Drilling titanium?

[JerryCPP(WA)]

I need to cross drill or mill a 1/4 inch hole in 1 1/8 inch grade 5 titanium. I need clean hole with a very tight fit for the bolt that will go through it. I don't know whether to use HSS, cobalt, or carbide. I've read "Slow with lots of pressure and cutting oil," but no real answer as to what material will work best for the end mill or drill bit. Titanium is very pricey, so I don't want to mess it up. Has anyone here actually done this? If so, what did you use?

 

[Janicholson]

Down this list is the practices I use most. Success depends on carefully monitoring the rate of change in the depth of the cut assuming uniform feed pressure. Tap Magic Brand cutting fluid is a blessing as it finds its way onto the edges. As soon as the cutting rate slows, it is mandatory to sharpen the drill. Heat and work hardening are radical issues. Jim
Info

 

[JD Seller]

DO NOT let the bit get dull. Even the least little bit of the drill turning and not cutting will work harder the titanium to where you can cut it even with carbide cutters. I have used a carbide end mill with coolant to mill titanium. I do not know if it would work at the depth your needing.

 

[jeffcat]

Going back to when they were building the SR-71 black birds. They had to develop all kinds of special tools and procedures to work with that stuff.

 

[rlp in Co.]

Use cobalt bits and as others have said, heavy pressure and slow speed and keep the bit sharp. Do you have a scrap piece to practice on?