Thread: Headstock alignment

They are not adjustable as if done correctly at the factory, they never need adjusting..

If they are out then as far as I know it means one of three things.

A. It was never fitted properly at the factory.

B. It has had one hell of a crash in it's life.

C. The bed is twisted/out of level.

D. bearings??

Was it twisted or just not in alignment? What checks did you do? And as Stuart once said, did the headstock ways look like it had been attacked by and angry mouse with an angle grinder? Some of the Chinese scraping is pretty rough.
Having just pulled the LeBlonds headstock off, it has clearly been scraped neatly and presumably to alignment.

My three previous lathes had adjustable headstocks, so I assumed it was standard practice to provide some adjustment means, I guess not... It's a new lathe so obviously the machining was off, the V slot in the headstock had a better line up than Bell's Beach, but a little elbow grease smoothed that out a little and gave me just enough movement to true it up.

Perhaps it wasn't seasoned properly after it was cast and before it was machined?

Simon

Originally Posted by tongleh

My three previous lathes had adjustable headstocks, so I assumed it was standard practice to provide some adjustment means, I guess not... It's a new lathe so obviously the machining was off, the V slot in the headstock had a better line up than Bell's Beach, but a little elbow grease smoothed that out a little and gave me just enough movement to true it up.

Never try to align the headstock, before the bed is carefully levelled with a precision level. If the alignment seems off, in most cases the reason is simply a twisted bed. First make 100% sure your Headstock is really off - it is rare to be off without a clear reason like a collision or a transport accident.

If a lathe has an adjustable headstock, it is usually intended only for the adjustment at the factory during assembly. In the field, the headstock alignment is indeed a VERY difficult alignment to get right. The cheaper the lathe, the harder this alignment is. And the longer it takes. This is so, because in the field you cannot simply select from a pallet full of tailstocks, the one that suits your headstock center height AFTER having adjusted the same center line parallel to the bedways. And you will find that it is near impossible to align the headstock vertically and horizontally parallel to the ways without affecting center height. That is why good lathes do not have an adjustable headstock, they rather have it carefully scraped to the bedways so that no alignment should be necessary after disassembly in the field.

Proper headstock alignment is only possible with a perfectly level bed. Owning a precision level and a test bar that fits into the headstock taper are indispensable prequisitions for this alignment. It cannot be done without. The "rollie's dad" method will not work instead of a proper test bar, because the "rollie's dad" method is a simplification that only functions IF the headstock alignment is known to already be correct. And you will find that the HS alignment is so sensitive, that you must employ a "torque shimming" technique in addition to shims.

Before venturing any further, before undoing your HS bolts and pontentially undoing its alignment, please tell us how do you know that your HS is misaligned? Did it have a serious accident like fallen from a truck or the like? You see, some unexperienced people simply face a large diameter workpiece, and if this face is concave they wrongly conclude that the headstock is misaligned. But that is wrong, the cross slide dovetails in the saddle of a new lathe are on purpose slightly angled to ensure the lathe faces slightly concave, and never convex. If you check with a lathe inspection record, you will find that the tolerance for facing is offset, with a remark like "concave only". The reason for this is that if you assemble two flanges turned on a good lathe, they are slightly concave and cannot rock. If the two workpieces were made on a lathe that faces convex, the assembled pieces would rock. That is why a lathe that faces convex is regarded as a reject machine that cannot be sold with an inspection record.

Chris

Originally Posted by cba_melbourne

... the cross slide dovetails in the saddle of a new lathe are on purpose slightly angled to ensure the lathe faces slightly concave, and never convex. If you check with a lathe inspection record, you will find that the tolerance for facing is offset, with a remark like "concave only".

As per test no9 in this lathe inspection report.

And here I was thinking that the memebers had been pretty gentle hinting that maybe realigning your own headstock when you possibly didnt know what you were doing, might not have been the smartest thing to do.

Bye

Stuart

Just for anyone searching, after thinking about this issue of alignment, this is what I would do. The lathe in question is a pretty new smaller h&f machine, that would still be under warranty. I would check the lathe for level and then make test cuts. If the machine was cutting a taper I would check it against the inspection report, and take my findings to h&f. They should do something about it, if not put it all over utube etc......

[QUOTE=Ueee;1578263The lathe in question is a pretty new smaller h&f machine, that would still be under warranty. [/QUOTE]

Do the smaller chinese lathes (or even the larger ones) have the headstock sit on the V's?

I will say that all the ones I have seen all sit on flats, as it is cheaper to produce...

This sitting on the V's seem to be predominately a US thing...

Originally Posted by .RC.

Do the smaller chinese lathes (or even the larger ones) have the headstock sit on the V's?

I will say that all the ones I have seen all sit on flats, as it is cheaper to produce...

This sitting on the V's seem to be predominately a US thing...

They sit on the flats.

On good quality lathes like the Austrian made EMCO's, the bottom of the headstock is ground. Recesses are milled into the bottom to provide clearance for the Vee way (to make sure the headstock does not even come close of touching thye Vee). There are four studs in the bedway to bolt the headtock down. And there are 4 grub screws in the headstock, that can push sideways onto the above studs. This makes for a relatively easy adjustment horizontally. The vertical adjustment is done by "torque shimming", meaning if you torque the two hold down bolts at the right of the headstock slightly harder, the headstock center line will slightly rise at the tailstock side. Sometime this torque shimming is not enough, that is when a piece of cigarette paper or two can be used as a shim. Or alternatively, some strokes with a scraper can be strategically applied to the bottom of the headstock. But the problem remains, after aligning for parallelity with the bed, the tailstock center height may be off. That is why the 4 headstock holddown nuts should only ever be touched when there is really no other option and is 100% sure there is an alignment problem.

On less well made lathes, such as the countless China made copies of the Austrian Emco, the bottom of the HS is roughly milled, not ground (maybe it is on the larger 11" lathes, but definitely not on the 9" swing). Also the 4 adjusting grub screws are not always present. Sometimes a few are present. And if they are present, they were always drilled with a handheld drill during the assembly procedure, sometimes angled some 45 degrees downward to provide height adjustment. Needless to say, this practice does not help rigidity at all. Sometimes newspaper strips are used as shim. It really completely depends which factory, and which person does the assembling. I can only recommend one thing: if one buys a chinese lathe, level the bed and do the alignment test cuts. Compare to the inspection record. If off, return the lathe and demand an exchange. If the lathe does not come with an inspection record to begin with, well then it means it was sold as a reject lathe for probably very low price, and you are on your own to try to align it properly. You get what you pay for.

Chris

Originally Posted by cba_melbourne

On less well made lathes, such as the countless China made copies of the Austrian Emco, the bottom of the HS is roughly milled, not ground
Chris

I have seen Chinese lathes where the underside of the headstock was in fact ground, the only problem being that they used an angle grinder.

I am very interested in this thread,
I too have a lathe with a suspect mis aligned headstock, It will turn a 3 thou taper 4 inches out from the chuck or collet.
The lathe was purchased new, [al960b] no crashes and it has not been abused.
Ted

Originally Posted by TED C

I am very interested in this thread,
I too have a lathe with a suspect mis aligned headstock, It will turn a 3 thou taper 4 inches out from the chuck or collet.
The lathe was purchased new, [al960b] no crashes and it has not been abused.
Ted

You may have to put a test bar into the taper of your spindle and check to see if it is true too the carriage traverse with a dial indicator.
If no test bar then a piece of centreless ground bar or similar held in your 3 jaw should be fine.
There should be provision to adjust the headstock at the rear near your motor mounts,there may also be hold down bolts at the gap end and also at the change gear end.