Engineering and fabrication
Machining question, boring a small hole on a metal lathe?
I want to bore/drill a hole slightly less than 1/8" in diameter into aluminum about 2" deep, straight-through. What is the best cutting tool I would need to use and what is it called? I'm concerned that a standard HSS drill bit would wander and have a tendency to snap since I had that problem on a drill press... I haven't gotten into it yet, just anticipating problems, I'm new to machining.
Public Comments
- If your bit wandered in a drill PRESS (not a hand drill) then your bit was dull or your spindle speed was too slow. Run over 1000 rpm and use a sharp bit. If you insist doing it on the lathe you'll use the same bit. Metal lathes have a chuck that fits into the tailstock (where the deadstock/point usually is) and the chuck has acme thread and a wheel. Again, run your lathe fast, use a sharp drill bit, and use a steady speed as you feed the bit into the work.
- You are right to be concerned. It will be hard to do and harder to fix if the drill gets broken and won't come out.
Mount the drill so that only half an inch is sticking out of the drill chuck.
This is to stop the drill bit bending.
Drop the rotation speed down and put grease on the drill bit.
Penetrate a little at a time, backing off every few mm to clear the swarth.
Then when the drill is fully in the metal allow another half an inch of drill to be used.
If the lathe was perfectly aligned and you are boring into a cylinder, you could then reverse the cylinder and bore from the other direction. This would avoid having too much drill bit in the Aluminium, but it takes a good lathe to do this.
- The key here is to ensure your tooling is sharp, your tail-stock is in good condition and on centre and that your lathe can reach a high speed. Start by using a small centre drill to give your drill a starting point. Then change to your standard drill. Make sure the flutes on the drill will allow the hole to be made without being covered. If not, you will have to "peck" at the hole, i.e. Drill a bit, clear the drill then drill another bit. Be GENTLE! this is a relatively small drill, and it is unlikely that your machine will give you the normal cutting speed required for aluminium. Make sure the drill is tightly held in the tail-stock chuck, then ease it into contact with the work piece. Watch the swarf, if you have a good ribbon coming away from the drill, your speed is ok. More than likely you will get small scrolls. make sure they are clearing well. Then just continue like this until the hole is made, pulling the drill out every so often to fully clear the swarf. Depending on the dimensional accuracy you need, you may have to start with a smaller hole and then ream. similar process, but you finish with a reamer.
If you are still unsure, try on a few test blocks first to get a feel for it. If you keep breaking drills, you are being too heavy handed, if the drill is wandering, then it is either dull, or the tail-stock is out of alignment.
Good luck.
