Re: cam tailstock lock modifications for SB13

m. allan noah

The thread pitch most certainly is relevant. That (along with
clearance, wear and the elasticity of the parts) is what decides what
fraction of a turn is required to lock the tailstock.


On Mon, May 11, 2020 at 11:13 AM wlw19958 <wlw-19958@...> wrote:

Hi There,

Talking about thread pitch (i.e. T.P.I.) is irrelevant. What is a thread anyway?
It is a wedging action arranged in a helix. So, what we're talking about is how
to wedge the tailstock so that it is secure against linear movement when needed.
And un-wedging it when linear movement is desired. So, those who insist that
it has to do with thread pitch are missing the big picture and are concentrating on
extraneous details.

The idea of re-indexing the square head bolt in the tailstock clamp is a viable one.
It provides two more possible combination and it may be enough to work. It will
provide a 30° rotational offset in relation to the flats on the nut (assuming a hex nut).
When I got my first Heavy Ten, the tailstock clamp was a 1/2" block or steel with a
stud in it and hence didn't provide for the re-orientation of the bolt.

Shaving the underside of the nut is of course possible but it make take several tries
to get it where the user wants and once it has been machined down, it is difficult to
put the metal back. I learned a long ago to modify the cheapest part so that if one
screws up, replacement will be cheap. That is why I suggested making some washers.
They are easy to make; they don't require much machining skill (i.e. a beginner can
do it) or tooling. And if it doesn't work, the person is no worst off that before.

Good Luck!
-Blue Chips-
"well, I stand up next to a mountain- and I chop it down with the edge
of my hand"

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