Thread: Grinding a Hardened Tailstock Bore

Bryan, I retract my comment about the difference between the sine bar and your set-up. Upon reflection I realise now that that if you indicated the workpiece along its length at zero then it truly must be coaxial with the lahe's spindle when the TIR at the both ends is also zero.

Great use of the Falconio part too-I forgot that they were in fact Fiat derived

Originally Posted by Bryan

Ewan, thank you for fielding Greg's cheek. Do you consider an AU plastic trash? That's what I'm driving so that's what I had on hand.

I know its a bit off topic but it just annoys me that modern cars have no fixable parts, the bearings are pre lubed and sealed, gearboxes the same. I know its all about less time for the mechanics to fix, but our throw away society is getting a bit out of control in some industries.

I'm guessing the au still has "real" bearings, so i guess its not trash....

Ewan

Originally Posted by Bryan

I figure if I can first prove the alignment of the TS chuck axis with the HS spindle

Yes but how are you going to do that?
Turning a test piece wont do it as you'll be offset horizontally to make up for any vertical error.(ok granted not much!)

Regardless of how badly aligned the steady is, it will try and hold the workpiece at 0 run out. If you loosen the steady off so the work piece is just held in the chuck, you are then checking both ends against the spindle axis. You don't have to worry about the DTI being on center height or even having the same number both ends, just 0 runout.

Originally Posted by Greg Q

Upon reflection I realise now that that if you indicated the workpiece along its length at zero then it truly must be coaxial with the lahe's spindle when the TIR at the both ends is also zero.

If the ways are parallel to the spindle axis.(of course if it isn't setting up the angle will be a problem)

Wanders off wondering if I'm trying to build a binocular telescope when the bottom of a coke bottle would do??

Stuart

Sorry, quite correct. I Ass-U-Me-d that had already been verified on this machine. But, as you say, if the ways aren't parallel to the spindle's axis then there are bigger fish to fry. Its odd that I thought I'd take up this caper to relax!

As a practical matter, this would be a good job for a king way alignment tool to verify the ways' relationship to the spindle axis, both laterally and verticaly.
GQ

When I returned from my first scraping class in the US the whole flight back I dreamt of randomly aligned lines in infinite 3D space with only a level and deductive reasoning to sort them out. I was grumpy on arrival.

Originally Posted by Retromilling

To set a normal cross slide taper attachment to a fine degree is not so easy .
Although it can be more rigid in some respects but also it can suffer from other vibrations across the line of cut .
It is possible to set the compound to a fraction of a degree with a sinebar setting gage and software that is already presented in this forum in other threads by me .
If the compound dovetail is adjusted properly to be tight and slop free even with the compound hanging over a bit it is no more problematic as to vibration or slop than the normal taper attachment is and the carriage can be locked . If you start with the compound back somewhat in the short distance of a MT4 it should not hang over much depending on how large it is to start with . I think the compound is likely to be more rigid than the tool post grinder itself . Excellent short tapers can be cut just using the compound but finish may not be as consistent as using longitudinal feed of the carriage . Once the taper is too long for the compound to cut it all becomes academic.
To set a really accurate taper on a normal cross slide taper attachment requires some fine measuring or using a dial gage to dial in on an existing taper . However with the sinebar function compound setting gage once a taper setting ring or block is made you never need to measure anything again to setup for that taper.
While you are messing about with disconnecting the cross slide and or dialling in a taper I will have finished turning the taper . The compound setup takes seconds once you have the correct ring Gage or block made.
Most hobbyists will only need short tapers.

Thanks retro.

Originally Posted by Greg Q

. Its odd that I thought I'd take up this caper to relax!
.

Relax! I read a comment somewhere a while back where it was considered the activities of the machinist and mountaineer were alike. Both planned the next move to avoid disaster.

BT

Originally Posted by Stustoys

Yes but how are you going to do that? [align TS to HS]

I've been trying all morning and it's not as simple as it sounds.

If you loosen the steady off so the work piece is just held in the chuck, you are then checking both ends against the spindle axis. You don't have to worry about the DTI being on center height or even having the same number both ends, just 0 runout.

What's that sound? I think... yes it's my head getting slapped And if I chuck it shorter I may not even need the steady. I seem to have conditioned myself to think there are only two proper ways to set something up in a lathe - short or long. But for grinding or other light work, 'medium' may be just fine. Oh well, the live chuck will have other uses. Great for setting up a steady so you can centre drill long stock that won't fit through the spindle. Thanks Stuart.

This is getting very time consuming glad no ones paying.

Don't worry PC it could well be saving money, just imagine what we'd be getting up to if we werent talking about this? I always tell the boss "its cheaper than golf"


"I dreamt of randomly aligned lines in infinite 3D space with only a level and deductive reasoning to sort them out" This I do a lot, just that I dont always come up with the right answer lol

I dont recall how the kingway deals with the spindle axis, I'll have to dig out the thread again.


Stuart

Originally Posted by pipeclay

This is getting very time consuming glad no ones paying.

No need for you to waste any time on it.

I just enjoy reading all the different allternatives and thoughts that people throw around,and think I must of missed out on a hell of a lot over the years.

So how would you do it?

I would go over to HSM and ask a certain poster over there how to do it... I am sure you would get a reply complete with spec sheets and photo's of machines....

I wouldnt worry about using the outboard chuck.

I would setup with 4 jaw and steady.

As soon as you start to set the steady up any concentricity or trueness would be lost I believe.

The loading from the steady fingers would be enough to throw it out.

It would need to be set true using the steady at the outer end.

You would need to keep setting between the chuck and steady untill true.