Talk:Surface plate

Shortages

The section about the use of glass seems to have some grammar problems, but I just want to check that I understand before editing. "when material and production dead lines were either in short supply or over stretched."? is this just a clumsy sentence or does "dead lines" have a special meaning here? Theoh 21:36, 17 January 2007 (UTC)

"Deadlines" is what the person meant. - Toastydeath 05:13, 18 January 2007 (UTC)

OK, fine, I have replaced that sentence with something less convoluted. Theoh 15:20, 18 January 2007 (UTC)

Misinformation - needs correcting - please review CURRENT journal publications

I have the book - it was written in 1970 - some things are now known that contradict this source. User 'I already forgot' doesn't say what is claimed below. It is true that granite has a different coefficient of expansion than steel - but makers of ultra precision air bearing lathes - use granite - not iron or steel.

The book actually lists a table with advantages and disadvantages - the claim that it says "long-term stability of properly poured cast iron is superior to the dimensional stability of granite and ceramics" is false - it does say "Experiments by Meyerson and Sola* make clear that there remains much to be learned about dimensional stability."

The source should at least specify the page number...

And much has been learned after 1970.. Moore pushed the limits of the time - but time marches on.

This link has a section on stability - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4654600/

Gauge blocks are not made of iron - they are made of specially treated steel - that has been cycled in LN2 - to achieve long term stability. Other materials appear to be similarly stable.

That being said - cast iron that is properly poured - aged - heat treated to remove stress. is quite stable - - but not as stable as granite - at least if it hasn't be cycled in LN2 - and iron surface plates don't/didn't get such a treatment. but not used as a standard because interferometry is MUCH more accurate. Granite that is kept dry is also quite stable. Today, Mitotoyo makes gauge blocks out of ceramics.. Things have changed from 1970..

Also see - http://starrett-webber.com/GB68.html

Also of note - iron surfaces used to scrape machines are often hung and wrung - - and change shape. The same does not happen to granite. If you drop the iron - it has to be re-calibrated - using a granite surface plate. The iron is used for it's ability to hold ink and because it isn't as heavy as granite.

Moore is a tool company - a really good one - but look at newer research and practice

Wayne R. Moore, in Foundations of Mechanical Accuracy, details how the measured and verified long-term stability of properly poured cast iron is superior to the dimensional stability of granite and ceramics. Granite surface plates are fine for machines with lower accuracy requirements such as a CMM, but passing into millionths of an inch and beyond, cast iron is one of the few choices available for static, long term gage stability. Cast iron masters are used to produce laboratory-grade granite surface plates. The book was written in 1970; it is still in publication, and this section has not been revised by the Moore Special Tool Company. However, the age of the book has nothing to do with cast iron being a far more metrologically stable and suitable material for the extremes of accuracy.

I don't know how to link the citation I inserted to the section that needs it; my apologies. If someone would add it, I would be grateful. - Toastydeath 18:41, 26 July 2007 (UTC)

Lower accuracy measurement? Uh, I have to disagree with your recent addition to the article where I put the fact tag but my real world experience in high accuracy environments would be considered OR so I'll have to follow the rules and give in to your ref'ed material. --I already forgot 23:13, 26 July 2007 (UTC)

For the sake of clarity, I said "lower accuracy" as Moore Special Tool builds machines that have surfaces flat and parallel to a couple millionths of an inch over the entire machine envelope without any electronic compensation, and the machines still hold that accuracy today (arguably greater accuracy now than when the machines were first made, as they did not have the means to resolve the machine's full accuracy back in the 70's). The digital compensation maps that modern CMMs use to allow them to measure in the same realm that Moore was doing by purely mechanical means back in the 70's still have to be updated and re-certified as the granite shifts if the machine is to be used at its limit of accuracy. That being said, cast iron has a far greater thermal expansion coefficient and as the current article says, burrs, and is not useful in a laboratory environment not set up to create and handle master gages. In 98.5% of laboratory settings, a cast iron surface master is more detrimental to accuracy than a granite surface plate. I just wanted to add into the article that cast iron masters are still used, and where. - Toastydeath 05:24, 27 July 2007 (UTC)

Without addressing other issues, I added the fact tag to the statement that "cast iron remains most popular material for surface plates among machine builders, gage makers, and other high-accuracy industries". Having worked in the "high-accuracy industry", I personally know that the statement has a great potential to be false as I have never seen a cast iron surface plate used outside of being a lapping device to create more precise surfaces. If you have ever inspected and created objects to a .0001 of an inch or better, you now that thermal expansion and magnetism is a major concern during the inspection process and that cast iron could never be used for such inspection. Ever grind a semi-conductor die plate with gas channels that was held to .0001 or better that was .120 thick? That and numerous other high precision parts and gages could never be inspected on a cast iron surface plate because of the error created by the magnetism alone. The thermal expansion of a hand resting on a cast iron plate and oxidation would be enough to turn QC manager away from using cast iron for high precision parts so I find it interesting that the statement about cast iron remaining the most popular material would be added to the article as fact. I'm not saying it isn't fact, but its very suspect. --I already forgot 06:47, 27 July 2007 (UTC)

I can understand the skepticism, but without copying the first quarter of the book, I don't think I will be be able to convince you otherwise. I do recommend the book if you have interest, as it is still an industry reference. Perhaps you will still disagree. My personal experience has been doubts as to such claims in the beginning based on what I knew, but between actually getting the chance to read the book (it is difficult to find) and having the opportunity to speak with Jim Bryan, a pioneer in diamond turning and the gentleman who holds the patent on the telescoping ball bar, I became convinced that these principles are correct.

I do know that temperature is a huge concern. The book not only details temperature control and destratification, but also goes into the effects of gravity, sag, atmospheric pressure, indicator deflection, and others. It also details the control and correction of those factors as well. A granite surface master is not used as a surface plate - you do not inspect things on a surface master as you would a normal surface plate, and I am not suggesting anyone would ever want to use something that has the thermal expansion coefficient of cast iron for such tasks. The purpose of a cast iron master is to provide a flat surface; a surface, when flat, will be flat at 20 C and flat at 30 C, though dimensionally larger at 30 C than at 20 C. From this stable, accurate surface, you can then transfer the flatness or parallelism from the cast iron surface to the granite surface, for use in laboratory equipment. The cast iron plate can be used as an inspection surface, but this requires special training and consideration on the part of the inspector. When working down in the ten millionths and under range, any local heat change at all is going to invalidate your reading, no matter what material it has been made from.

I am not suggesting that cast iron is a superior material for inspection and I apologize if it sounded that way; trying to inspect a tolerance of .0001" or .00001" is well suited to a granite surface, and the disadvantages of working with a cast iron plate would completely outweigh the benefits. Cast iron surface plates are used as master references for flatness; I will change the article to better reflect that. - Toastydeath 10:07, 27 July 2007 (UTC)

"...without copying the first quarter of the book, I don't think I will be be able to convince you otherwise." Well, that sounds like WP:OR used to advance a position. The new change (the use of masters/standards) and a few other statements opens up a new can of worms but so it goes. --I already forgot 22:20, 27 July 2007 (UTC)

History?

I would like to fill in some of the history of surface plate construction, but I cannot find the source that I once had. I think it was a book (or perhaps it was just the head of workshop) at the ANU wood workshop, that stated that it was Whitworth who invented the procedure of AB-BC-CA tri-plate flattening (i.e. taking three plates A B & C and wearing them against each other to reach equilibrium). Does anyone know if this is true? Or where one might find more information? Or just any general history of the development of surface plates in the 19th century? Thanks! — Sam Wilson ( Talk • Contribs ) … 00:48, 7 March 2010 (UTC)

Yeah, see Flatness (manufacturing). Wizard191 (talk) 00:52, 7 March 2010 (UTC)

Thank you. I've amended the link in the first paragraph. — Sam Wilson ( Talk • Contribs ) … 00:57, 7 March 2010 (UTC)

see... The Whitworth Measuring Machine 1877 "A remarkable advance in the direction to which we have referred was made prior to the year 1840 by Sir Joseph Whit- worth, and formed the subject-matter of a paper read before the meeting of the British Association at Glasgow in that year. Specimens of truly plane metallic surfaces were then, for the first time, brought under the notice of scientific men, and the method of preparing such surfaces was also made known. Up to that time the process relied upon for obtain ing plane surfaces on metal plates, and indeed the only one practically used, had involved the operation of grinding two plates together with emery powder and water."

and... Minutes of Proceedings of the Institution of Civil Engineers, Volume 91 "In 1825 he married Fanny, youngest daughter of Mr. Richard Ankers, and shortly afterwards came to London, to the workshop of Messrs. Maudslay. He soon won a position as one of the best workmen, and while here he made his first great discovery, which consisted in the mode of construction of a set of perfect plane surfaces. Up to that time the most accurate planes had been obtained by first planing and then grinding the surfaces. They were never true, and young Whitworth became possessed with the idea of making a true plane. At the next bench sat a Yorkshireman named John Hampson, a good workman and a good fellow, who took an interest in his young companion’s work. One day as they worked Whitworth ventured on an idea. 'If these planes were true, one of them ought to lift the other.' 'Tha knows nowt about it,' was the cynical reply of steady-going experience. Whitworth kept on at his problem, working quietly at his lodgings. His first step was to abandon grinding for scraping. 'Taking two surfaces,' he said, when telling the story afterwards, 'as accurate as the planing tool could make them, I coated one of them with colouring matter and then rubbed the other over it. Had the two surfaces been true, the colouring matter would have spread itself uniformly over the upper one. It never did so, but appeared in spots and patches. These marked the eminences, which I removed with a scraping tool until the two surfaces gradually became more coincident'

But while his skill as a workman was thus being made the most of, Whitworth‘s mind was not idle. He saw that his first thought was not enough. Two surfaces might lift each other by fitting perfectly and yet not be true planes. One might be convex and the other concave. A new light came. Make three surfaces. If each will lift either of the others they must be planes and must be true. After another stage of skilful labour the three planes were made and the test fulfilled. The Sunday after the problem was solved Whitworth called on his old mate. 'John,' said the young man, 'come to my house ; I’ve something to show you.' The true planes were exhibited. 'Ay! tha’s done it,' said John. That was probably the greatest moment in a great life. Joseph Whitworth had perceived that a true plane was the first thing needed for the improvement of mechanical construction. He set to work to produce it, and by sheer clear thinking and honest work he did produce it." ...........................................................................

and... Tools for the Job by L.T.C. Rolt "..according to some writers it was Whitworth and not Maudslay himself who first demonstrated the art of finishing a surface plate with a hand scraper."

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Maudslay knew the importance of a true surface plate but had not succeeded in making them with the lapping process, it was Whitworth who added the idea of scraping rather than lapping and succeed. There are many references available that show that Whitworth invented the scraping of true surface plates, just google it.=Motorhead (talk) 16:05, 8 October 2015 (UTC)

Antenna connector socket surface plate

Is this type included in the article?: Socket surface plate . --Diamondland (talk) 13:02, 10 November 2010 (UTC)

This article is about the metalworking and inspection tool, not a finishing piece for an outlet, so no it shouldn't be included. Wizard191 (talk) 14:03, 10 November 2010 (UTC)

'Making of a surface plate' copyediting

This section has now been copyedited to the best of my ability but I know nothing about this subject - I suggest someone who does insert the correct citations ASAP. --Eralam (talk) 21:16, 8 October 2017 (UTC)

Image is confusing

The image file seems to show a surface plate with an embossed pattern on it. Certainly that is a leather protective covering or something? 80.229.146.237 (talk) 20:29, 2 November 2017 (UTC)

It looks like it... unfortunately the person who took the image is likely Polish... — Preceding unsigned comment added by I5-X600K (talk • contribs) 02:11, 2 December 2020 (UTC)