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PINEWOOD DERBY SHOP TALK
Drilling With Accuracy

If you were reading a book and the phrase "drill bit" was used, what
mental image would you conjure up? Most people would think of a
standard high-speed steel (HSS) drill bit that is part of the drill
bit set in most people's toolbox. This type of drill bit is certainly
the most popular, but it is not the best drill bit choice for many
woodworking tasks.

Today, we will discuss the various drill bit types available for
woodworking, and how they apply to pinewood derby cars.

Regardless of the drill bit type, make sure to know the chuck size of
your drill. The chuck size determines the maximum shaft diameter of
the drill bit that can be used. Most drills today have a 1/2 inch
chuck, but there are some drills that have a 3/8 inch chuck. If your
drill has a 3/8 inch chuck, make sure to purchase bits with a shaft no
larger than 3/8 inch.

Drill Bit Types

For woodworking, you will find the following drill bit types at your
local hardware store:

Forstner - Produces a flat-bottomed, clean edged hole with no
chipping. The center point ensures that the hole is drilled where
desired. For drilling holes over 7/16 inch, Forstner Bits are
generally a better value than Brad Point bits. Some Forstner bits
have a saw tooth edge (as seen in the photo) while others do not.
Either type works well for pinewood derby use.

Forstner bits are commonly used for creating wheel wells for attaching
to the side of a pinewood derby block. They are also used for creating
holes for tungsten rounds.


Figure 1 - Forstener Drill Bit
Photo Source: www.rockler.com

Brad Point - Produces a clean edged hole will no chipping. The center
point ensures that the drill bit doesn't wander. For drilling holes
between 1/8 and 7/16 inch, Brad Point bits are usually a better value
than Forstner bits and do a better job than HSS bits.

Brad Point bits are commonly used for drilling weight holes in
pinewood derby blocks


Figure 2 - Brad Point Drill Bit
Photo Source: www.rockler.com

Auger - Produces a clean, accurate hole. The screw tip causes the bit
to "power feed", and the auger shape helps in chip removal, so this
type of bit is beneficial for drilling very deep holes.

Although Auger bits can be used for pinewood derby cars, Brad Point or
Forstner bits are usually a better choice. The screw tip on the Auger
bit is not desirable for pinewood derby cars as it makes the hole too
deep, and the power feed action can be a bit unwieldy for novice
woodworkers.


Figure 3 - Auger Drill Bit
Photo Source: www.toolbarn.com

HSS - A general purpose drill bit for use in wood, metal, plastic,
etc. Especially in larger sizes, HSS bits often chip the edge of the
hole, and can "wander". But for holes in a pinewood derby block under
1/8 inch, these are the only real choice.

To minimize chipping, keep the drill speed high, but the feed speed
low. To minimize drill bit wander, make a small dimple in the wood at
the drilling location with a nail or a punch.


Figure 4 - HSS Drill Bit
Photo Source: www.rockler.com

Spade - Also known as a "Paddle Bit" this type of inexpensive bit is
used for rough boring. Typically they are used in carpentry where a
clean hole is not necessary. I strongly recommend avoiding Spade Bits
for pinewood derby use.


Figure 5 - Spade Bit
Photo Source: www.drillspot.com

Read More at: Pinewood Derby Times Volume 9, Issue 7

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