So in building a turbo adapter plate i have run into an issue. The holes in the cast are 8mm i need them bored out to 3/8in or around 11mm. The cast iron is 1/2in thick as well. I was using a hand drill with a titanium bit attached and made it about 2 or 3 mm deep before i realized it was useless. So the questions come up
Does a drill bit exist that can go through this cast? Possibly a cobalt (not the brand)?
If not point me in the direction of a proper machine shop that would be able to do it?
hum… a HSS bit should be able to do it no problem.
what kind of titanium bit were you using?
edit;
cobalt can do it as well although it’s more for stainless.
its a bosch titanium drill bit, it says 6x more life than high speed steel. So should i try a high speed steel instead?
---------- Post added at 08:02 PM ---------- Previous post was at 08:00 PM ----------
lowes / home depot should carry the cobalts right?
Use either, but run it slow, and use lots of cutting oil (or general engine oil if you don’t have cutting oil). My bet is you were running the bit too fast and without any lube; that’ll kill any drill bit.
well i was using oil, slow seemed to be much more effective than fast lol. but i figured the titanium would at least make a dent in it, but it barely took anything out
if you know how to resharpen bits, just grind it and retry.
if the bit is bent or worn to shit, cut it where it stops bending.
you more or less just want a 135 degree bevel on the bit, can use a bench grinder.
file off the sharp points on corners and presto good as new… just shorter… 
carbide bit in a dremel. Itll get the job done fast
If you are trying this with a hand drill you’re just asking for a pain in the ass.
At the very least, find someone with a drill press (and a vise) and your life will be much happier.
Like mentioned, slow, with cutting fluid.
You probably killed your bit (it can be resharpened) and if you’re unlucky, started to work harden your piece.
Changing the coating / material of the bit won’t make it cut any better, it will just allow it to have better wear properties (and as such, allow you to run at higher speeds).
Well I slapped a hss bit in the drill. And it seemed more effective than the titanium, or it could be my mind playing games. But I will go buy a few new bits tmrw and hopefully get it done
use a drill press. if you go in at an angle it will be all funky when you go to tap the hole or attach the turbo/adapter plate. plus if the hole ends up too big from the bit moving around the threads will always be loose.