My father bought a well used potato elevator for 30€. Elevator chain wheels were worn out pretty badly and he decided to fix then by welding some more material. Then chucked them to me "You have a milling machine, mill some teeths". Also gave some measurement that looked reasonable and I manged to mill the teeths that more or less followed the welded contour. All's well?
Suspicious as I am, I asked more measurements on the chain itself - something did not add up. PCD was about 27 mm too big. I should be 150 mm. I called back and asked how much did he weld to make up the worn part? Two full packages of welding rods!
I tried to plunge slot drill into them....Broke two slot drills with rotab. Then bolted the sprocket wheel onto mill table, only with a spacer and next slot drill broke when went into weld about 0,5 mm. Good only knows how many times that poor wheel was welded before and with what. Part of the weld is like chewing gum and part is pretty hard and work hardening.
I'm asking a local water/laser cutting company how much it would cost to cut them from 16 mm steel plate. I can't afford using slot drills at this rate. And spend allready three days of my making a fixtures/arbors and reducing it's heft by turning it smaller.
Alternative plan is to drill bottom of the teeth with hsco drill and offer an angle grinder to that bugger.
And I don't have very good idea of the actual tooth form, because it's not a classical chain wheel but a very agricultural view of it.
This is going to a character building experience.