Vince Pitelka on sat 18 oct 97
I received several inquiries about the "jigs" needed to effectively make
bats from plywood or particle board. These instructions would also work for
masonite or PVC bats, but be sure and use an appropriate bandsaw blade for
each material.
These instructions are for 11 3/4"-diameter bats - the reason they are not
12" is because you will loose a little material in the saw cuts. You can
adapt the following set-up and measurements for other sizes you wish to
make. Cut the 4'x8' sheets of plywood or particle board into 12" squares.
Draw two pencil lines diagonally between corners of each piece so that they
intersect in the exact center. With the drill-press, drill a 1/16"-diameter
hole exactly on center. It is critical that this hole be drilled with a
drill-press, because the point where it comes through on the bottom must
line up perfectly with the crossed-lines on top. This hole is extremely
important in using the cutting and drilling jigs described below.
There are two jigs you will need. The first will fit on any bandsaw. Cut a
piece of 3/4" plywood or particle board 12"x24". At the mid-point along the
24" length, 12" from either end, make a single 6" bandsaw cut to the center
point of the board. Turn off the bandsaw and slide the board back off the
bandsaw blade. Holding the board with this cut away from you, measure
exactly 5 7/8" to the right of the end of the cut (the center point of the
board), and drill a 1/16" hole through the board at this point (6" from the
front and back edges of the board). Cut a piece off the sharp end of a
12-penny nail barely longer than the thickness of the board, and drive it
into the back side of this hole so that the tip of the nail sticks up about
1/8" from the top surface of the board. Slide the saw-cut back over the
bandsaw blade, and clamp the board onto the bandsaw table anywhere to the
left of the blade. If you don't have an appropriate C-clamp you can drill a
hole in the board and bolt it to the bandsaw table. It won't matter if the
head of the bolt sticks up, as long as it is at least 4" to the left of the
blade (enough to clear the corners of the 12" squares as you cut them into
circles.
Take one of your squares of plywood or particle board, and place it over
this jig to the right of the blade so that the center hole drops over the
nail-point, with one edge pressing against the bandsaw blade. Turn on the
bandsaw and start turning the board to feed the board into the blade.
Rotate the board on the center pivot until you cut a complete circle.
Repeat the process for the rest of your bats. As you can see, this
technique can be adapted to cut any size of perfect circle.
The second jig will allow you to use the drill-press to drill bat-pin holes
in the exact correct location. Measure the precise distance between the
exact centers of your bat-pins. Divide this measurement in half, and on
same jig you used on the band saw, mark a point exactly this measurement
from the tip of the nail. Center-punch this point, and on the drill-press
drill a 1/8" hole through the wood at this point. Before raising the
drill-bit out of the work, clamp the board down to the drill-press table at
a point opposite from where the nail-tip protrudes. Take one of your bats,
and with the pencil lines facing up, place the center hole securely onto the
nail-point on the jig. Along one of the cross-lines, drill a 1/8"-diameter
hole 3/8" deep (using the adjustable depth-stop on the drill-press or an
accessory depth-stop fastened onto the drill bit) exactly centered on the
line. Rotate the bat and drill another 1/8" hole along the opposite end of
the line. MAKE SURE that these holes are EXACTLY centered on the line.
Change to a drill bit that is 1/64" larger than your bat-pins (or 1/32"
larger if you are going to varnish the bats), and using the 1/8" holes as
pilot holes, drill them 3/8" deep (re-set the depth-stop) to the larger
size. Take the bat and try it on your wheelhead. If you measured carefully
and laid out everything properly it (and all subsequent ones) will fit
perfectly and rotate absolutely true. If not, figure out what you did wrong.
If the bat fits properly, put the 1/8" bit back into the drill-press and
drill the pilot holes into the rest of your bats, change to the larger bit,
and drill them all again to the larger size. Don't try to do this without
the pilot hole, because it is much harder to start a larger hole in a
precise location without a pilot hole. Try not to drill deeper than 3/8".
It really will be worth it to use a proper depth-stop.
When the bats are done, place them on the wheel one-by-one, start the wheel,
and with an electric sander put a slight bevel on the upper edge. With the
wheel still turning, press a piece of sandpaper against the beveled edge and
side of the bat.
Unless you find "Red-X" or MEDEX particle board or some equivalent, it is
absolutely essential that you thoroughly seal all surfaces of the bats with
marine spar varnish. If you are really compulsive about details, you might
want to seal the center hole with putty, but it is quite sufficient just to
assure that varnish gets in the hole. For the first coat, you may wish to
thin some of the varnish slightly with an appropriate thinner - it's an
advantage if it soaks in more. Lay out all the bats on strips of wood on
newspaper, and paint one side with spar varnish, including the bat-pin
holes, but use Q-tips or paper towel to blot any excess varnish out of the
holes right away. When dry, reverse the bats and do the other side. When
the varnish is completely dry sand lightly and give both sides a coat of
un-thinned varnish. Apply at least two more coats in similar fashion. If
you really take care to do all of this properly, the bats will last for
decades. If you don't, they'll swell up and die in a year or two.
Good luck.
- Vince
Vince Pitelka - vpitelka@DeKalb.net
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
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