French precision machining vice - swivel base puzzle

[bambuko]

I have inherited an excellent French precision vice.
It comes with a swivel base, but normally I use the vice mounted directly to the table (without swivel base).

This is my vice seen from below with the swivel base.
Trouble is that when I tighten the three bolts (arrowed) securing base taper, it locks things solid.
I thought that one should be able to swivel the vice until the two bolts on the side of the base lock it?
Does this mean that the base is only pre-setable with vice off the table and cannot be swiveled after the base is secured to the table?
or... am I missing something?

 

[pressbrake1]

Nothing to add about stripping it down but..
If you have the height to keep the swivel base it allows very accurate clocking in

 

[Agroshield]

Shim between base and main vice body using cigarette paper, aluminium foil etc. until desired degree of friction on taper is achieved.

 

[bambuko]

Nothing to add about stripping it down but..
If you have the height to keep the swivel base it allows very accurate clocking in

no problem with height
I love this vice - very precise indeed and great for small jobs

Shim between base and main vice body using cigarette paper, aluminium foil etc. until desired degree of friction on taper is achieved.

yes,
shimming it, works
I am just surprised that in such a precision piece of kit (you can easily pay £2500 for a new one) one has to resort to shims

Thank you guys,

 

[Agroshield]

I am just surprised that in such a precision piece of kit one has to resort to shims

The gib strips on a Moore jig borer are just adjustable shims.

It is possible that the first person ever to remove the swivel base lost the factory shims.

Cheaper to shim it than to fit (as in employ a person called a fitter) two parts together that have gone along two different production lines and only meet at final assembly.

Consider how it would be fitted: check, grind a bit off, check again, grind some more off, now too tight, throw base in scrap bin and go back to step one.

The opposite, when you tighten the capscrews until they snap and then back off 1/4 turn and still it rattles around like a sausage in a sock, is a lot harder for you to fix.

If you were keen you could drill and tap the base for three grub screws (jacking screws) that act in the opposite direction to the base securing screws. That is how you set the clearance on a Vertex rotary table.

 

[bambuko]

It is possible that the first person ever to remove the swivel base lost the factory shims...

more than likely...
I have never seen any shims, and I guess it was used in the toolroom without anyone ever swiveling the vice?

​

....If you were keen you could drill and tap the base for three grub screws (jacking screws) that act in the opposite direction to the base securing screws.

not that keen
that thing is properly hard

Interestingly, later models of the same vice have different swiveling base: