Thread: my new AL960 cutting a taper

Hi Eskimo,
Sounds like you've done a great job.
Did you loosen the middle bolts right off or leave them tightish when making the adjustments?
RDM? Relational Database Mining?

Stuart

I kept that one firm..and to the opposite end to the one I was adjusting

RDM...Rollie"s Dad's Method for aligning the lathe

You can't really give Rollie's dad credit for this one. You were aligning the headstock to level(untwisted) ways. As I understand it Rollie's dad's method is really about twisting a level lathe to make it cut straight(parallel).

Stuart

Thanks for the description, Eskimo. This thread, and in particular RC's post -

Originally Posted by .RC.

Also I think the two collar test is really only applicable on light short bed lathes like a Hercus... Not a lathe that is metre between centres..

That is why I would precision level it to remove twist...... Then adjust the headstock to suit..I have adjusted the headstock on two lathes now... it is not hard, just time consuming..

got me thinking and mucking about with my AL960. I have got it cutting parrallel but the bed is slightly twisted to achieve this. So I conclude that my headstock is misaligned after all. The smart thing to do now is leave it alone because it is doing the job, but the perfectionist in me wants to start on that headstock. .....

Graham

Good work Eskimo, Now was the lathe leveled spot on before you did this?

It has always been recommended to use a large diameter thick wall pipe to take a test cut on. This way it's still nice and rigid 200mm+ out from the chuck.

You will need to check how it faces now and see whether it a faces concave or truly flat.

Dave

Hi Eskimo,

Just caught up on this thread. The taper of 0.0001", was that over the length of 18 inches?

My god I have a lot to learn! I was puffing my chest out when I got my lathe to turn 0.0001" in 6 inches!

Simon

Originally Posted by Dave J

Good work Eskimo, Now was the lathe leveled spot on before you did this?

It has always been recommended to use a large diameter thick wall pipe to take a test cut on. This way it's still nice and rigid 200mm+ out from the chuck.

You will need to check how it faces now and see whether it a faces concave or truly flat.

Dave

Hi Dave,

How flat does truly flat have to be? Don't all lathes turn slightly concave, albeit very small?

Originally Posted by simonl

Hi Dave,

How flat does truly flat have to be? Don't all lathes turn slightly concave, albeit very small?

Hi Simon
They should cut concave and no more than about 0.02 / 300mm seems to be the maximum from manufacturers. As for truly flat it was just the way I worded it.

Dave

Originally Posted by Stustoys

You can't really give Rollie's dad credit for this one. You were aligning the headstock to level(untwisted) ways. As I understand it Rollie's dad's method is really about twisting a level lathe to make it cut straight(parallel).

Stuart

I think what RDM does is establish what you might call a proxy for the spindle axis. And I think aligning a headstock to a straight bed is a far better use for it.

Originally Posted by GDD

I have got it cutting parrallel but the bed is slightly twisted to achieve this. So I conclude that my headstock is misaligned after all. The smart thing to do now is leave it alone because it is doing the job, but the perfectionist in me wants to start on that headstock. .....

Graham

I disagree about leaving it alone being smarter. A twisted bed is not what you want, except maybe as a last resort on a worn out lathe.

Yes ,not seeing any significance in what method was used to hold work piece was the reason for chuck question.

Hi Graham
I agree with Bryan and think it would be time well spent trying to align the headstock as good as possible with the lathe perfectly leveled.

I went through your posts to see what lathe you had as there are that many members with different machines it's hard to remember them all, and see you have had it for 18 years. I am not sure how much you twisted it or how long ago but if it was twisted a bit and long ago it might have a permanent twist to it now. If it was something done in recent years you should be able to get it back.

You have a fail safe if you get into trouble, Eskimo will come around to do it for you as it's a 5 minute job to him.

Dave

Originally Posted by simonl

Hi Eskimo,

Just caught up on this thread. The taper of 0.0001", was that over the length of 18 inches?

My god I have a lot to learn! I was puffing my chest out when I got my lathe to turn 0.0001" in 6 inches!

Simon

no Simon
it was .0001 over only 2 inches...so still leaves room for improvement if yours is doing that over 6 inches

I might have another go later when I have more time

Originally Posted by Dave J

Good work Eskimo, Now was the lathe leveled spot on before you did this?

It has always been recommended to use a large diameter thick wall pipe to take a test cut on. This way it's still nice and rigid 200mm+ out from the chuck.

You will need to check how it faces now and see whether it a faces concave or truly flat.

Dave

I had leveled the lathe across the bed at both ends..I reckon about .00025 difference going the bubble..is that good enough?

My material was only short Dave, but non the less better than what it was

So should I follow you guys opinions and do it on a longer piece further out from the chuck and over a longer piece?...what should I be striving for...Simon says his does .0001 over 6 inches..is this my target or should I have a target of say = or <.0001 over 8 inches ( with out tailstock support ).... and would that also be at 8inches out from the chuck?

Originally Posted by Stustoys

You can't really give Rollie's dad credit for this one. You were aligning the headstock to level(untwisted) ways. As I understand it Rollie's dad's method is really about twisting a level lathe to make it cut straight(parallel).

Stuart

yeah..but the method of measurement still works doesnt it?

doesnt matter now cos it cuts .0001 over 2 inches.. but going by Simon his does better than this so maybe back to measuring some more eh?