I think you are a bit picky. That is what I was talking about.
The ionic isn't just liquids. If you have a molecule of Iron and in
the mix is anything else (as in always) some part will be attached to Fe
and the other part hanging out for something to bond to. Think of Carbon
it can have Hydrogen attached or sulfur..... so a non-balanced molecule would
be making an ionic bond to fill the requirements.

Any part has error in the edge. The bar that is used to touch the sides
has lots of errors in the 'so called' round bar. Might be an oval, a D or

The flat of the 'chair' all sides have tolerances. Mixed with the 'bar' and
this becomes a rich set of offsets. Mixed with a tilt of any kind or reason
and it becomes richer in offsets with one or more angles causing a touch point
to be different down the edge.

In general the fast helpers are used when tolerance is tight. If you are
making something for a shovel, than it wouldn't really matter.

Martin

Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
TSRA, Endowed; NRA LOH & Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Charter Founder
IHMSA and NRA Metallic Silhouette maker & member.
http://lufkinced.com/


BottleBob wrote:


Martin H. Eastburn wrote:

Precision measurements - maybe outside your area - are made with
blocks.

Martin:

I think the term you're looking for is gage blocks, or Jo blocks
(short for Johansson blocks). As far as "...maybe outside my area"; I
probably have at least a passing familiarity in the use of Jo blocks as
I've been wringing stacks of them together since my Tool & Die
apprenticeship days in the early 70's. Currently, as an employee I
have, and use, my own set of round Jo blocks plus use the shop's square
set on a regular basis.


The blocks are often in two or three materials and all hold
by ionic or molecular forces.

An example of an ionic bond is sodium chloride.

The wringing, and adhesion of, Jo blocks is a phenomenon that has a
number of possible hypotheses. Covalent bonding, metallic bonding, van
der Waals force, Casimir effect, the expulsion of air between the
surfaces and resulting 14 psi holding force, surface tension of water or
oil, or a combination of any of the above or other factors not listed.


So if there is a little coolant or sliver under an edge and a bur
is within the corner relief - the coolant will hold off the edge
providing
some level of error. Then there are inherent errors on all edges
including
the touching edge of the finder.

I'm not sure what the relevance of wringing Jo blocks is to putting
a "chair" indicating device on the side of a part. But I'll certainly
concede that burrs, slivers, and debris could throw off accuracy if they
weren't cleaned off first.
As I stated elsewhere in this thread, I don't often use the "chair"
device due to it's, IMO, greater chance of introducing possible error.
Often from tapered part edges.




----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.pronews.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= - Total Privacy via Encryption =---