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Banjolele rim #1 - the first segment layer

After a few practice attempts (aka false starts) at making rim segments last year, this weekend I had my first proper crack at it. The problems I'd run into previously were mainly due to starting off with non-squared stock material. This time I picked a ropey log from the pile of pallet wood I have (allegedly Mango, but could be anything) and squared it up. This particular piece was not the best, mainly consisting of knots, nail holes and worm holes and a little bit of wood holding everything together. I don't want to screw up on something that was too nice, but what started off as a fairly substantial piece only yielded enough wood to make one 12-segment layer for the banjolele.

Anyway, once I'd squared up the stock, I needed to cut the segments at 15 degrees on the mitre saw. The calculation to get the correct angle to set the mitre saw for segmented is

(360 / #segments) / 2

which is where the 15 degrees comes from in this case.

First problem! My mitre saw had fixed positions for common angles, 15 degrees included, but when I checked the angle it was 14.3 degrees. That's simply too far out when making 24 cuts, so I had to set the saw manually using an angle gauge.

 edit: I've since found that it is possible to true-up the preset angles on the mitre saw although I've not been entirely successful so far.

Once I had the saw set up correctly, I cut the segments, flipping them over as I went along. I marked alternate segments A and B, so that I'd end up with six of each which would be alternate, and every other one flipped over when making the dodecagon. Doing this compensates for the saw blade being not exactly vertical (this only works for an even number of sections)

I found a great series on block rim building on youtube by Richard Brown and used a few of his tips to do the glue-up. Here are the 12 rim segments laid out on a stretch of masking tape against a straight edge to help in keeping it all level.

segments stuck to masking tape
Here is a close-up, where you can see a couple of the segments marked 'B'. The  'A' segments are marked on the opposite side.

close-up of segments
Next I rolled up the tape with the segments on to see how it looked. It was pretty good, and I reckoned once clamped everything would pull together quite nicely.

trial fitting
To clamp everything, I used a large hose clamp. I first tightened the clamp partly, then sandwiched the whole assembly between two pieces of MDF which I clamped together. Then I tightened the hose clamp, removed the dodecagon from the sandwich, and removed some of the glue squeeze-out. The joints looked as good as I could hope for, so fingers-crossed this will turn out OK. There are some pencil lines on the segments which from distance look like bad joints, bit the joints really do look pretty good.

glued and clamped

Another 24 hours to wait now.


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