On Wed, 28 Jan 2004 08:06:15 -0500, BRuce BRuce wrote:

I confused, wouldn't the helix angle be the same regardless of the
diameter? threads per inch is threads per inch. the angle doesn't
change but the surface area changes.


the angle decreases as diameter increases.

think of one rotation as a triangle. height is thread pitch- it stays
the same. width is diameter- it changes, so the diagonal must change
too.





Yes, I will have to run a lot of turns when changing from one operation
to another but if I am clamping a board to plane, a single turn release
or to reclamp the board is all that will be needed. most metal bench
vices have fairly high TPH and some do have quick release.

Once my bench has been finished I will post pictures and number of turns
full open to full closed.

BRuce

Andy Dingley wrote:
On Mon, 26 Jan 2004 21:58:48 -0500, BRuce BRuce wrote:


I plan to use 2 - 1 1/2" for a tail vice, you are looking to hold the
wood not squeeze it into submission.


It's a question of helix angle. You need at least a certain pitch on
a vice, or else you'll be winding it in and out all day. If you cut
this onto too small a diameter, the angle of the thread is too steep
and it doesn't hold.