The correct way to check accuracy is to use a test bar that matches your
spindle bore. Mount the bar and test for taper with a tenth indicator, first
on the bar top then on the side. This checks the headstock alignment with
the ways. A precision level (.0005" per foot per scale division) is needed
to check for bed twist and wear. This should be done without carraige,
headstock or tailstock.
Steve
"Martin Perry" wrote in message
om...
I have an old Boxford lathe. The bed shows signs of wear but otherwise
it is in excellent working order. Everything works smoothly without
any undue slack.

I checked the accuracy the other day by turning an eight inch length
of two inch diameter bar. There was a slight taper on the finished
work. The bar was 0.001 inches smaller nearest to the chuck.

I then bored a two inch diameter hole in a four inch diameter bar and
found that the bore was 0.001 inches larger nearest to the chuck.

These two errors seem to be in opposite directions. Can anybody
suggest an explanation please.

Regards, Martin Perry