gage blocks

I read Appendix B in the link provided. He makes it clear that wrung blocks are not sticking together because of a vaccum and air pressure:

"What causes wrung gauge blocks to stick together? The earliest conjectures were that sliding blocks
together squeezed the air out, creating a vacuum. This view was shown to be wrong as early as 1912
by Budgett [B1] but still manages to creep into even modern textbooks [B2]."

From his 7 facts about wringing, #4 is were he states the major contributor to adhesion:

"4. The fluid between blocks seems to provide much of the cohesive force. No matter how a
block is cleaned, there will be some small amount of adsorbed water vapor. The normal
wringing procedure, of course, adds minute amounts of grease which allows a more consistent
wringing force. The force exerted by the fluid is of two types. Fluid, trapped in the very small
space between blocks, has internal bonds that resist being pulled apart. The fluid also has a
surface tension that tends to pull blocks together. Both of these forces are large enough to
provide the observed adhesion of gauge blocks."

Thanks,
Bill
 
Aside from all the reasons given, there is something that is more important than why the blocks will wring together. In use there should always be a fine film of oil between the blocks.
After first washing your hands you can use the natural oils on your skin. The inside of your wrist and the back of your neck are good sources.

Gene
 
It has to be more than vacuum/air pressure. When you think about it, air pressure at sea level is only about 15 PSI, compared to full vacuum. To withstand a 200 lb pull (As shown in the Ford text book) on vacuum alone, the surface contact area would have to be over 13 square inches.
 
jgedde said:
My molecular attraction conclusion may well be wrong, despite my results. It seems moisture is adsorbed into steel and cannot easily be removed. Here's an interesting treatise on Gage Blocks by NIST. Appendix B discusses wringing. http://www.neme-s.org/Shaper Books/Gage Block Handbook/Gage Block Handbook.pdf

What's sure without a doubt at this point is that vacuum between the blocks holds them together.

John
Click to expand...



If you see pages 69-70, that's the way we always cleaned the blocks before any inspection, calibration, or set-up.

There is not much else to the safe handling, wringing, and use of Jo Blocks. Some places wore gloves while handling Jo blocks.

Oh yeah, don't throw or drop them on surface plates, or concrete.:whistle::phew::lmao:

Good find there, John.

My opinion is....there is always a film, and suction action; no matter how much care you put into it.
 
I would just simplify things and instead of all the scietific mumbo jumbo, I'd venture to guess that suction is what holds them together because you squeezed all of the air out. :lmao:
 
jgedde said:
My molecular attraction conclusion may well be wrong, despite my results. It seems moisture is adsorbed into steel and cannot easily be removed. Here's an interesting treatise on Gage Blocks by NIST. Appendix B discusses wringing. http://www.neme-s.org/Shaper Books/Gage Block Handbook/Gage Block Handbook.pdf

What's sure without a doubt at this point is that vacuum between the blocks holds them together.

John
Click to expand...

Van Der Walls force (intramolecular attraction) has been known to contribute to such adhesion. It's enough to hold a gecko to glass. The residual solvent surface tension may be more important though.

No, I don't understand the math either.

http://en.wikipedia.org/wiki/Van_der_Waals_force
http://en.wikipedia.org/wiki/Adhesion


Walt
 
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