Dear Iris, A high speed steel drill should do the job OK. Use a
slow speed when you’re drilling - you’ll find that the Ti doesn’t
"grab" as much. The drill might be burning because it’s running
at too high a speed. You shouldn’t have to be “drilling under
water”. That’s a bit startling. I am trying to imagine how you
might do that. It doesn’t sound very safe.
When I’m drilling Ti, I tend to “free” the drill regularly by
pulling it out of the hole so the swarf is regularly cleared from
the cutting edges and spiral. Neither do I apply too much
downwards pressure while I’m drilling.
Are you drilling through the diameter of the 4mm round wire, or
down through its length to make a chenier or tube? I do both and
find it best to use my motor-in-the-handpiece unit (Volvere type)
rather than my flexible shaft or drill stand. The motorised
handpiece seems to give me more control and sensitivity to the
"grabbiness" of the Ti.
Please let me know if the above helps. If you are anywhere near
Sydney, give me a ring on 02 9580 2808. I’d be only too pleased
to advise further or help.