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| Airbrush Setup |
To give the client a good feel as to what the Leopardwood
would look like finished I cut a small piece off one of the turning blanks. Using an airbrush I gave it
three coats of gloss instrument lacquer that was left over from an electric guitar I had
made. This shot is with three coats lacquer
applied but not yet buffed out. I want
the lacquer to cure for a few days before buffing.
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| Leopardwood with Lacquer Finish |
While the test finish was curing I decided to make a
prototype of the bearing edge we had come up with. The first one made to our preliminary plan
had some problems – the bump on the top is only 1/32 of an inch tall and in
real life was so small that I was concerned it would not give us the desired
clearance between the bump and the outside arc.
For reference the inside of the drum is to the right of the sample. A second sample, increasing the bump size to 1/16” gave a
better result. Well, at least from my
understanding of the design intent it looked like a better result. I sent both of these photos off to the
client who is the acoustical expert for his comments and thoughts. I should add that the area to the right of
the pencil line would be removed in the actual piece.
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| Bearing Edge Options |
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| 3rd Bearing Edge Option |
His response was to suggest taking a look at an offset
double 45 degree bearing edge. Based on
his description I milled another sample and sent the photo off to him. We don’t need to make a decision yet as the
edge design won’t have a bearing (no pun intended) on how I build the shell
until the very end.
For the shell itself my initial thought was to make each layer out
of 12 individual segments. I have done several
segmented pieces and the 12 pieces per layer seems to work out pretty
well. However, they are all smaller
diameter than the drum and I got to thinking that the larger diameter might not
look right with 12 pieces. A drawing
using an 18 piece ring looked better so I built a mock-up of each to
check. Seeing both samples side by side
confirmed the 18 piece looked better. I
sent the photo of both pieces to the client and he agreed that the 18 piece
ring would look better so that's the way I will proceed.
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| 12 and 18 Segmented Rings |
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| Buffing out Leopardwood Sample |
By now the lacquer on the Leopardwood had cured enough that
I could finish the finish. In practice I
will wait longer but as a sample it was OK.
The process starts with a wet sanding with 12,000 grit to remove dust
nibs and the like. This is followed by
buffing which consists of mounting a cloth wheel on the lathe, charging it with
a very fine polish then buffing out any irregularities. That is followed
with a different wheel and
carnauba wax. Unfortunately the photo of
the finished piece looks just like it did when I started. What the photo does not convey is just how
smooth the process makes the finish.
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| Buffed Leopardwood Sample Finish |
Because of the 14” diameter of the drum shell I felt that my
existing 3” diameter face plate would not be adequate to securely hold the
segmented blank in place without excessive flex and vibration. This gave me a good reason (excuse) to get a
nice Oneway 8” diameter cast iron faceplate.
When the faceplate arrived I could start building the mounting fixture. It consists of a couple layers of ¾” MDF and
a sacrificial segmented ring. The MDF
layers were cut out on a bandsaw then screwed to the new faceplate. Once mounted I turned the edges true and
smooth to help balance things out.
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| Mounting Fixture in Progress |
I wanted a segmented mounting ring that would hold the
actual drum shell out away from the MDF so I had some room for turning. The ring needed to be stable but I did not
want to use any of my good hardwood for it.
The solution was to use a piece of 2x6 I left over from the test Maloof
chair. It has been sitting in the shop
for a good 10 months so it’s dry and should have stopped moving. Unfortunately, in that time it cupped,
twisted and warped. In other words, no
resemblance to flat and square. That’s
not a huge problem it just took a little work with the bandsaw, hand plane,
thickness sander and tablesaw to get the flat and square blanks I needed. Before cutting the segments I let the blanks
sit for a couple of days to make sure they were done moving.
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| Blanks for Sacrificial Segmented Ring Layer |
It was a good thing that I let the blanks sit as one of them
developed a bit of a twist sitting. That
was OK since I had made a couple of extra blanks in case something like this
happened or if I had a problem cutting the segments. With the blanks ready to go I set the jig up
to the required size and cut 18 segments.
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| Setup for Mounting Fixture Ring Layer |
With the pieces cut it was time to glue up the ring, here is
the setup. Glue plus the pieces which
are clamped together in two groups to make applying glue easy. I have two sets of hose clamps to pull all
the joints tight, a drill and a hand nut driver to tighten the hose
clamps. A hammer to “adjust” the pieces
so they are in alignment once the clamps are snugged down. Lastly several pieces of an old shirt in
water to clean up the inevitable mess.
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| Ready to Glue Ring Together |
No photos of the assembly as it’s controlled chaos to get
everything done within the glue’s working time.
Seven minutes after applying the glue all the pieces are in place and
the clamps are tightened. Three minutes
later the glue is cleaned up and the ring is set aside to cure.
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| Sacrificial Ring Glued up |
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| Flattening Ring with Thickness Sander |
After letting the glue cure overnight I took the hose clamps
off and ran the ring through the thickness sander. No matter how careful one is those 18 joints
will not line up perfectly nor will the opposite faces be exactly parallel. A few passes through the sander takes care of
both problems. In the end I probably
only removed only about 1/32”.
With the mounting ring flattened I centered it on the MDF
base and installed 19 screws to hold it in place. Out of curiosity I put completed fixture on
the scales and found it weighed 17 pounds.
Last was to put it on the lathe and true up the outer edge.
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| Mounting Fixture Ready to go |
Next Up – Cutting Segments, Glue-up & Turning
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