Hi,
If you stuck a 1" dia bar in a 3-jaw chuck so it protruded out by say 8" and took a 30 thou cut off of the farmost 6" what would you expect the turned diameter to vary by ? Lathe is a newish Super7 and the bar was not supported at all at the end furthest from the chuck.
Thanks,
Boo
10-20 thou larger at unsupported end perhaps?
If you want to test the run-out on the lathe take a 2 thou cut under similar conditions.
Bob
You should check the runout at the chuck jaws as well.
Jim.
it will be more if using carbide cutter rather than hss one, but the correct way for checking is to fully chuck, centre drill rechuck then setup your tailstock with a centre and do your test cut, 8'' inch hangout is a big ask of a little lathe for accuracy under the conditions decribed.
its potential accuracy or otherwise. This procedure is very bad engineering practice as I found out many years ago when I did my Toolroom apprenticeship. The bar could quite easily roll over the top of your tool with dire results. I did actually try to cut a fairly long slender job last week on a cnc lathe with massive headstock bearings without tailstock support but the result was predictibly rubbish so I then had to do it the correct way.
Best wishes
Tony Pratt
That depends on how well you have set the lathe up in the first place.
If you look > Hi,
Thanks for the answers, I know it's not a good test but that's the only piece of work I've seen from the lathe. From the responses it looks reasonable anyway.
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