Originally posted by scubaman
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This isn't April 1 any more, is it? Are you saying these spirals were made by 'chisel bounce'? Are you able to produce these at will, with no accessory, just by modifying the cut, or was this a one-time (happy) accident?
I'm not sure I follow your explanation, the tailstock end having the least support and most 'whip'. That's just not my experience. I know the effect, I didn't think it had to do with sharp or dull tools. When I've seen the spiral pattern it was with sharp tools. And once you got the pattern it's darn hard to get rid of it...
It really doesn't have to do with sharp or dull tools, but how hard you are pushing against the mandrel. Generally, with dull tools, there will be more force against the mandrel, causing it to bounce. The same thing will happen with sharp tools as well, provided there is sufficient force against the mandrel. I've never been able to cut the spirals on the headstock end - only the tailstock end, so both halves are turned on the tailstock end.
I cut the spirals with a top secret tool (cheap chinese made spindle gouge [
]). It's kind of like a reverse chatter tool. Instead of the blade of a chatter tool bouncing, the mandrel will bounce. Sometimes the pattern is better than others, but done at will, yes. Sometimes there is tear out, in which case, I just turn bushing to bushing (I won't take the time to hand sand all of those tiny spirals).