Post by engineeringtech on Jun 23, 2008 19:37:11 GMT
Hi-
Need some advice on turning drill rod, in particular O-1 oil hardening and S-7 shock resistant air hardening material.
I turn a fair amount of precision pins on a secondary operation lathe. Usually I use leaded steel, like 12L14, which is still allowed in the states. It gives a very clean finish very quickly, and tools do not get dull very fast. I can cut to .0002" (.005 mm) tolerance all day long with this material. I very seldom use tool steel, because the pins I make don't need to be hardened.
I am making some pins today from O-1 and S-7 Steel. Even with a brand new insert in my cutter, I get a bad finish on my parts. And I am not cutting to size. If I take a fine cut (.005" or .1mm), measure, then another equal depth fine cut, my machine will miss by a couple thousandths. It will be over OR undersize. In other words, depth of cut is not repeatable. The finish will be smooth for part of the turning, then go rough, then smooth, etc. Almost as if there are variations in the material itself. I do not have a power feed on my machine, but I have been very consistent about operating the handwheel. I also believe I am using an appropriate spindle speed and feed for 1/4" (6mm) stock) (about 900 RPM). I do not have flood coolant on this machine. I am using a new micro lubrication system, that sprays a fine mist of vegetable oil. The part does not seem to be getting hot, and the chips are not changing color. The cutter does not seem to be getting a buildup on it. You can see that the chips are being intermittently interrupted. The insert is a general grade of carbide and the problem persists if I switch back to HSS.
Any ideas? Maybe my machine is too light duty, and is moving on me?
Need some advice on turning drill rod, in particular O-1 oil hardening and S-7 shock resistant air hardening material.
I turn a fair amount of precision pins on a secondary operation lathe. Usually I use leaded steel, like 12L14, which is still allowed in the states. It gives a very clean finish very quickly, and tools do not get dull very fast. I can cut to .0002" (.005 mm) tolerance all day long with this material. I very seldom use tool steel, because the pins I make don't need to be hardened.
I am making some pins today from O-1 and S-7 Steel. Even with a brand new insert in my cutter, I get a bad finish on my parts. And I am not cutting to size. If I take a fine cut (.005" or .1mm), measure, then another equal depth fine cut, my machine will miss by a couple thousandths. It will be over OR undersize. In other words, depth of cut is not repeatable. The finish will be smooth for part of the turning, then go rough, then smooth, etc. Almost as if there are variations in the material itself. I do not have a power feed on my machine, but I have been very consistent about operating the handwheel. I also believe I am using an appropriate spindle speed and feed for 1/4" (6mm) stock) (about 900 RPM). I do not have flood coolant on this machine. I am using a new micro lubrication system, that sprays a fine mist of vegetable oil. The part does not seem to be getting hot, and the chips are not changing color. The cutter does not seem to be getting a buildup on it. You can see that the chips are being intermittently interrupted. The insert is a general grade of carbide and the problem persists if I switch back to HSS.
Any ideas? Maybe my machine is too light duty, and is moving on me?