lathe alignment - again

Thanks for sharing. This is a very clever method, no cutting needed. The rod just need be reasonably true round at the ends, it can be bent or tapered. Just tried it on my lathe and happy to see that the alignment is close to perfect

Edited By Y C Lui on 07/02/2022 02:21:57

I cannot imagine DRO being off-cal by as much as that. Comparing the DRO reading with the hand wheel scale reading should give you some good idea on what's happening.

Edited By Y C Lui on 07/02/2022 02:53:01

Taking on-board all of the very helpful responses, I have been able to make a huge improvement today. I started by removing the chuck guard and reducing the length of bar extending beyond chuck jaws to 120mm - note I carried on with my 25mm steel bar as haven't procured any Aluminium yet. I then made a very fine cut again using the carbide tool, as that is all I bought with the lathe - result this time was 1 thou difference (larger at tailstock again), versus the 6 thou yesterday. As was suggested bar length / flexing was clearly having a major impact. I then eased off all of the mounting bolts (6 off), and left for an hour for the bed to relax; there is indeed a small gap on the front tailstock mount, which is consistent with the larger tailstock end diameter on the test bar. I then turned another test bar, and now am struggling to measure any significant difference using my old Imperial micrometer with 1 thou graduations, if anything it is in the region of 0.1 thou. I think I have gone as far as I can with steel bar, carbide tools and a mechanical micrometer with 1 thou grads. So, all good to use now, will check using the other methods / materials suggested in due course. Thanks again to all who replied with great advice - watch out next for naive questions on work holding! Steve

Great result! Put a shim under that front tailstock mount and bolt her down and you should be good to go. If you can't measure any difference with a 1 thou mike, all is well. No need for anything fancier in the home workshop. Carry on lathing.

Hi Hopper, all sorted and now ploughing on with Harold Hall's 'Lathework A Complete Course', and when done I think I will be ready to take on my Stuart Oscillator kit. Thanks again for your very helpful guidance, Steve