From: neidorff@uicc.com (Bob Neidorff)
Subject: Re: Making a paddle.
Originator: neidorff@makore.uicc.com
Organization: Unitrode Integrated Circuits Corp., Merrimack, NH
Date: Mon, 11 Jan 1993 14:39:49 GMT


Robert Shain recently posted that it is very hard to make a good paddle.
We can rejoice in hearing that he is wrong.  I hate to be so bold, but 
I have done it.  I made many paddles.  It is easy.  They work well.  

Many of my paddles are "Chinese Penhold".  That's what I use.

I made a few "one ply" paddles, although I personally feel that
one-ply is only good for the "Japanese Penhold" paddle shape.

I started out with a lot of research.  I sent paddles out to a lab
to study their wood.  I also studied their glues.  The wood in the
Double Happiness is basswood (latin Tilia).  The prized Hinoki is
a Japanese cedar (Chamicipress obtusa or something like that which
means FALSE cypress: it is not cypress.  Don't use cypress).  I
also looked at other paddles.  Woods tend to be similar light woods 
with high stiffness to weight.  The glue is either a common animal
glue (Double Happiness) or a urea resin (Japanese paddles).

Now I went to wood reference books to look up the physical constants
of the woods that others used.  It seems that valuable properties of
the wood in paddles is low internal friction and high rigidity to
weight.  (modulus of elasticity to density)  Cedar seems to be a good
choice there.  Also spruce.  The third parameter that came up in
discussion was "speed of sound in the wood".  I suspect that this will
have something to do with feel, but I never learned enough to say.  It
isn't commonly tabulated.  Funny coincidence: all good "guitar top" and
"piano soundboard" woods make good paddle woods!  

For my first few paddles, I bought a load of scrap guitar tops from
a guitar supply company.  I planed them flat and laminated three ply
blades from spruce and cedar.  I glued with "Plastic Resin Glue",
also called urea formaldehyde.  This is a tan powder which you mix
with water by weight.  (I did it by teaspoons.  No need to get fancy.)
Be sure to get fresh glue.  It absorbs water from the air and only
lasts a year or so on the shelf.

The three ply paddles worked well.  Thicker was faster and heavier,
as you might guess.  Balance was nice.  For the same weight and
thickness, my western red cedar paddle was faster than the double
happiness paddle.  Spruce was comparable.

When I tried to use yellow "Carpenter's Glue", the paddle came out
mushy.  I never tried contact cement or white glue, but I suspect
that they won't work well.  I also see some commercial paddles with
black glue lines.  This glue is either a resourcinol or a melamine
glue.  I never tried it because the tan glue is cheap, easy to use, 
clean, and works well.

The handle seems to be a key strength issue.  That is where paddles
flex, and that is their weak spot.  One friend showed me some paddles
he made, which he reinforced with fiberglass around the "neck".  You
can experiment with fiberglass used in repairing boats.  They also
sell a two-part epoxy to hold the cloth down.  Raw fiberglass cloth
is literally an open cloth like thin, porous burlap.  It needs epoxy
to stick it to a base.  Epoxy is foul stuff.  Wear gloves, work in
a well ventilated room, and be sure to use eye protection, just in case.

I just make the wood for the handle a bit longer than normal and glue
it on well.  I use maple, walnut, or any pretty, strong hardwood for 
handle wood.  Fiberglass is probably great, but I never bothered with it.

I haven't found a cheap source for carbon fiber.  I'd love to try it,
but it is probably as tough to use as fiberglass.

It was no fun the one time I made a maple paddle.  Slow, heavy,
bad feel, bad balance.  I guess that my research on woods pointed
me in the right direction.  Maple has all of the wrong numbers.  Yet
I had to try, just once.

After I used up the guitar top scraps, I went to the lumber yard.
You know what works great for one-ply paddles?  Suprise:

Cedar chest "Eastern Red Cedar".  The trick is to find a piece with
less than a million knots and more than 6" width.  The knots tend
to be tight, so that they don't interfere with play.  Big knots
are much worse than small ones.  Knots less than 3/4" (19mm) diameter 
are insignificant: you won't notice them in play.  Cheap.  Easy.
Light.  Fast.  Good feel.  Good balance.  Great for Japanese Penhold.

Not quite as good for Chinese penhold.  The single grain direction
makes the sweet spot sort-of skinny.  Multi-ply has a broader sweet
spot.  Sweet spot refers to the area of the paddle that is most
uniform.  A larger sweet spot allows you to play strong shots which
don't hit the center of the paddle.

I have also made Chinese penhold paddles out of 7 plies of sitka
spruce veneer.  It is tough to buy.  They will only sell it in
large quantities.  However, the paddles are very good.  I have yet
to try cedar veneer.  I can't find it.

Friends have made paddles very differently.  They buy thin hobby
plywood and THICK hobby balsawood.  They glue the plywood as top
and bottom veneer over the balsawood core.  The paddles that they
make come out light because of the balsa and fast because of the strong
plywood "skins".  The furniture industry refers to this style of
construction as a torsion box, a weak core and strong skins.
It has only one weakness: it wears out faster than a normal paddle.
However, it is cheap, easy to make, and allows you to "tune" performance
by adjusting the balsa thickness.

Happy Paddle Making!

-- 
Bob Neidorff; Unitrode I. C. Corp.  |  Internet: neidorff@uicc.com
7 Continental Blvd.                 |  Voice   : (US) 603-424-2410
Merrimack, NH  03054-0399 USA       |  FAX     : (US) 603-424-3460
Newsgroups: rec.sport.table-tennis