01-15-2013, 10:40 AM
Dave is right, you need a LOT more speed to get the finish better.
How fast does your lathe spindle go? Even at 2400rpm with a 1" bar of stock you're just getting into the recommended cutting speed for grade WPP20 on annealed 4140, so let 'er rip! It's just a guess, but it looks like you're running about 400rpm. If you're afraid to try it, start by upping it one step up at a time without cutting, just to see how it runs. You need to get a lot more heat in the cut to get a good finish.
How fast does your lathe spindle go? Even at 2400rpm with a 1" bar of stock you're just getting into the recommended cutting speed for grade WPP20 on annealed 4140, so let 'er rip! It's just a guess, but it looks like you're running about 400rpm. If you're afraid to try it, start by upping it one step up at a time without cutting, just to see how it runs. You need to get a lot more heat in the cut to get a good finish.