I am trying to drill a 1 1/4" hole thru a piece of aluminum. Any ideas on what type of bit to use. I couldn't find any metal bits that were small enough for my drill press.
TRKYHTR
you need a 1 1/4" hole saw. Can be found at most any hardware store, the orange or blue home improvement stores, or possibly the plumbing supply. They are used mainly for wood boring but aluminum is soft enough it should be no problem.
That was what I thought. So that was what I used. 30 minutes later the aluminum was so hot you could have cooked an egg on it and it still wasn't thru and it was a brand new hole saw.
TRKYHTR
I have been a welder and machinist for over 25 years now and have tigged and drilled enough aluminum that I will probably end up with alzheimers from exposure to it.
You need to drill aluminum slow.
Slowest speed yer press will go or one up from it.
Use a nice sharp hole saw and some tap magic, a thinner thread cutting oil or even wax.
The trick is to go slow with light pressure letting the bit do the cutting and not forcing it to cut.
Aluminum gets gummy when it heats up and clogs up the teeth.
Back the bit off periodically, clear the chips from the cut, give another little squirt of cut fluid and have back at it.
Go sharp and slow with some cutting fluid and youll get er done in no time.
Thanks for the help. Thats my problem. I need to have more patience and slow down. Why does that word always keep coming up?
TRKYHTR
Years ago I worked at a company that built controlled descent systems made of cast aluminum. As was stated, we drilled these cast aluminum blanks at a very slow speed. We used plain rubbing alcohol to cool our bit and reamer. You will likely want some sort of hold-down jig or clamp to keep your stock in place.
155 rpms lot of lube an no issues
Luke95