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Fumbler
3rd February 2017, 07:38 AM
Team, what issues can anyone foresee (apart from using drill bits, and forstner bits) with turning between centres on a lathe with HEAD/TAIL Stock misalignment. I have had reasonable success with this being out of alignment (unbeknownst at the time). I discovered the alignment issue when I tried to make a bottle stopper mandrel / Screw chuck. When I drilled for the M8 bolt, it took a little while to figure out the issue when the bolt was sloppy. Not a Happy camper, I tell you.
Thanks to Willy, and another thread on here I have instructions and an exploded view pic of the lathe to adjust.

NeilS
3rd February 2017, 10:02 AM
One example: Yesterday I was working on a deep hollowed vessel and to turn that off its spigot I supported it at the tailstock end while parting it off. If the centres are not aligned the support at the tailstock end wobbles and the almost completed piece is at risk of failure.

On headstock/tailstock alignment; kissing centres (points touching) does not necessarily indicate alignment along the full length of the bed. Sighting through a hollow centre with the tailstock positioned at the far end of the bed is an additional check to ensure alignment.



Stay sharp!

Neil

Fumbler
4th February 2017, 04:44 AM
Thankyou, I also have found this whereby I release the tailstock and the piece then turns untrue and wobbles to all buggery.

when drilling I could always counter by using a smaller drill bit. if I need it 8mm i'll use a 7mm bit!! doesn't fix the overall problem though.

Fumbler
4th February 2017, 04:46 AM
I did also think that the bed may be warped or bolted down to a stand not dead true which is possible, although the bed does seem quite sturdy.

Paul39
4th February 2017, 08:50 AM
Sometimes there is some side to side slop between the bed rails and the tailstock. On my Hegner, I slide it up to where I want it then pull the tailstock toward me before locking down.

You might try pulling toward you and locking down, and pushing away from you and locking down. One may be closer than the other.

If it is off up and down, that gets more complicated.

If you have a movable headstock you could get some dirt or rust between the headstock and bed which would point it up or down, or not get it pointed straight down the bed. Dirt and / or rust between the base of the tailstock and and the bed could also cause misalignment.

You might start with taking things apart, cleaning, and lightly oiling.

NeilS
4th February 2017, 10:15 AM
I did also think that the bed may be warped or bolted down to a stand not dead true which is possible, although the bed does seem quite sturdy.
It may seem to be sturdy, but cast iron is slightly flexible. That is in part why it is used; it absorbs the vibrations.

My current lathe has both cast iron legs and bed, so the chance of twist is even greater.

I adjusted the alignment on mine by using shims while sighting through the headstock, as described above.

Stay sharp!

Neil