Proper tool position?

I got a newbie question. When using a left or right handed cutter do you situate it so that just the tip is touching the work or the whole length of the cutting bit? I read in a machining book where he angled the post so the whole edge of the cutter was against the surface but can't seem to find a tutorial that shows the proper way to use each cutter. Thanks.

Mike

Just the tip, and only ever the tip.

There's no practical way that you could set the bit such that the edge is precisely parallel to the X axis, without the risk of the tip itself being farther from the workpiece than the shank end. Besides, lathe bits will nearly always cut best with only the tip cutting- cutting on an edge can lead to some terrific chatter.

You need to get a basic machine shop text book. Check your local bookstore, Amazon or Ebay. They should be pretty cheap. The book should show you basic tool set up, speeds and feeds as well as other useful tips.

Tools are made or ground to be at 90 degrees to the workpiece (lathe). Otherwise you defeat the care that has gone into making them at the proper angles. Sometimes one adjusts the angle slightly to accommodate a special need. But normally one would grind a special tool to do so.

If you look at something like Machinery's Handbook you will find the accepted angles for the cutting tools.

Left/right and up or down angle and cutting tip alignment with the center of the spindle will greatly affect how well the tool cuts and the surface finish.

ever watch a brake laythe work? the tip of the cutting edge is what you want.
the least ammount of the cutting edge toutching the surface gives you the best results.
A finer finish and more percise