Myford S7 Spindle Nose / Chuck fitting.

[Chris TriceParticipant @christrice43267]

Any crud in the thread probably does throw off cocentricity quite a bit. The register is their to limit its effects but then crud on a taper mount does the same thing.

[blowlampParticipant @blowlamp]

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.

[Tony Pratt 1Participant @tonypratt1]

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

[Tony Pratt 1Participant @tonypratt1]

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

[John Stevenson 1Participant @johnstevenson1]

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.

[blowlampParticipant @blowlamp]

Posted by Tony Pratt 1 on 27/12/2012 15:28:00:

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

[John Stevenson 1Participant @johnstevenson1]

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.

[Chris TriceParticipant @christrice43267]

Tony, a thread is all that’s needed but the register is there as an additional safeguard to limit eccentricity. It can only centralise a chuck to the limits of the clearance between register and backplate. If modellers could be trusted to keep the threads of both chuck and spindle spotlessly clean, the chuck would always find the same fitted position each time in the same way that a centre and centre drilled hole will without the need for a register. Only a spindle with a taper mount, also kept spotlessly clean will automatically and actively centralise a chuck to its exact concentric position. Any tube containing a shaft can only hold the shaft within the boundaries of its bore to the limits of the clearance between them.

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

[Sub MandrelParticipant @submandrel]

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

[BazyleParticipant @bazyle]

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.

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