Get a bit of hollow cast bronze and make the "C" shapes, looks like you may get two from one piece and the third from a smaller dia. Then Silver solder on the other bits.

Following on from Jasons suggestion, I happened to be on the Metals4U site and I had a look, they do 660 tube in a range of sizes up to 4 inch O/D with various wall thickness and PB1 up to 6 inch. I thought they had a minimum of 50mm cut length but it looks as if with the larger bronze tube they will cut even shorter.

This might be daft, if so someone will let me know, but can you machine them from wax, then send the wax bits to a lost wax casting man? Or even from polystyrene (they might be a bit small for that, but it works for full size loco cylinders) see **LINK**

Hi Duncan

This gas turbine inner section NGV machined as a tryout
from prototyping wax could be used for casting purposes
if tided up a lot ,as with all castings the pattern is the part that
takes up most time,the second photo is some model engine
parts from the early 90's ,the exhaust stub the semi-circular
part with the slot through the centre required the complicated
mould seen here top left .

John

I know you said you have changes the drawing now but if optimising material usage saves money the layout you show could be much improved (as long as its being cut with steerable blade like a fretsaw, but much more manly.

If these forks sit in grooves of gears that are close fitting on the shafts/splines then would just say 120 degrees of the circumferencial engagement rather than 180 be OK, would save even more material.

Ian P

What's the gearbox for? How much load? What speeds?

Plenty of motorcycle gearboxes use steel selector forks. Usually hardened but presumeably to a lesser degree than the hardened gears they engage with. The selector forks are only under load when shifting gear. Otherwise they are merely a placeholder and under very light load.

So you could get some 10mm thick steel gauge plate and cut the parts out and machine them then harden and temper them.

Or go to a motorcycle wreckers yard and get some ready-made selector forks out of a trashed gearbox.

M-machine can also supply 3/8" and 1/2" thick Phosphor Bronze PB 102 sheet so you could probably have a piece cut to the size that suits you if required/preferred.  And, referring back to your original post M-machine can also supply brass flats 1/2" thick up to 6" width cut to length required.

Regards,

Phil

Edited By Weary on 19/09/2019 09:02:44