So its been a bit of break over Christmas and New Year, but I’ve still been getting some progress with the tuners. Just before Christmas I went to my friend Dave Mattey’s to try some Sand Casting. Dave casts the most beautiful mandolin tailpieces in Bronze and we had a go at the tuners
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What fun! Another skill I’d love to learn….
I would describe the result as not bad - we struggled to get an exact split in the middle and some sand stuck in the ring, leaving a little bronze to cut and file away.
I then spent two days making post/pinion gears. This is a slow process with each pinion requiring 8 teeth to be individually cut. Its a zen-like process where I really had to maintain focus to ensure I turned the dividing head the exact number of turns and the same with the drop cut into the metal. Cutting the gear teeth is just one step as the ends need drilling out and a collar cut on the other end.
Here are the brass rods just before cutting the teeth:
Just after Christmas I visited Andrew Braund to try some investment casting.
We decided to add Silicon to the brass to add strength. Silicon wont melt at any normal temperature, but it turns out you can dissolve it in molten brass! With some crazy flames…….
The results are impressive:
The heads are really clean and the heads and worms need minimal cleanup. The only minor issue is that the resulting casts are a little smaller than my original design, despite scaling up the pattern by 4% when I printed it. Luckily they still fit into the frame.
As a result I rebuilt my test jig with one of the new heads:
I’ve tested this up to about 12kg of tension (118N), and it works great. No slipping and easy to tune certainly in the 8-10kg tension range.
That has encouraged me to make my first “five-on-a-side” tuner:
It still needs clean up and some endcaps but it feels like a real step forward!