Myford S7 Spindle Nose / Chuck fitting.

I suggest that just because a thread isn't meant to be used to ensure the fit doesn't mean to say that on millions of lathes made some won't turn out to work ok on the thread.

After all if the register and thread were cut at the same time wouldn't the flanks and other dimensions of the thread end up just as concentiric and in effect are a taper that mostly would inadvertently result in alignment unless thrown out by some crud. with age of course the thin bits of the threads could wear unevenly and degrade the fit but it isn't per se a deliberate misalignment.

What about the literally 1,000's of lathes that were mde with no register, early Myford, drummond, Winfiled, pooles, gamages etc.??

A chuck etc, can only be restrained radially (by design) by either the thread or the cylindrical part of the register, but not both at the same time or interchangably - it's got to be one or the other. Lathes made without registers were just designed that way and weren't intended for really accurate work, why else would any manufacturer bother with registers? Martin.

Of course a threaded only spindle will and does work but I would imagine was only chosen for cheapness. We then move up to parallel register/thread and then the most expensive but prefered option is tapered register and either a screw or cam locking system, I'm sure if a thread only spindle was acceptable the large machine manufacturers would not spend a fortune making the fancy tapered location varieties?

Tony

Blowlamp, just read your post. Another principle I picked up along the way is that you do not need two registers to do the same thing and is incorrect and adds extra cost .

Tony

I think you are forgetting that the large machine manufacturers sometimes need reverse, although the Harrison L5 and the early Colchester master had screw on / fly off spindles.

I think that's called a 'redundant constraint'. Martin.

Ok so will will do away with the register like the early machines..

We know this works.

Now we will do away with the thread and just keep the register. OOps - clunk

So this proves emphatically we need the thread but not necessarily the register ?

John S.

Edited By Chris Trice on 27/12/2012 16:22:09

It must be Christmas! I can see angels dancing on the lathe spindle nose - now haow many are there?

> Now we will do away with the thread and just keep the register. OOps - clunk

Unless you have a camlock or stud fixing... and are inherently superior IMHO

Neil

Seen a thread on another forum where there was a problem with a camlock that was bottoming out on the flat rear face (not sure what to call that) before the taper had made full contact. A problem of poor manufacturing tolerance of course which is where this thread started.