Tim,
When I get the phonographing effect you describe on my Craftsman lathe with mild steel, I have had good luck by reversing the feed direction on the last cut. I usually take 2-3 thou off with HSS bits for the finish cut and the carraige traveling under power towards the headstock. I disengage the halfnuts at end of cut, turn off the lathe, reverse the tumbeler lever so the carraige goes towards the tailstock, turn on the lathe and then engage the halfnuts. This is done without touching the depth of cut. Doing this seems to take the "threads" off because the carriage is being pushed by the other side of the lead screw and is not in the same position relative to the work and the tool takes off the high spots.
The other option is leaving a couple thou to file or sand down.
Greg
When I get the phonographing effect you describe on my Craftsman lathe with mild steel, I have had good luck by reversing the feed direction on the last cut. I usually take 2-3 thou off with HSS bits for the finish cut and the carraige traveling under power towards the headstock. I disengage the halfnuts at end of cut, turn off the lathe, reverse the tumbeler lever so the carraige goes towards the tailstock, turn on the lathe and then engage the halfnuts. This is done without touching the depth of cut. Doing this seems to take the "threads" off because the carriage is being pushed by the other side of the lead screw and is not in the same position relative to the work and the tool takes off the high spots.
The other option is leaving a couple thou to file or sand down.
Greg
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