Tangential tool

I have a Super 7 and am using a tangential tool and holder (commercial) which leaves a rather rough surface cutting towards chuck, but leaves a lovely smooth surface on the return journey towards tailstock. The tool has been recently sharpened in the jig so I am obviously doing something wrong.

Despite this I have just turned a length of MS to within 0.0003" of the required size.

Some help, please?

Many thanks in advance.

Richard.

If it's cutting on the return journey without putting on any more of a cut then something is moving about when it should not.

I use a homemade tangential tool a lot of the time and find that the orientation of the tool needs to be changed to get the best cuts.

Are you cutting with side and face clearance in your orientation? It's easy to have the trailing edge rubbing which won't help the finish?

The other thing is that there are two cutting edges behind the top and perhaps only one of them is truly sharp?

Just some things to check. I hope this helps

Jon

Is the tool cutting on centre? I use a home made Tangential tool and don't have any problems with surface finish.

Some thoughts come to mind, the supplied jig is not necessarily of the best design and, if used with too coarse a wheel, might not sharpen both cutting edges equally. The supplied jig is a compromise design for both turning and threading and because of this it tends to put striations along the length of one of the cutting edges which will not be as sharp as the other. A 30 degree vee shaped jig held at right angles to the wheel is, in my view, to be preferred as it puts an equal grind on both edges.

Another thought is have you put enough of a radius down the length of the tool bit. A sharp corner does not seem to cut as well as a radius one. If you put different radii on opposite corners and sharpen both ends you can select the either end for different needs.

A tangential tool will often give a superior cut on the back stroke, due to a sheering action, but should still cut forwards almost as well if ground well..