On 2010-08-21, des bromilow wrote:
Hello DoN. Nichols,

Thanks!!! _ I was pretty sure the string went through the bolt (as opposed
to the nut) but wanted to be sure...

Normally -- you don't want the string all the way through. It
is too likely to fall out the other side. I would probably use a
minimum of three or four times the depth of the threads for larger
bolts, and if there is a lot of load on the bolt, you want it to engage
near the outer side of the nut so you don't weaken the bolt too much.

Why do I want the webpage? - I like to give credit for where I borrow ideas
- simple as that. When I write up this project, I'd like to be able to point
out this little tip and say where I got it from.. right now I can say it
came courtesy of the folks at RCM, but it'd be nice to say where else it
came from.

O.K.

Well ... *I* got it from screws illustrated in the PIC catalog
(they make precision gears and such) and seeing some used in aircraft
style construction (my employer was making flight simulators).

I passed it on in the newsgroup.

Others probably have as well.

But it seems to be semi common practice in certain fields.
(There were also aircraft anti-vibration nuts with a nylon washer
captive in the top of the nut under a rolled lip.)


The machine jacks will be used to set a sine bar because until I have sets
of guage blocks, etc, machine jacks set to a vernier caliper will be better
than nothing.

Hmm ... Chinese gauge block sets are cheap enough. Look at eBay
auction # 180546181693 ($40.00 buy-it-now for a 36-piece set, which
should be sufficient.)

The Chinese sets (which this may or may not be) are supposed to
be accurate within 50 u" (micro-inches -- 0.000050"). I would not use
my good B&S set of "Jo" blocks under sine bars, except perhaps for
precise gauging setups, not for machine setups.

A space block set may do just as well -- depending on how
precise you are trying to be.

At the moment, the search string which has the least clutter on
eBay for this is:

gauge block set* -hoses -manifold -"sight glass"

the last three '-' entires are to keep air conditioning manifolds out of
the search.

If you want a cheaper way to go -- to continue transferring
settings from calipers to the sine bar -- do another eBay search for:

adjustable parallels

Which can be adjusted to various sizes within their range, and at least
will have contact surfaces like a gauge block -- if not as smooth. A
machinist's jack does not have the flat level surface which a sine bar
expects to rest upon.

Look carefully at the photos in auction # 300457608090

You will see that each parallel is split in two along a diagonal
line, (and are held together by a dovetail between the two, not visible
from the plain view but marginally visible by the angled view at the
ends.

Each has a screw (or sometimes two, depending on size) to lock
it as the selected setting.

While these are made for transferring measurements, you still
have a loss of accuracy with every transfer.

And you at least want a micrometer to set them to, not a vernier
caliper if you want accuracy.

Enjoy,
DoN.

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