I have spent a very frustrating day in the workshop.

My 1974 Chipmaster has always given me acceptable to very good results depending basically on the material being turned. Its original 3-phase motor is inverter driven.

On checking for taper, I measured less than .0015" over a 6" length of freecutting MS 1.75" dia, not supported at the tailstock, using a .005" cut and .003"/rev feed. The tool was an HSS knife tool.

As the narrow part of the test bar was getting close to the measuring surfaces, I decided to take .020" or so off.

With a brazed carbide tool and a .010" cut at about 400 rev/min I was rewarded with a ploughed field of the herringbone persuasion.

Checked everything – gibs, slideway oil, chuck cleanliness and tightness, toolpost tightness, tool height etc.

Tried an HSS tool and slower speed – very slightly better but not acceptable.

Tried an insert tool and approx 800 rev/min and the finish was acceptable.

My preference however is to use HSS tools and low speeds/feeds.

Any suggestions gratefully received.