Drilling and tapping hardened steel

[Naiveambition]

Thanks fellows for all the tips and tricks. I located two straight flute carbide drills that supposedly drill thru files. So this is the next step. If I can't make it thru with these I will probably try the masonry bit to make a plug. The threading is still iffy at this size , so not sure what will happen. If I can locally anneal then problem solved. I liked the idea of using a rod in drill press to anneal, as I can't anneal the whole part then reharden,temper etc...

As for hardness no clues but, a file will not scratch it so I'm guessing around the hardness of a file. I'll update sometime this week and let u all know what happened, and if I need a next step

 

[Nick Hulme]

And the 10,000 RPM lathe spindle to do it. In that magic drawer.

A fast Lathe Spindle? that would be no good for thread milling, just really fast conventional threading, try that to a shoulder!
For thread milling, and other things, I have a Tool Post Spindle and pfft to your 10000rpm, it does 15000rpm to 30000rpm with tools up to 6mm shank ;-)

 

[Naiveambition]

Thought I should offer some closure for anyone interested in this thread. Was finally able to summon enough courage to go for it. Lol.

I had bought a special set of straight flut carbide drills ( forget their name but can be found using google search for file drilling) They performed better than I anticipated. Drilled without annealing and no oil at 2000 rpm. Went thru like I was drilling aluminum. Well the drilling went fine but not the tapping. Broke off 6/32 tap. Maybe I could of waited on a two flute tap and finished, but I got antsy and redrilled another hole next to it , then enlarged with a masonry bit to fit a plug. This had the added benefit of also removing the broken tap. Was tapped for 10/32 and will spot weld into place. File flush and were in business.

I may try drilling thru a file just for the heck of it so I can test what these drill bits are capable of. But on same note I don't want to bust a 15$ bit on testing if it goes bad. Maybe in a couple weeks I can summon the courage again lol