On 2010-04-07, Jim Wilkins wrote:
On Apr 6, 10:06*pm, "DoN. Nichols" wrote:
On 2010-04-05, Jim Wilkins wrote:
...

* * * * Or -- you could use a sine bar and a cheap set of Chinese gauge
blocks to set the angle of the vise, then once it is clamped firmly,
slide the gauge blocks and the sine bar out from under it. *Typical sine
bars are 5", larger ones 10", but I have one 2.5" one which is nice in a
small machine vise. *(Of course, you have to adjust the size of the
gauge block stack for the length of the bar.) *But the sine bar is a
real winner when you need an angle which would require several angel
blocks to build up the proper angle.
* * * * * * * * DoN.

The 2.5" sine bar sounds like a good idea. The shortest one I have is
3" which is also the width of the bed of the vise and it slips off too
easily.

Take a single parallel and lay it down on the clean bed of the
vise, so your 3" sine bar footprint won't cause problems.

I don't think I've ever had to mill a flat surface at an angle that
wasn't an integral number of degrees, usually a multiple of 5, so the
angle block set has been more useful than my gage blocks. I've used
them with a sine bar only to measure the angle of a conical taper.

I've used the 2.5" sine bar in my shaper's vise to make a piece
of aluminum have half the included angle of an Acme thread to use it in
a toolmaker's vise for setting the half-angle on my surface grinder for
making a couple of Acme threading tools. The toolmaker's vise was
mounted on a sine plate to set the relief angles for the particular
thread pitch being cut -- reversed for the internal threading tool of
course.

The tooth cutter for the tractor steering sector was ground for a 20
degrees pressure angle with a correction for side clearance, but I set
that up in a 3-way-swiveling Univise.

O.K. I don't have one of those.

Enjoy,
DoN.

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