If you're using a die, just be sure to chamfer the end and get a straight start, otherwise fuhgetaboutit. A thick cutting oil like Heavy Duty Tap Magic, or Castrol Molydee work great for high temp materials. Try not to back off too often, because this is when the cutting edges of the die will chip, and once they chip, you might as well throw them away. As long as the chips are falling out and not loading up, you should be able to just run the die down in the forward progression til you get to depth. It will really help alot too if the pipe is actually round, and not too big for the die. When it comes to cutting threads, especially with taps and dies, a few .001" can make a HUGE difference in the quality of the thread and the life of the tool.

Jason

The trick (IMO) to machining titanium is to use the proper feeds and speeds. Here in our shop we machine titanium everyday, castings and solid stock. We have experimented with many different tools and oils etc. For drilling, I have found that cobalt drills work better than solid carbide, because they don't chip, unless you go to an inserted indexable drill, preferably with thru spindle coolant. For milling, carbide is definitely the way to go. I run cobalt drills at 40 surface feet at .001-.002 feed per revolution, and carbide endmills at 125 SF at about .001-.002 feed per tooth. I have found that at these surface speeds, you can run all day long with minimal problems, once you try bumping up the speeds even a little, you will most likely spend all day changing out tooling. As for threading, single point threading is the ideal way for cutting threads, but tapping and dies are going to be challenging and a pain pretty much regardless of what you use. A good quality tap (IE, Emuge taps) work real wel, but are priceyl, and Greenfield dies are good quality too.

Jason