While I had cleaned up the parted edge it was not really
finished. I needed to get a flat square
surface before I started on the bearing edge detail. To get that I started by clamping a couple of
sheets of 120 grit sandpaper to the extension on my table saw and chalked up
the parted edge.
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| Chalked Edge - Ready to Flatten |
Flipping the chalked the edge over I carefully sanded that
surface checking frequently to see when all the chalk had been removed. When it was gone I knew I had a flat and
square surface.
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| Flattened Edge |
To get the double 45 degree bearing edge we had decided on I
used a 45 degree carbide chamfer bit in the router table. From my experience turning the shell I knew
that Leopardwood is very hard. What I
did not know was how brittle the wood was and how susceptible to chipping it could
be while being routed. With that in
mind I decided to error on the side of caution using climb cutting and taking many passes on the
router table to cut the bevel.
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| Bearing Edge Detail and Router Setup |
The router in my table is a 3½ horsepower model and to get a
feel for how the leopardwood would route I started with a cut just over 1/16”
deep. Surprisingly, even with that small
a cut I could hear the load it put on the router. As the depth of the bevel increased the size
and amount being cut increased I gradually reduced the cut depth to keep from
loading the router too much. The last cut was just over 1/64”. Here the top and bottom inside bevel has been
cut. I will wait until after I get the
holes for the lugs measured and drilled before I cut the outside bevel for a couple
of reasons. First, I wanted a flat
surface for reference when I layout the lug holes. Second, where the two cuts meet there will be
a fairly sharp edge that I do not want to dent or otherwise damage so the later
it’s cut the better. I will probably
make that cut the next to last operation.
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| Inside Finished Bearing Edge & Close-up |
Next I needed to build a jig to hold the drum in the drill
press so the mounting holes would be on axis to the drum center. I also wanted a softer surface against the
drum so as not to scratch the finish sanding job. To that end I beveled a couple pieces of
extruded Styrofoam to closely match the curve of the drum, mounted them to a
piece of MDF and clamped it all to the drill press table.
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| Jig for Drilling Lug Holes |
Once I got the new lugs I could measure for the hole size
and layout where they will go. With that
done I set the shell in the jig, used a square to align it so the drill hit my
mark and is lined up with the shells center line. Now with everything braced in place and
square I clamped a piece of 4” PVC pipe in place. This will act as a backup so when drilling
the holes the drill would not blow out the backside of the shell when it cut
through. If you look at the right image
you can see the white of the PVC at the bottom of the hole.
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| Jig and Close-up of Hole |
After getting everything set for the first hole it’s a
simple matter of loosening the band clamp, rotating the shell 36 degrees,
aligning everything then drilling the hole.
The setup takes way longer than the actual drilling. Repeat the process 9 more times and Ta-Da
it’s done, ready for the lugs to be attached.
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| Shell with Lug Holes Drilled |
At this point I did a test fit with all the lugs, tension
rods, heads and hoops installed.
Everything aligned, was plumb, square and fit just perfect.
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| Test Fit |
With that done it’s on to adding the last two pieces of
hardware. The throwout which controls
the snare on the bottom head and it’s anchor on the opposite side of the
drum. Since we had not decided their
location as to how far up they went on the side of the drum a brief discussion with
the client answered the question, 2” from the bottom. More measuring and 4 holes later they were
mounted.
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| Throwout and Anchor Installed |
The next step was to cut the outside part of the double 45
bearing edge. It is cut the same way as
the inside, using the router with a 45 degree bit. After a couple of passes I marked the flat
area on the edge with a red marker shown on the left photo. With that as a guide I raised the router bit
a little at a time until only a trace of the line remained, right photo. Lastly, a light sanding rounded and blended that flat
surface into the two 45 degree angled cuts giving the bearing edge we wanted.
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| Cutting Outside of Bearing Edge (L) in Progress, (R) Ready to Blend |
Only one bit of woodworking remained and that was the arc
for the snare cords. To make this last
jig I took a full size print-out of it, laminated that to a piece of cardboard
and cut it to shape. We had initially
set the cut depth at 3/16” as shown here but in a later discussion the client
wanted to decrease the depth of the cut from 3/16” to 1/8”. That was no problem I just adjusted the
template I had made down by 1/16” and clamped it in place.
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| Snare Cut Template |
Using a small drum sander in the Dremel tool I cut the rim
to size then did the same on the opposite side.
Some hand sanding to clean up the surface, ease the edges and I was
done.
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| Finished Snare Cut |
That only left some final hand sanding and I was ready to
apply the finish.
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| Sanded Shell Ready for Finish |
Next Up – Finishing & Another Problem
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