After letting the lacquer cure for a few days, the front
of the fixed backer and the back of the L-Fence assembly gets wet sanded
starting with an 8,000 grit pad and ending with a 12,000 grit pad. When that’s done the masking tape is
removed and the surfaces get waxed to make them as slippery as possible to make
adjusting the jig easy. The back of the
fixed backer and the front of the L-fence assembly gets just the 8,000 grit
sanding since I don’t need as slick and polished surfaces as the previous faces
since these won’t be sliding against anything.
Once the wet sanding is done the handle gets screwed back onto face of
the assembly. The photo shows the gray
8,000 grit wet sanding pad. It’s
attached to an MDF block using the hook and loop system.
The carriage bolts that clamp the adjustable L-fence to
the fixed backer ended up needing to be 2¾” long. I can buy either 2½” or 3” long ones but not
2¾” ones. Cutting them off is not much of a problem. First, the bolt is
securely attached to a block using a ¼”-20 die as a nut. Second, is to wrap the end of the bolt in
masking tape and mark the cut location.
I use masking tape so it’s easy to see where to make the cut and to give
the blade something grab onto when starting the cut. If there are a lot of pieces needed a jig saw
with a metal cutting blade would be used.
However, here with only two to cut I use a hacksaw. When the die gets removed it cleans up the
threads that were damaged when cutting.
That’s followed by grinding the cut end smooth and last using a fine
file to knock off any remaining sharp edges.
Reinstalling the “T” nuts in the fixed backer is
next. A socket and C-clamp are used to
do that. The socket is used because
the “T” nut gets pressed in just below the plywood’s surface so something
smaller than the outer diameter of the “T” nut is needed. The other clamp is holding a piece of plywood
in place to keep the C-clamp from marring the lacquer finish.
The last bit of work is to glue the carriage bolts in the
knobs. That can be done with either
epoxy or super glue. In this case I used
a couple drops of super glue. With that
done the jig can be assembled and put to use.
Here it is attached and ready to go.
One big use of the fence is to replace the sacrificial fence when cutting tenons or making rabbits. As I said in the first post the usual method
is to clamp a scrap piece of plywood or in this case a piece of old countertop to the table saw rip fence and bury a part
of the dado blade in it. The problem
with this method is the sacrificial fence gets chewed up as dados get cut and
it has to be replaced.
For example, to make a 3/16” wide rabbit, ¼” deep using
the L-fence a series of dado blades are stacked up on the table saw wider than 3/16” . The table saw is then set for a ¼”
deep cut. Next, the L-fence is set so
the bottom of the adjustable part clears the top of the dado stack to keep it
from being cut. Last, the saw’s rip
fence is set so 3/16” of the dado stack is exposed. The lower left drawing below shows that all
done. The top photo shows the jig on the
saw with the setup complete and after the cut is made. For clarity the table saw’s miter fence has been pulled back out of the way. The bottom
right photo is a close in view of the cut showing what the first tenon cut
looks like. In this example the dado
stack at 5/8” wide is way bigger than needed but is does not matter since
what’s under the L-fence is out in the open.
This is an advantage as it eliminates the time needed to add or subtract
dado blades if there are several cuts of varying widths since you can stack the
blades for the widest cut and use the L-fence to set the width.
Another use of the jig is to put a straight edge on a
piece whose edge is bad or needs to be cut not parallel to an existing
edge. Examples include getting rid of
irregular sap wood on an edge or cleaning up an edge when neither side has a
good edge to work from or the piece is too small to use the jointer. It could also be
used if you wanted to align a new edge to the existing grain if it’s running at
an angle or cut a taper. This process
starts by taking a known straight piece and using double face tape stick it
just about 1/32” offset from the final cut.
The top photo shows a piece of 1½” thick walnut with a rough edge whose
opposite edge is not straight either.
The bottom photo is a closer view of the left end.
Next is to raise the adjustable part of the L-fence so
the face of the tapered edge is near the top of the straight edge piece that’s
attached to the walnut. The saw blade is
raised enough to cut through the walnut but not so it cuts into the bottom of
the L-fence. That’s been done in the
here.
The last step is to adjust the fence so the outside face
of the blade is about 1/32” back of the edge of the L-fence as shown
below. This keeps the saw blade from
cutting a notch in the straight reference piece. The piece can now be cut using the straight
edge that’s attached to the walnut as a guide against the L-fence.
After making the cut this is the result, a nice smooth
straight edge. In the bottom photo you
can just see where the walnut is sticking out in front of the oak straight
edge. That’s due to the 1/32”
offset. This way I get to keep the uncut straight edge piece to use again.
Last is straight line pattern cutting. Process here is to make a master pattern then
double face tape it to a blank. This
assembly is then used to set clearance under the adjustable part of the L-fence
and last move the table saw’s rip fence so the outside face is flush with the
L-fence. This is the same setup as used to rip a straight edge except for the 1/32” offset. Here there is no offset and that’s so when
the cut is made it’s perfectly flush with the pattern making an exact
duplicate. The photo below shows a
sample plywood pattern set on a solid piece of cherry. In use the L-fence rides along the pattern
edge while the table saw blade cuts a perfect match to the master pattern. In this case since the base of the pattern is
set flush with the bottom of the blank three cuts are needed to make a matching
piece.
No comments:
Post a Comment