Gauge Blocks

[jason udallParticipant @jasonudall57142]

[jason udallParticipant @jasonudall57142]

[jason udallParticipant @jasonudall57142]

In summary.

Even in the 1920's this was being debated.

The practical " result" was how much does the oilfilm effect size..

From the table above table

Sixteen 1/8" slips were compared to one 2" slip

Parrafin error -0.00001918

Vasleine error -0.00001914

Lubricating oil error -0.00001906

No film.. error -0.00001887

It was noted with no film noticeably less wring was observed..

..

Source npl circa 1922

 

Now it looks like the stack might be low relative to the 2" slip..

And we have a var of 0.00000010…inch..( 1 x10^-7 ) (0.1 micro inch) from oils one to another…

That ought to be good enough for model makers at this scale

Now since the practice was to wring the blocks to the surface plate..we have one layer in the case of two slip and sixteen in the case of the stack… But if the manufacture of the slip includes thickness allowance for the oil film…oh hell who cares!…

The physics of what is the origin of the wring force intrigue s me but it appears to one way or another matter little to use. 

Personally I would get the slip as dry as possible for use and re oil before storage.

Edited By jason udall on 09/01/2015 16:59:10

Edited By jason udall on 09/01/2015 17:05:08

[Larry Coleman 1Participant @larrycoleman1]

Jason

I think we must accept we do not live in a perfect world. Don't forget the atmospheric humidity and as minute as it is it would condense on the surfaces. In the Metrology room the operator wears gloves and at times we donned the mouth mask made of cotton like a brain surgeon to prevent fogging up the surfaces. Now we really were splitting the atom in my opinion.

Now I think that none of us will ever use this type of equipment in model making and I have only seen a gold yard stick once in my life. I wonder if they still exist. It is interesting to wonder if engineering today is still advancing or has our diligence for perfection been lost…

It is exciting to talk to you guys and as a dinosaur of engineering development I have forgotten more than I have learned in the last ten years but I am still learning. I still wonder around the university labs here and build scientific equipment as a volunteer. And some of the Ph.D.'s look at me funny when I say, well lets build a device for that experiment. I built an X ray machine for them but the perils of being able to run it destroyed that unit. Government licenses & WH&S became to expensive.

Take a good look at the three D printer what is it? In fact its a 3D pantograph in reverse. In stead of removing the unwanted material and leaving the target reproduction. We only place the wanted material on the table.

I might start a new thread. Forgotten engineering techniques, Because it is our obligation to pass them on.

Theres a few topics to throw around.

Larry

[mechman48Participant @mechman48]

Posted by Neil Wyatt on 09/01/2015 16:25:41:

> van de Waals force

Eye Level?

 

Van der Valk methinks … after reading this post, & hopefully understanding it, when do I get my degree..

…. ho hum back to back to 'KISS' mod. eng..  I bow to your greater knowledge…

George

Edited By mechman48 on 10/01/2015 10:20:34

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Jerry Wray on 09/01/2015 14:27:32:

Oh No! Not van de Waals forces! There has been much correspondence amongst physicist disputing the existence of these. Perhaps we should all back-off until we have read the latest research papers, Then we might be able to take a view.

For the uninitiated these forces have been in dispute for at least forty years.

Jerry

Well, they certainly existed 50 years ago when I studied physics at university although it has only recently become possible to measure them. Of course the theory has been disputed. That's science. If we accept everything as true we don't progress.

Try telling the geckos that the forces don't exist and they'll all fall off the glass of their vivariums!

Russell.

[Ian S CParticipant @iansc]

When we were setting up our engine/propeller over haul shop back in the 1960's someone mentioned that two surface tables similar to the one with the bent prop on it were wrung together and hung above the entrance of the factory they were made in…. maybe, maybe not.

Ian S C

[HopperParticipant @hopper]

Posted by Russell Eberhardt on 10/01/2015 10:35:29:

Posted by Jerry Wray on 09/01/2015 14:27:32:

Oh No! Not van de Waals forces! There has been much correspondence amongst physicist disputing the existence of these. Perhaps we should all back-off until we have read the latest research papers, Then we might be able to take a view.

For the uninitiated these forces have been in dispute for at least forty years.

Jerry

Well, they certainly existed 50 years ago when I studied physics at university although it has only recently become possible to measure them. Of course the theory has been disputed. That's science. If we accept everything as true we don't progress.

Try telling the geckos that the forces don't exist and they'll all fall off the glass of their vivariums!

Russell.

And off the walls and ceilings of my workshop here in the tropincs, including the motion detectors of my newly installed burglar alarm with rather annoying results!

[Larry Coleman 1Participant @larrycoleman1]

I think we all may be missing the point here, Forget the oil, Has anyone thought we may have improved the way a surface finish is accomplished as well as the end result.

Now I do know if you want to remove oil of a surface Ultrasonic Vapour degreaser is the way using freon 13. The military eccept it. And a vapour degreaser cleans in pure fluid because it is condensed by the cooling ring.

Anyway a very interesting conversation.

Larry

[Neil LickfoldParticipant @neillickfold44316]

Jason interesting post.

So I just got 15 blocks and cleaned them as I normally do, then assembled them. My mic reads to .001mm,

Then I redid the test again, and this time put a thin film of non scented baby oil on them. I got the same measurement.

I really was expecting a measurable error of at least 4 to 5 um. I put together 1.01 to 1.6 and got 17.555mm should have been 17.550, but with the error of the blocks added up that makes it about right. I think baby oil is parafin oil as it just calls it light mineral oil.

Neil L

[jason udallParticipant @jasonudall57142]

My point really is..we are not alone in considering the impact. .it seems to have been an issue in at least 1922..

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 01/11/2014 15:02:05:

… Careful reading of Appendix B in the NIST document [referenced above] should clarify the matter.

… it's only a couple of pages; unless you follow all the references

.

Quite so, Jason

MichaelG.

.

For those who didn't read it, here is the reference again.

[jason udallParticipant @jasonudall57142]

Michael…facinating..in particular the assessment of contact area from resistivity. ..
Particularly liked the noted reduction in wring as the slip “wears” or possibly “polishes”. …

[Michael GilliganParticipant @michaelgilligan61133]

Just a quick PostScript

[we don't really want to resume the debate, do we]

Have a look at this, from NPL.

MichaelG.

[Neil WyattModerator @neilwyatt]

It's very telling that the NPL talk of 'achieving an uncertainty' rather than 'achieving an accuracy'.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 21/02/2015 16:21:46:

It's very telling that the NPL talk of 'achieving an uncertainty' rather than 'achieving an accuracy'.

.

It's much better use of English, I would say.

MichaelG.

.

Edit: This is a good place to start.

Edited By Michael Gilligan on 21/02/2015 17:07:33

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