Why would someone put a 0.1mm shim under a Hardinge HLV headstock ?

[max.levesque]

I removed the headstock of my newly aquired 1956 Hardinge HLV-BK, and there was a 0.1mm brass shim between it and the bed.

I've read about many instances of elevating the tailstock after a bed grind, can't think of a reason to elevate a headstock, other than wanting to align to an elevated tailstock, but what in the world would elevate a tailstock ?

Unfortunately I haven't measured the spindle to tailstock alignment before removing the headstock (nor before buying), that information might have provided some explanation as to why the shim is there.

I'm going to put it back without the shim, put a dead center in the tailstock, and see how it aligns to a pin held by a 5c collet.

If the tailstock happens to be 0.1mm higher, it will explain the shim, if the heights turns out equal or lower, then I will be even more puzzled !

 

[MCritchley]

Perhaps tailstocks were switched at some time and this headstock was low.

A good check is to turn a piece the same diameter as the quill and do some indicating.

Do not attach an indicator to the chuck to sweep the quill, there will be sag. Mount an indicator on the carriage and go back and forth from your turned bar and quill.

 

[max.levesque]

Ok, I put back the headstock, with the shim, and the tailstock deadcenter align perfectly with a pin held by a 5c collet in the spindle.

The shim is there for a good reason. I'm still curious as to when the shim was added, and why.

The tailstock has turcite under it, I believe it's the cas for all HLVs, so it doesn't explain it, perhaps for some reason a previous owner wanted athicker layer of turcite and compensated with a higher headstock ?

I removed the headstock of my newly aquired 1956 Hardinge HLV-BK, and there was a 0.1mm brass shim between it and the bed.

I've read about many instances of elevating the tailstock after a bed grind, can't think of a reason to elevate a headstock, other than wanting to align to an elevated tailstock, but what in the world would elevate a tailstock ?

Unfortunately I haven't measured the spindle to tailstock alignment before removing the headstock (nor before buying), that information might have provided some explanation as to why the shim is there.

I'm going to put it back without the shim, put a dead center in the tailstock, and see how it aligns to a pin held by a 5c collet.

If the tailstock happens to be 0.1mm higher, it will explain the shim, if the heights turns out equal or lower, then I will be even more puzzled !

 

[michiganbuck]

I would suspect that someone wanted to level the tailstock and used a certain size turcite, and then shimmed up the headstock to match.

Very likely the tail was nosing down on a 1956 machine.

 

[Mark Rand]

Small point of order:- That bed's from an HLV-H, not an HLV.

 

[max.levesque]

Based on what ?

Everything about the lathe (even the serial number) is HLV (non H): dovetail is just under 5" wide, screws to bed from inside the headstock, etc...

Small point of order:- That bed's from an HLV-H, not an HLV.

 

[Mark Rand]

Based on what ?

Everything about the lathe (even the serial number) is HLV (non H): dovetail is just under 5" wide, screws to bed from inside the headstock, etc...

Sorry, brain fart on my side.

I hadn't realised that they changed the design in the HLVs and was basing the comment on my (1952) model, which has the headstock clamped to the dovetails (I can see why they changed it!).

On that point, have you checked to see if there is a shim under the bed plate as well? Only reason I could think of for that, would be wear in the carriage traverse pinion (which does wear, quite severely).

 

[gbent]

Do not attach an indicator to the chuck to sweep the quill, there will be sag. Mount an indicator on the carriage and go back and forth from your turned bar and quill.

Sag could be precisely why the previous owner shimmed the headstock.

 

[max.levesque]

On that point, have you checked to see if there is a shim under the bed plate as well?

There doesn't appear to be a shim under the bed plate, but I did not remove it.
I know there are "schools of thought" on weather a bed plate can be removed and put back without adverse effects, I found the horror stories rather convincing, so I chose non intervention in this case !