Whilst a lathe should be supplied with a level of accuracy at purchase its not beyond the bounds of your average ME to tinker with his machine to improve it, since I've been on here posting many of you have successfully and displayed the fact, checking ovality of a piece is difficult enough but not impossible but it shouldnt be done with an inaccurate piece of equipment like a three jaw chuck, better its tested in a collet chuck etc.
As the quote ETW said our machines, and I include my Clarke CL500m, are a lot better made in design and accuracy and the ultimate accuracy should be in the hands of the man operating it, how many of us push the capabilities of our machines, for whatever reason, and then complain about the fact that the finish, taper and size is bad when we dont take notice of the forces we have just created have exceeded the design parameters of the machine.
Martin P