Guys, it's been about 3 years since my last attempt at making a liner lock. I was drilling the pivot hole in the titanium and it work hardened on me and won't drill anymore. I was using plenty of cutting fluid and a slow speed.

I've had this happen before and I can't remember...is it slow speeds or faster for ti?

Thanks!

Cobalt HSS drill bits with the "aircraft web" routinely do an acceptable job drilling through titanium. Slow speed and fairly high feed pressure is the ticket. Tap-Magic is what we used to assist in removing the heat from the tool contact area. Small cans with a squirt tip works well but no need to flood the area.

Once the surface gets work-hardened it is essential to get through it before restarting the "drilling" operation. I think you could go with a carbide burr (much less expensive than a solid carbide drill bit- especially if the burr is soldered to a steel stem). What size is the hole you are drilling? I may have some bits or burrs (left over from my days doing machinist stuff). PM me if I can help.) Reaming to finish the hole size after drilling assures ending up with the exact size you want.

Hey Old Gar, thanks for the quick reply. Yeah, I was thinking slower speeds. I just got carried away and didn't back out of the hole enough to keep it from getting too hot. I remember now when I worked with it before I drill,back out, drill,back out, etc. It used to take a good several minutes for me to drill an 11/64 hole in .063 ti. But, I didn't have the problem I now have

Oh well, I'll just cut another piece and start over. Course I may try and use a burr and salvage the piece too......

Anyway, thanks for the quick reply and to remind me that I was doing it almost right.

Oh, I ream after the 11/64 to 3/16. May not be right according to the charts but I don't have a chart for the proper size and it works well for me.

Ti sucks to work with. even with thin stock (.050 in my case) it's a pain. Cobalt bits or tipped bits are the way to go. I found that out the hard way

Adam, yeah I use cobalt on all knife materials. Except for the solid carbide I use to set the detent hole in the hardened blade.

DARK - - Here is a different perspective. And I agree with most of what this fellow posted. Usually there are no surprises working with highly controlled metal alloys. Some of the chinese crs might show up with unmelted ball bearings in the roll!

This is from a web site for Machinists---------

""Subject: Machining titanium
I love machining titanium and other super alloys.I,m a technical support engineer for Seco Tools in Holland.When working with this material its always a challenge to get the best out of your cutting tools.Check out http://www.secotools.com.I have read some interresting replies,if I can give you a tip,use PVD coated micro grains with sharp geometries,change the cutting edges on time,dont think I can just manage one more pass if I,m lucky.Thats the Murphy Law,its beter to change a cutting edge of 1 dollar instead of a part that costs 100 dollar.""