Centre alighnment

[Redtails3]

Hi
A simple question how do you align the centre's correctly on a swivel head lathe ?

[Les Symonds]

You do what's called a 'kiss-test'.

• put a drive centre into both headstock and tailstock
• move toolrest out of the way and bring the tailstock up, leaving a gap of a few mm between the tips of the centres
• swivel the head until the tips of the centres are very close to being lined up, lock the headstock
• wind in the centre in the tailstock quill to see if it 'kisses' the headstock drive centre
• if not properly lined up, wind the tailstock centre out a few mm and adjust the headstock a little
• lock the headstock and try the kiss-test again
• repeat the test until the two centres 'kiss'

Les

[Bryan Milham]

To add to what Les says, alignment on a wood lathe is not quite what it is on a metal lathe.

I find the only time it is frantically important is when end drilling, to be sure I get that right, I create a small recess in the centre of the timber with the tip of my skew so that the drill bit centers correctly.

Try this;

Deliberately offset your headstock by a few degrees and put a spindle between it and the tailstock livecentre, align your toolrest to the slightly skewed angle, you'll still be able to turn a parallel cylinder.

[The Bowler Hatted Turner]

Redtails if you are struggling to get correct alignment there is an alignment tool that you can buy (possibly from Axminster tools) it looks like 2 morse tapers attached to each other, one each end and all you do is put one in the head stock and one in the tails stock, loosen the head stock and wind out the quill, that will ?should force the head stock into the correct alignment.
           As dragonfly says it is not too critical on a woodturning lathe but if it is out it will wear the bearings quicker.
I hope this helps.

[Redtails3]

Hi
Many thanks for the relies I have had a think about this and have come up with a solution  get a bar twelve inch's long centred both ends and machined on these centre's put between male centre's  on the lathe, using a dial gauge  get both ends of the bar to read zero to zero with the dial gauge and bobs your your uncle.
Observations the longer the bar the more accurate the alignment will be.
If you use this way have the centre's proteced by a simple diameter cut into the bar.
The size of the bar wants to be around 15mm mom and hardened.

[fuzzyturns]

I am afraid I don't quite see how this makes Bob your uncle. The machined ends sitting on male centres will have oodles of play sideways, and unless you have a very precisely machined bed (which wood lathes generally don't) there's no way this will help with your alignment.
As far as I can tell (and I do have the very same issue with my lathe), the kiss test, a good visual alignment with two cone centres or the double morse taper are the only methods that really work. Sorry.

[Redtails3]

Hi
After much thought I came to the point about your statement fuzzy that there are two answers what ever method you use there is the question of the headstock alignment which should be addressed first.the second question is that the methods of bringing the two centre's together or using the double Morse taper they are useless because once you move the tailstock the alignment you had has gone so with your oodles of side play you have defeated the object of the exercise. See using my way you do not move the tailstock.

[Derek]

Probably get shot down for how I do mine that is to remove all attachments in the head stock, put a revolving centre in the tail stock bring this up to the head stock and loosen the swivel wind in the tail stock until it touches all the way around in the morse taper all lined up then tighten swivel head.

[fuzzyturns]

Since the tail stock on a lathe is moved all the time, you can safely assume that it will be well aligned with the centre axis of the lathe body. In other words, you are not aligning head stock and tail stock. You are only aligning the head stock. In consequence what I said earlier, still holds.
Derek's method should also work, if the inside of the head spindle holds a taper similar to the outside of the centre mounted in the tail stock.

[Redtails3]

If you draw a line down the centre's of your lathe, align the headstock and tailstock then
Move the headstock and swivel it around its axis say for example through 90 degrees then bring it back to its original position then check the alignment with the tailstock it will
Be out off the centre line and for every one inch or twenty five. Four of a millimetre it will
Multiply by its tangent.
And the same goes for the tailstock in reverse so along our line they pointing away from each other that's what's causes bearing failure and drills to cut oversize.

[Paul Hannaby]

If you draw a line down the centre's of your lathe, align the headstock and tailstock then
Move the headstock and swivel it around its axis say for example through 90 degrees then bring it back to its original position then check the alignment with the tailstock it will
Be out off the centre line and for every one inch or twenty five. Four of a millimetre it will
Multiply by its tangent.
And the same goes for the tailstock in reverse so along our line they pointing away from each other that's what's causes bearing failure and drills to cut oversize.

 
I understand all those words but unfortunately, not in the order you used them!

[Redtails3]

Paul
What is there not to understand the line is imaginary on a wood lathe you have no real ability what I am stating you have to factor in some.
Look at lathes that are of far eastern manufacture with a single ball or roller race at the front of the headstock if the weight of a wooden blank doing around with intermittent cutting taking place and now add the headstock and tailstock
Being out of  line how long do you think that bearing is going to last?
Even good quality double row ball and roller will not stand that abuse.

[Redtails3]

The line that states you have no should read "reparability"

[julcle]

I have to ask if this post is a wind up ?

[bodrighywood]

I have to ask if this post is a wind up ?

Seems a bit that way. Original question was answered in the first reply LOL. Rest is over my head 

Pete