Drilling output shaft

a_kelley

a_kelley

mechanical fixer
Joined
Jan 26, 2010
Location
Rutherfordton
Anyone got experience/tips on drilling an output shaft with intents of tapping the resulting hole? (think hack & tap) I've not tried to drill it yet, but I believe it's case hardened. Would I be time and effort ahead to get some high quality masonry bits (tungsten carbide tipped) sharpened to a drill point to do it, or will Cobalt bits do the trick? Or should I heat the shaft hole and let it cool gradually, drill & tap, and restore temper by heating and quenching?

Thanks!
 
a_kelley said:
Anyone got experience/tips on drilling an output shaft with intents of tapping the resulting hole? (think hack & tap) I've not tried to drill it yet, but I believe it's case hardened. Would I be time and effort ahead to get some high quality masonry bits (tungsten carbide tipped) sharpened to a drill point to do it, or will Cobalt bits do the trick? Or should I heat the shaft hole and let it cool gradually, drill & tap, and restore temper by heating and quenching?

Thanks!
Click to expand...
A decent quality tool steel should do it, but if you're worried, just order a proper carbide drill.
A good 3/8" bit is like $50-60, or a cheap one from MSC is less than $30:
https://www.mscdirect.com/product/details/71210249
 
If it's case hardened, the hardened surface is usually fairly low depth.

Be careful about what you're using to drill it with, as high hardness drill bits are rather fragile and generally intolerant of sideloading or bending at all. Don't chuck it up in a Dewalt, basically.
 
I used to have a few $$$ Cobalt bits, but they were borrowed by other people and ended up being junk. And yeah, they were 30-60 bucks each. Guess this is a good excuse to get some more.
 
Second good bit. Don't try heating or treating. Bad news all around on that approach. Good speed, steady firm feed and make chips. I drilled some lower grade tool steel on a mill tonight with carbide.....following a run of the mill center drill that wouldn't even scratch the surface. Both MSC sourced products.
 
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