality Block – Unlike the blocks provided by some organizations, our blocks are soft, northwestern pine blocks, cut precisely to 7 inches long, 1-3/4 inches wide, and 1-1/4 inches tall. These dimensions, as well as the axle slots accurately duplicate the dimensions of standard pinewood derby blocks from BSA and PineCar.

Simple Axle Preparation – Don’t worry about filing off flaws, or losing hub caps. Our Speed Axles have no burrs or crimp marks, and install without hub caps. With or without polishing, they are ready to go. We supply five, so you have a spare.

Quality Wheels – Forget cheap, out of round wheels. Our MV wheels are top-quality wheels. You will not be disappointed with the quality of these wheels.

So, if your organization does not mandate a particular kit type, consider our MV Basic Car Kits or MV Wedge Car Kits.

Can We Help?
If we can help you in any way with your pinewood derby project, or if you have any feedback regarding this newsletter, please contact E-Mail Us.


Humor

Two buddies were out for a Saturday stroll. One had a Doberman and the other had a Chihuahua. As they sauntered down the street, the guy with the Doberman said to his friend, “Let’s go over to that restaurant and get something to eat.”

The guy with the Chihuahua said, “We can’t go in there. We’ve got dogs with us.”

The one with the Doberman said, “Just follow my lead.” They walked over to the restaurant and the guy with the Doberman put on a pair of dark glasses and started to walk into the restaurant.

The waiter at the door said, “Sorry, Mac, no pets allowed.”

The man with the Doberman said, “You don’t understand. This is my Seeing-Eye dog.”

The waiter said, “A Doberman pinscher?”

The man said, “Yes, they’re using them now. They’re very good.”

The waiter said, “OK then, come on in.”

The buddy with the Chihuahua figured he’d try it too so he put on a pair of dark glasses and started to walk into the restaurant. He knew his story would be a bit more unbelievable. Once again the waiter said, “Sorry, pal, no pets allowed.”

The man with the Chihuahua said, “You don’t understand. This is my Seeing-Eye dog.”

The waiter said, “A Chihuahua?”

The man with the Chihuahua said, “A Chihuahua?!? A Chihuahua?!? They gave me a Chihuahua??


Product Showcase
Last Edition Sale – 7% off Orders of $70 or More

Now is your chance to stock up before your pinewood derby event, or for next season!

Through March 21, 2016, you can get 7% off any order of $70 or more. To take advantage of this limited time offer, use coupon code MAR8NL during checkout.


Pinewood Derby Car Showcase

Vintage Jeep – Christian Hays

Back in 1977 my father and I were restoring a Ford GPW. So that was the inspiration for this car. Now I’ve got another ’42 Ford GPW that my boys and I are restoring. Crazy how you repeat things with the next generation!

Expecto Patronum – Dan Baker

Inspired by Harry Potter, this car won first place in the Tiger den and Pack races. At the district race, it won first place for all Tigers and third place overall.

1937 Bugatti & Metro Car – Pat Baldwin


I host a corporate pinewood race every year that raises money for a deserving charity. This event seems to grow bigger every year with the number of racers and supporters. There are trophies for the fastest racers, but what has become the most coveted award is the “Best in Show” trophy. This award is based on votes cast by those in attendance. Every year we are surprised at the detail and creativity that racers come up with for their cars. Here are two of the most interesting:

2015 Best of Show Winner- 1937 Bugatti
2012 Best of Show Winner- Phoenix Metro Car

The Yellow Submarine – James McAllister

For his last year as a Cub Scout my son Rich wanted a car that honored this new band he discovered called the “Beatles”. I told him they sounded familiar and that I had an idea for a car. I downloaded “The Yellow Submarine” movie for us to watch. He did most of the cutting and sanding and all of the painting himself. Funny how many Cub Scouts got it right away and how many younger parents had no idea what it was. For the record, that movie gave me nightmares as a kid!

Dawn of Justice – Dennis Pemberton

Here is the Batmobile from “Dawn of Justice”. We used the Awana block, with 1/2 inch pine for the sides. We cut out the profile and plan views, ground out side intakes, did a little sanding, then glued sections of sheet plastic to represent the armor, wings, and cockpit. Because of its color, it’s hard to see details, but the layering of plastic sheets give it a very menacing, armored look. It is very short, but there were no stability problems from the short wheelbase. The paint job got some orange peel (actually a lot of orange peel), but the judges thought it was a cool texture – it won the Design award.

Mach 5 – Jason Neufeldt



Mach 5 was entered in our 2017 Awana Grand Prix. This was Maggie’s (my daughter, 5 years old) first year racing in the Grand Prix. When my son entered Awana, I asked him if he wanted his car to look cool (design), or be fast. He said, “I want it to be super fast Dad!” So we have always gone for speed, not looks. Six years later I asked my daughter the same question/ She said, “I want it to be really cool Daddy!”  I said it may be slower than other cars honey, is that all right? She said, “That’s okay Daddy.” (So sweet). Well, it wasn’t slow. Maggie had been watching an old TV show called “Speed Racer”.  I told her it was a show that I watched as a little boy. So, she really wanted the Mach 5 as her car.

The Mach 5’s main body is the pine block, and the fenders are made out of balsa wood. The windshield is made out of a two liter Coke bottle. The cockpit is partially from a plastic model. Our goal was to make the finished car’s total weight to be 1.5 ounces, but ended up at 2.01 ounces. Then we added 1/4 inch tungsten cubes.Her car did have a mishap and flipped over and broke the back fin, and keep ramming the stop at the end. So it does have some battle wounds from the race.

She ended up beating the four year in a row Champ (her brother Luke). We were all surprised how fast her car was. To top it off, she won first place in Design and came home so proud of herself. My son was a very good sport and he had fun too.

Black Widow Velocinator – Randy Blodgett

This was the very first car my son and I built. It never lost a race, winning den, pack and district.

Green Machine, White Out, and Dirt Late Model – Adam Lamb



These are my son’s cars from this year’s race. The “Green Machine” took third place in the outlaw race, and the “White Out” car took first place in the outlaw race. The American flag wrapped “Dirt Late Model” took second in his den race.

Brick – Tomy Jones

I made a “Brick” car this year. It looks like a brick in shape and color, and feels like a brick in texture.  I wasn’t going for speed, but I won anyway, First Place Expedition Ranger Division.

Space Racer – Kelly Jones

My space racer with an alien driver has an orb with randomly flashing LEDs.  I designed, built, and embedded the circuit in transparent resin. It took first place.

Share Your Car With Our Readers

Do you have a car you would like to “show off” to our readers? If so, send us a photo of your car along with a description of any special features to:
info@maximum-velocity.com

Please include your full name. If selected, we will include the photo and description in this newsletter.

Photos must be sent by e-mail in JPG format (minimum size of 640×480, maximum size of 1280 x 960). Please shoot photos from the front left of the car, similar to the orientation of this car:

For better focus, keep the camera four or five feet away from the car, and then use the camera’s zoom to fill the frame with the car. Also, use a solid (preferably white) background for the photo.

Send only one photo per car, unless an additional photo is needed to adequately show a feature. Also, only one car per subscriber per year please. Thanks.


Pinewood Derby Memory
Speed Prayer

We were having our Royal Rangers Pinewood Derby at Roanoke Valley Cathedral of Praise and we held a Powder Puff race for the girls. One girl had a car that barely made it to the end of the track the first heat. The next time she was called to race her car she started toward the track but then knelt down, put her hands under her chin and prayed for just a few seconds. When she got up and started toward the track again she dropped her car. I was standing beside the Pastor and I told him, “That will really finish off her car now; it won’t even make it to the finish line.”

The girl picked up her car and put it on the track and when the cars were turned loose her car flew down the track beating the other three cars easily. The whole place let out a cheer so loud you would have thought the winning touchdown had just been scored in the Super Bowl! I looked over at the Pastor and said, “Well God just let me know He can, and still does answer prays fast!”

George Gobble
Roanoke, Virginia

Do you Remember?

If you have a pinewood derby story that is funny, unusual, sad, heart-warming, etc., please send it to me in an e-mail. Don’t worry about literary polish. We will edit as needed before publishing. Also, please read our submission policy.

If your story is used, you will receive a $10 coupon in May of 2017.


Q&A

Q: I was looking for any advantage I could get and was curious whether putting graphite on the tread area would help reduce the initial friction the car has to overcome. It makes sense putting it inside the hub and tread edge where it would make contact with the rail.

A: There is no benefit to putting graphite on the tread surface, but on the inner edge and inner hub of the front dominant wheel you  do want graphite. Mostly, you want to lube in the wheel bore. Fill the bore with graphite, insert the axle, spin several times, add more graphite (without removing the axle), spin some more, add graphite, spin, add, spin, etc. Do this for 5 minutes per wheel, always ending with spinning. Then put the wheels on the car and don’t add any more graphite.

For more information regarding graphite on the tread, please visit:
Pinewood Derby Times Volume 8, Issue 2.

Q: I’m trying to build the fastest PWD car that will still fit within our Pack’s rules. I already own all your polishing kits. I recently purchased your 4080 Pro-Stock wheels. Would you recommend that I do any prep work to the wheels such as smoothing the lathe marks on the outer wheel tread a bit or polishing the inner wheel bore with your pipe cleaners and wheel bore polish?

Also, several of the pinewood derby books recommend running in the wheels/axles using a Dremel and a felt wheel once the car is all built. Would you recommend this step if I’m using the Pro-Stock wheels and grooved axles, or is it likely to do more harm than good?

A: You can polish the bores with the Bore Polish, but I don’t recommend sanding the tread, as you could knock the wheels out of round.

I don’t recommend using a Dremel as it is very easy to damage the bore. Instead, I recommend lubing off of the car using the procedure described in the previous question.

Want Answers?

Do you have a pinewood derby-related question? If so, e-mail us your question.

We answer all questions by e-mail, but not every question will appear in the Q&A section of the newsletter.


Back Issues

Are you a new subscriber, or have you missed some of the previous newsletters? Don’t miss out; all of the issues for Volume 5 through Volume 16 are posted on our web site Here.

Issues from Volumes 1 to 4 are available in four formatted documents, ready for immediate download. To find out more, Click Here.


Newsletter Contributions

We welcome your contributions. If you would like to contribute an article, a web site review, a speed tip, or a pinewood derby memory, please e-mail us.

Please read our submission policy.


Subscription Information

The Pinewood Derby Times is a free e-newsletter focused on pinewood derby racing. It is published biweekly from October through March.

If you haven’t already done so, please forward this issue to your pinewood derby friends. But please don’t subscribe your friends. Let them decide for themselves. Thanks.

If this newsletter was forwarded to you, why not subscribe to receive this newsletter. There is no cost, and your e-mail address is safe, as we never sell or share our distribution list.

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You will receive a confirmation e-mail. Reply to the confirmation e-mail and you will start receiving the Pinewood Derby Times with the next issue.


Randy Davis, Editor, Pinewood Derby Times
E-Mail: mailto:info@maximum-velocity.com

(C)2016, Maximum Velocity, Inc. All rights reserved. Please do not reprint or place this newsletter on your web site without explicit permission. However, if you like this newsletter we grant permission, and encourage you to e-mail it to a friend.

Maximum Velocity disclaims any personal loss or liability caused by utilization of any information presented in this newsletter.

The Pinewood Derby Times is not specific to, and is not affiliated with the Boy Scouts of America, YMCA, Awana, or any other organization.

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Shop Talk: Drilling Small Holes – March 3, 2017

If your pinewood derby race rules allow axle holes, then you have likely drilled the holes using a drill press, or a Pro-Body Tool or Pro-Axle Jig(1) from Derby Worx. For Cub Scout axles, a #44 bit(2) is recommended, while a 3/32 inch bit is typically used for Awana axles. For a few other kits, a #43 bit works well. But regardless of the bit size, have you considered the best type of bit to use? The type of bit, as well as the technique used, both affect the accuracy of the result. In today’s shop talk we will discuss the various types of drill bits and some techniques to help improve accuracy.

Small Drill Bit Types

The most common  small drill bit types are high-speed steel (HSS), carbide, and cobalt.

HSS

HSS drill bits are flexible and strong.  They are inexpensive and used where long-term durability is not important. Most drill sets are HSS. The flexibility of the HSS bit is helpful in minimizing broken bits, but the flexibility is a hindrance where accuracy is concerned. For drilling axle holes with a Pro-Body Tool/Jig, a HSS bit is fine, as the tool minimizes the flexing of the bit; but when drilling holes with a drill press the flexibility really hinders accuracy.

Carbide

Carbide drill bits are extremely hard, so flexing is virtually eliminated. However, because they do not flex, they are prone to breakage if careful technique is not applied. Carbide bits often come with a shank larger than the bit. So if you purchase one, make sure to get one that is long enough to drill axle holes – many Carbide bits are too short for drilling axle holes.

Typical Carbide Bit

(Source:  www.carbidespecialties.com)

Cobalt

Cobalt bits(3) are also extremely hard, so flexing is virtually non-existent. But Cobalt bits have a big advantage over HSS and Carbide bits — Cobalt bits have a “split point” tip that is specifically designed to keep the bit from “wandering” (i.e., not entering the wood at the location you want).

Wood is a relatively soft medium, but it is not consistent in density. Depending on the grain, wood will change from a hard to soft density over a small fraction of an inch. This change in density affects the way the drill bit goes into the wood. The drill bit will seek to go into the softer part of the wood. With a HSS bit, the bit may wander seeking a soft spot, and then when it has entered the wood it will tend to flex away from the hard grain. This results in inaccurate holes. Carbide bits also wander, and if they wander when in a drill press, due to the rigidity of the bit either the wood will move, or the bit will break. It seems odd, but I have broken more carbide bits when drilling into wood than any other type of bit.

Cobalt bits, with their split point, are virtually wander-free.  Like other bits, once the bit enters the wood it will want to follow the softer grain, but this can be compensated for with proper drilling technique.

Cobalt Split Point vs. Typical Bit

Drilling Technique

When drilling into wood, there are three techniques that greatly improve accuracy. First, expose only the amount of the bit needed to drill the hole — leave the rest inside the drill chuck. This minimizes the opportunity of the bit to flex (or break). Second, run the drill at full speed (1,500 rpm on a drill press)(4), but enter the wood slowly. This helps to make a clean entry hole, and minimizes drill bit wander and flexing. Next, drill about half way in, pull the bit out enough to clear the debris from the drill bit flutes, and then finish the hole. The pine sap limits the ability of the flutes to clear the debris. If you don’t clear it, it can jam up, resulting in an inaccurate hole and/or an overheated bit.

Pro-Body Tool

When drilling holes with a Pro-Body Tool/Jig, make sure the tool is clamped tightly to the block and the block is clamped in place. Then, making sure that the bit is parallel to the hole in the tool, spin the drill up to speed and enter the wood slowly. Drill about halfway in, pull the drill bit back to clear the flutes, and then complete the hole.

Drill Press

When using a Drill Press, use an accurate fence to stabilize the block and set the offsite from the bottom of the block. Squeeze (or clamp) the block to the fence, then enter the wood slowly, clear the flutes at the half-way point, then complete the hole.

Final Thoughts

Drilling accurate axle holes is a challenge which can be greatly simplified by using the right equipment. When selecting equipment, the type of drill bit is one decision you don’t want to overlook.

(1) While there are other drilling guide products available, these two Derby Worx tools are the most popular tools on the market today.  You can find them Here.

(2) Drill bits are available in four size classifications.  The first class, the type in most people’s tool box, is “fractional” (1/16, 3/32, 1/4, etc). The second size class (most popular outside the US) is “metric” (1mm, 2mm, 3mm, etc). The third class is “numbered”. Numbered bits have very small increments and range from “80” (.0135 inches) to “1” (.228 inches). The #44 drill bit used for Cub Scout axles is 0.086, which is about halfway between the 5/64 and 3/32 inch fractional bits. The final drill bit class is “letter”.  These bits start after the number “1” bit and range from “A” (.234) to “Z” (.413)

(3) The #44 bits sold by Maximum Velocity are Cobalt Split-Point drill bits. You can find them Here.

(4) For Dremel type tools, run on a low to medium speed.

From Pinewood Derby Times Volume 11, Issue 2
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