Cobalt and Carbide drill bit speed

[BUDSVTX]

I have to drill a 1/8" hole in the keeper end of an exhaust valve for a 1924 Fairbanks Morse engine. The new valve I am using is very hard, what speed should I use for a Cobalt and Carbide drill bits. I will drill a 1/8" hole in the end of the valve so that I can install a keeper and cotter pin. Doing this will make it closer to original than a regular valve spring keeper.

Thanks
BUD

 

[rlitman]

What is the new valve made from?

 

[BUDSVTX]

Unknown, it is hard, is non-magnetic. I don't even know what car it came from. The engine was given to me and the head was rebuilt at a shop somewhere, the valves came with the head, but it was never finished.

BUD

 

[Astro_Pneumatic_Tools]

Start with 1,500 RPM on a 1/8" drill bit then look for chip color and shape. If the chips remain grey/shiny and come out like cury ques then you're okay. If you get chatter, grinding sounds, or the chips start looking blued less pressure and less rpm.

 

[rlitman]

Unknown, it is hard, is non-magnetic. I don't even know what car it came from. The engine was given to me and the head was rebuilt at a shop somewhere, the valves came with the head, but it was never finished.

BUD

Non-magnetic is not a good sign. Could it be stellite?
Know anybody who does EDM drilling?

 

[BUDSVTX]

It may be stellite. They may have sold him a stellite because it is an exhaust valve. It is hit & miss engine, running at no load, so when the governor is locked for speed, the valve is held open and does not get hot.

BUD

 

[rlitman]

Yeah, that's how hit/miss works. Neat concept.
Well, anyway, best bet is to follow Astro's advice and see what the chips look like and how it sounds. On almost anything other than a valve, I'd consider taking it to the grinder for a spark test, but you probably can't afford to have grind marks on it anywhere...

Good luck.

 

[leg17]

Won't drill Stellite with HSS.
You might be better with EDM.

Not sure if Stellite will even withstand the forces of the keeper system using the thru hole.

Anyway, Good Luck
Keep us posted.