I have cut Ti every day at work for the last 25 years. We use only carbide tooling because HS doesn't hold up long. In the long run you will spend less on tooling with carbide. If you cut a lot of Ti, stay with carbide tools. HS drills work fine with it. Most of the time I like to grind drills so the point isn't perfectly centered so the drill cuts oversize a little. This goes a long way in making your drills last longer. Sometimes a standard drill will get dull and you will swear it got squeezed down as it gets melted down in diameter. Hand grinding a new drill will give it just enough run out to cut down on this problem.  Tapping Ti is best done with special taps made for it. Standard HS taps don't tap it worth a darn. I wouldn't plan on reaming it unless you use carbide reamers.

As far as catching on fire goes. Thick chips around .002 thousandths thick or better are really hard to catch on fire unless your cutter is really dull. Really thin chips that are like steel wool burn white hot and are easy to catch fire. Same goes for saw dust from cutting it on a band saw. One time we had someone welding overhead on a crane and some sparks got in a chip barrel full of Ti and aluminum dust from the band saws. It burned and smoked up the whole building so we got the day off due to the smoke. Lucky there isn't much to burn in our machine shop. Big parts will not burn. If you ever get a thick block of Ti to catch on fire you have bigger problems than that block burning. That will take a lot more heat than you will make just cutting it. Even getting thick parts say 1" in dia. red hot to braze it won't set it on fire.

Not sure how 303 Stainless Steel would hold up to whatever you would like to make. 303 cuts nice and is much easier to work with.

I'm finishing up on my latest spray etching tank http://www.prototrains.com/etch3/etch3.html where I have a titanium heater and titanium "spider" for holding the workpiece.

Cool project . .  and kudos for the fine craftsmanship. After pondering the potential hazards of messing with strong acids, and condidering the unsophisticated projects that my limited electronics knowledge would allow, I opted to go with routing PC boards. Very simplistic compared to your rig, but it's fun for me.

Here is my old mill cutting a PCB using my die grinder for a spindle; http://www.youtube.com/watch?v=r9Zf_5yHB1I

Steve, how did the toilet seat hinge end up ? I'm kinda working on a similar hinge project with titanium (but not a toilet seat  ). Ive used the main online ecom companies before and also got small titanium pieces, bars, tubes etc from a chinese company www.norstl.com who are pretty helpful and have done some machining for me in the past too. They've done some machining in quite a few different grades which is nice. Bits for bikes, exhausts etc

I think from what you have said given the application anything more than grade 2 would be overkill. The differences in the alloys really only become noticeable in extreme conditions..

Would be good to know if your seat is still going strong !

Hi

Never got round to it as I couldn't find an easy source of Ti, been through another 2 sets of hinges though 

Steve