Drilling SS need tips please

Need tips on drilling holes in stainless steel saw blade for my rear tine tiller converted to wire trencher.
Basically I have a 14" fire and rescue blade that needs 4, 3/8" holes for the hub/collar to mount up (I'll get pics up later).
Anyway I'd tried this years ago with regular drill bits and it was a joke.
I know I need low rpms and some oil. What I don't know is exactly what kind of bit is best????titanium, carbide etc.
Please help any recommendations appreciated.

 

Hey,

135 Deg Split Tip Cobalt bits work well with lube the coatings that come on them are fine for extending the life of the bit but thats all they really do. For stepping to a 3/8ths hole I would go 1/8, 5/32, 3/16, 1/4, 5/16, 3/8 here is a link to a speed and feed calc for you. http://www.ttp-hard-drills.com/drilling-speed.html This is all with out knowing exactly what that blade is made of I looked there are several dozen variations lol. I have used the above method drilling may types and grades of stainless but every alloy is DIFFERENT. 98tacoma is very correct it takes a millisecond to work harden Stainless and then your done unless you happen to have some really expensive industrial diamond bits one of which might run you 60 bucks plus. You want to use a cutting oil not just regular motor oil btw.

Cypher

 

Sweet guys thanks for the tips!

 

Dont use carbide unless everytihg is really stable. Cobalt should be fine, like others said, do it in steps. Only concern is that it may be a treated stainless since its a type of blade. Common 300 series stainless should be ok but if its a form of precipitation hardened stainless it could get pretty tough.

 

Slowly but surely (hopefully).

 

OMFG.... you didn't say you were doing it with a hand drill! I assumed you were using a press.

Wow... That's going to take some time and a LOT of oil... I have a hard time getting enough pressure on a hand drill to go through SS.

 

Oh yeah I know better, but my drill press and two others locally are all too small a radius for a 14" blade to set on so I figured F it, I'll just go slow and use an ass load of oil and see what happens. I've actually made good progress . I'm probably 10-20% along after 45 min of work LMFAO. Definitely sacrificing several bits to appease the gods of cutting mayhem.

 

How did you make out?

 

Just getting ready to hit it again in a couple hours.

 

Got a set of cobalt bits and finished up. Went surprisingly well. Probably another 45 minutes of work.
Thanks again guys