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Ok, here's a question for the nerdiest of the nerds;

What kind of rod do you use to make rotary valve control arms? I've been using 625 German silver, but I'm wondering if there's an alloy that is more rigid. For example, I've been researching an alloy called Invar 36, that has steel in it.

I will be using Dubro 4-40 ball sockets, so it will need to be threaded easily.

Of course, why didn't I think of that

Actually, I experimented with threading the rod to 6-32, and tapping the ball link to match, and that gives the rod a little more strength, especially considering that the threaded part of the rod where it enters the ball link receives a large amount of the torque.

I have a box of stuff salvaged from saxophones I've parted out. I don't know what those long sax keys are made of but they are some tough stuff and lend themselves well to brazing. The hollow ones are great for fabricating tube and rod hinges.

Is it common to use drilled rod for this application? All the ones I've made use solid rod. 1/8" seems to be the right diameter, though.

For the lever parts, I like to use 7/32" (5.5 mm) or 1/4" German silver rod stock.

https://imgur.com/gallery/vKHldam" target="_blank

Great - good to know!