Yesterday I sanded the 7 rings flat and glued them into stacks, and last night I rolled the tone ring parts and the tension hoop. The ring roller is new to me last fall, prior to that I bent tension hoops by hand. It’s fun to use, as it takes a job that required a lot of effort and was inexact and makes it effortless and precise. I buy brass in 7 foot lengths, and each length will do two 11 or 12 inch banjos without too much waste. The ring roller does the whole bend in one pass, so it is quite fast. I have a plan to make it so that I know exactly where to set the roller for each type of product, but I haven’t gotten it done yet so for now I eyeball it. The scalloped truss is made from 3/16×5/8″ brass.
The top hoop is 1/4″ round brass.
There are little spots in the rollers for the round brass to ride in.
The tension hoop is 1/8×1/2″ brass, and here they all are together
I used the bandsaw to cut the unbent end off each piece and then used my handy list of measurements to find the correct length. I have a piece of 1/4″ aluminum plate that I use for gluing and soldering and other odd jobs. The brass turns red when it’s just about ready for the solder.
Today I used a sewing tape on the inside of the scalloped truss to mark the high points, and then used a plastic lid to draw a nice arc between them.
Then I used the bandsaw to roughly cut the scallops. I wear a welding glove on my left hand since that side can get a little warm as each cut comes off the blade. That hand is behind the blade so it is relatively less unsafe to wear a glove on that hand. I am not suggesting that anyone try this at home, as they say.
Then I used the spindle sander first with coarse and then with fine grits to clean up the bandsaw cuts, and used the fine drum on the inside and outside of the ring.
Then I put the rim blank on the aluminum faceplate and turned it, and fitted the tone ring to the rim.
Then I mounted the inner rim on an old particle board faceplate and turned the face and the inside only. I use the ruler to see when the inside of the rim is straight and parallel with the tubes of the Shopsmith bed. I have to move my head to see both parts of the yardstick, so the camera can only see part of the job at a time.
My last step for now was to mark the outer rim at the point where the centerline of the neck and the tailpiece will be, and install blocks in those places. I used the sander to match the outside of the blocks to the rim and to put a shallow angle on the inside of the blocks. The reason for will become clear tomorrow when the inner rim goes in.