Sherline Owners, Advice tailstock alignment.

[paul gough]

Could owners of Sherline or Proxxon lathes advise on tailstock modifications they or others have made to achieve accurate alignment with the headstock. I have noted Luiz Ally's method via his 5 videos on youtube, but was wondering if anyone else has developed an alternative design. I am aware of the adjustable holders that Sherline can supply, but these seem to be a clumsy work around to overcome the inaccuracy. Regards Paul Gough.

[crueby]

I'd be interested in that too. Aside from turning the headstock, never found a way to adjust the alignment.

[Florian Eberhard]

Hi Paul and Chris

Well - I don't own one of those lathes. But i just looked at some pictures on google. There seems to be no way of adjusting the tailstock to the spindle actually.
I have found a movie though where a guy modifies his Sherline-tailstock to be able to adjust the alignment:
<a href="https://www.youtube.com/watch?v=7byihtwdks8" target="_blank">http://www.youtube.com/watch?v=7byihtwdks8</a>

I guess this is the only way to do it properly (although I would not cut a slot in the upper tailstock part). The same for the proxxon lathe, cutting the tailstock apart and make it possible to align it by moving sideways and up and down.

That should work pretty well because of the shape of those tailstocks.

I will need to do the same with a tailstock for my Schaublin that i bought additionally (and the alignment is not good) but that is going to a bit more complicated since those are made from a casting which is hollow on the inside.

Cheers Florian

[paul gough]

Thanks for your input Florian. The video you mention is from the You Tube series by Luiz Ally, (Tryally), I mentioned in my post. I too wondered about the 'slot', and thought there might have been an alternative, however overall it appears to be a good method as using the turned up morse taper test bar in the headstock ensures keeping the tailstock quill parallel to the headstock not just the alignment of the points on centres. I would be very interested to hear of or see any refinement of the Tryally design you or anyone might propose. Regards, Paul Gough.

[Florian Eberhard]

Hi Paul

Ah right, I didn't notice that - I guess i should read a bit more careful
Well I would not do it without measuring.
My way would be to take a ground bar with the according diameter (like they are used for guiding columns in punching tools - they ) and then insert that into the tailstock body. Then I would measure by moving either the tailstock or the saddle if that bar is straigt to the bed. If this is achieved, I would put the quill back into the tailstock and then, using a steady center and an indicator in the spindle measure how much it has to be moved in which direction.
Then swicht back to the ground bar and move it as required, using an indicator to move it to target. When this is done, I would repeat the measuring with the steady center again to verify and see if there is any deviation and probably go through everything again if it is out of what you want to reach.

What I didn't mention is that the main spindle has to be parallel to the bed too if you are going to do this! Otherwise you would get your tailstock right in one position only and not along the whole bed.

[paul gough]

As usual, your approach to achieving precision shows. Making sure all the components geometry is known so adjustment can be made for the best outcome is no doubt the superior method. I made assumptions that the level of manufacturers accuracy relating to the longitudinal axis of the headstock spindle, (when locked in position by the locating pin), and alignment with the bed ways would be within an acceptable limit, now I see this would need to be investigated as well. The old story, seeking to improve one inaccuracy leads to discovering something else that, potentially, needs attending to, also never make assumptions. However, for a reasonable fix the Tryally method seems to me to provide a way for those with only Sherline size equipment to re-machine and modify the tailstock etc. and significantly improve accuracy. Still, I am not a machine tool expert by any stretch of the imagination and if there is an alternative or better method then knowing of it would be great.     Again, thank you Florian for your input and alerting me to all (?) the parameters needed to get the best outcome, any further ideas on the tailstock body modifications would be most welcome. Regards, Paul Gough.