Drilling CL 72 crank for a stater clutch

[Kthomas55]

Latest
It is for a CB77
I went through a pack of diamond burr bits . There were four that I could use. I’m down 2-3 mm and I thought once I got past the surface hardness a drill could start to mak a dent. These cranks are hard as hell. I think I will probably need to go another 4 mm or so to reach the cavity but ?
I may buy one more burr set 9.00 dollars.
I’m about ready to call it quits until I find another crank .
If anyone is thinking of doing this heed my warning. Don’t do it.

[Kthomas55]

Update:
I decided to try some 1/16 inch drills I had for drilling safety wire holes. They work. Cheap drills from Lowes going relatively slow work. (This is after getting down 2mm with burrs ) Then I enlarge with the 2mm ones I have that won’t cut anything. I’m down 6.5mm and need new drills. I hope there is a hole in there otherwise I’ve waisted a lot of time,energy,and money.

[Kthomas55]

Success !
I finally reached the cavity at about 7mm or so. It was weird because once I got through the exterior hard part with a burr bit the drilling went easy once I had the right bit. Then it stopped and none of the bits I had would go any further between 6.15 and the cavity. I borrowed several machinist bits of various configuration the go the rest of the way. It was almost like a tiny piece of bit broke off and wouldn’t let me the rest of the way in but I didn’t remember breaking one off. Also, I couldn’t see anything in the hole.
I ended up using probably 50 dollars worth of bits to make a 2mm hole 7mm deep. It was a Pain. I’m sure someone could have done it with a lot less irritation, time and money. Oh the Joys of Learning things the hard way .

[G-Man]

Well done for persevering.

G