This is posted more to solicit information than as guidance- this is what I did because I am concerned in that the last few times I have tried to turn a length of rod I have been getting a considerable taper. I've not got exact measurements although I will add these if the problem persists. I've been running the rod between the head stock chuck and a live centre in the tailstock- having previously centre drilled it to take the centre. There are several potential causes for this- the simplest is operator error and blunt tools which may well apply in my case, but it seemed sensible to check the alignment anyway. The tailstock is adjustable and could be twisted off line (even though the indication markings suggested that it hadn't) or the ways themselves might be twisted or warped.
I checked the ways first with an inclinometer and I found then level across and along- it surprised me that my setup was this resilient! Anyway the next step was simply to see if the head and tail stocks are aligned and to do this I removed the chuck.
Three 14mm nuts- space is tight so you need to pull the chuck forward as you undo the nuts evenly
The chuck then just pulls off- note that there are orientation markings on the chuck and spindle flange to make sure its refitted in the correct position.While the chuck was off I stripped the jaws and cleaned them and their grooves.
Having removed the check the MT3 taper was visible in the spindle centre- it was a bit dirty with swarf so I cleaned it and..
installed an MT3 centre.
I put an MT2 centre in the tailstock
Sadly I couldn't get the head and tail stocks very close because the carriage is in the way so I got them as close as I could and then locked the tailstock to the bed and extended the quill.
Bringing the centres close together before tightening the quill locking nut and checking the alignment by eye. This is obviously an extreme position and it would be better to check them with less extension, but at present I can't quite see how to do that. Maybe I can remove the tailstock and refit it the other side of the carriage? It seemed to me that there was pretty much perfect alignment laterally although possibly some misalignment vertically. This I am led to believe is acceptable. One test for alignment is to trap a piece of thin steel between the two centres and if aligned this should take up a vertical position at 90 deg across the ways.
This also appeared to be OK- I may need to use a thinner test piece but in any event it seems that my alignment isn't way out.
I could find no obvious looseness in the compound...
...cross slide or carriage.
Overall I am left mystified and unsure if I have a problem or not in the lathe itself. I will do some more test cuts using an unsupported bar and look at any tapering and then try taking a cut both with centre support and the moving steady to see if these make a difference. If necessary I will see if I can borrow a tailstock alignment test bar. Perhaps just cleaning the chuck jaws will have helped?
Any ideas out there??
