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Old School Accuracy?

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  • #16
    Pete.

    The word I was trying to remember all day is "NIST":

    http://en.wikipedia.org/wiki/NIST


    Google report on NIST:

    http://www.google.com.au/#hl=en&rlz=...w=1920&bih=785


    Starret calibration service (NIST traceable):

    http://www.starrett.com/metrology/me...ation-services

    Any NIST laboratory wil let you know of any in your area (Universities included).

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    • #17
      Pete was kind enough to send me a set of scans relating to the DTI (a diagram and a couple of accompanying pages). I put them together in a single PDF here:
      www.digitaldownpour.com/OldSchoolDTI/OldSchoolDTI.pdf

      Since the PDF lost a little bit of clarity during conversion, I also put up JPGs of the scans Pete sent, that have just had the empty space cropped out, and had the shadows cleaned up a little bit - they are available here:
      http://www.digitaldownpour.com/OldSchoolDTI/dti_1.jpg
      http://www.digitaldownpour.com/OldSchoolDTI/dti_2.jpg
      http://www.digitaldownpour.com/OldSchoolDTI/dti_3.jpg
      Max
      http://joyofprecision.com/

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      • #18
        Many thanks Max,
        Those look even better than my scans first did. That should work well for anyone interested.

        Pete

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        • #19
          Originally posted by mars-red
          Pete was kind enough to send me a set of scans relating to the DTI (a diagram and a couple of accompanying pages). I put them together in a single PDF here:
          Those are out of a Lindsay Publications reprint book. "Accurate Tool Work" is probably the name, I have a copy around here somewhere.

          It's a reasonably useful book. not wonderful, not worthless.
          CNC machines only go through the motions

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          • #20
            One must always bear in mind the distinction between accuracy and precision.

            Precision is how much detail the story contains.

            Accuracy is how true those details are.

            In most cases precision is more important than accuracy. That is because what is usually needed is repeatability. If you are making more than one of something you only need accuracy once, after that you need precision (repeatability).

            If you are only making one of something then all you need most of the time is precision unless you must make something to fit an item that you aren't making. A good example of the latter is threading to fit a premade thread. Then accuracy is required as well as precision.

            Also, repeatability is cheap, accuracy is expensive. If I need to make 10 somethings X distance long on my lathe I can easily do it to much less than .001 deviation between pieces. It is making the first item to be as close to X as required by tolerances than can be difficult.
            Free software for calculating bolt circles and similar: Click Here

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            • #21
              J Tiers,
              I didn't know Lindsay had reprinted that one. I took the scans out of a 1923 Edition of the book. Yeah there is a lot that isn't written towards the HSM. Still, It's pretty interesting just what they were capable of back then.

              And Evan is of course 100% right. Getting the first one correct is the tough and time consumeing part.

              Pete

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              • #22
                Wilhelm Huxhold's exquisite pair of triple expansion steam engines complete with duplex steam pump;



                There aren't many who can measure up to his level of craftsmanship.
                Jim H.

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                • #23
                  Jim,
                  Now those are true works of art. You wouldn't know if he worked off of someone elses drawings, Or did his own would you?

                  I'd very much like to find a set of drawings for one of those engines.

                  Pete

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                  • #24
                    Very very nice work indeed.

                    Some - many - modellers are really good and take what ever time is needed and they are very good at working out their work schedule as well.

                    No rush, tear and bust there. Some take many months or years to get there too.

                    Most will have small machines and use HSS almost exclusivley.

                    A lot different to some here who seem pre-occupied with tear-ar$ing and pseudo "production" mode.

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                    • #25
                      I would not romanticise the "old time craftsmen" too much as the examples usually shown are usually from a very small minority whose working conditions seemed to be good whereas many were on actual/almost subsistence wages level wages - when they had work - was at best "deplorable" in many cases. Some were all but illiterate as regards math and reading and writing (English). Some - as is still the case in the wider community today - were functionally illiterate.

                      It was these conditions that gave rise to the Unionisation in the work-places and some of the worst of employer/union/employee disputes took place in some terrible places with terrible outcomes.

                      http://en.wikipedia.org/wiki/Trade_union
                      Last edited by oldtiffie; 03-12-2012, 03:55 AM.

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                      • #26
                        What 'Tiffie says is true about conditions.

                        I'd not minimise the skill of even (or especially) the workers in the bad conditions... they produced good work in rotten situations in many cases. people of a certain type tend to do good work regardless.

                        And of course some others showed up drunk and left nearly sober, to get drunk again as soon as possible......work output likely to match.

                        And, you know what? Both those types still exist..... at work everyday
                        CNC machines only go through the motions

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                        • #27
                          uncle pete, I don't know what plans Bill used for his engines. It says that he scaled down a set, but not where he obtained them. Whatever plans he used, note that they are for a complete powerhouse and engines and condensing equipment are duplicated in right and left hand versions, including return pumps and are functional.

                          There is more information and more of Bill's work here;

                          http://www.craftsmanshipmuseum.com/huxhold.htm

                          I find some of Tiffies remarks regarding the craftsman of the times rather dismissive. We are talking late 1800's and early 1900's. Working conditions were not the best when compared to today's standards, but they were what they were. The trade was considered honorable and you will see in most illustrations and photos, the craftsmen of the day arrived to work and worked in coat and tie.
                          Jim H.

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                          • #28
                            Funny, those indicator drawings look exactly like the Gladwin indicators I use all the time. My favorite indicators. Compact and easy to set up.

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                            • #29
                              Originally posted by JCHannum
                              Wilhelm Huxhold's exquisite pair of triple expansion steam engines complete with duplex steam pump;

                              There aren't many who can measure up to his level of craftsmanship.
                              all the more so when you realize they could pretty much fit in the palm of your hand...and despite their diminutive size, the detail is exquisite
                              in Toronto Ontario - where are you?

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                              • #30
                                JCHannum,
                                Many thanks for the information. I very much appreciate it.

                                For anyone who would think poorly of these tradesmen and engineers? You should do a bit of reading about just what they acomplished in what most would think of as a very short time period. Acurate ship board clocks for navigation purposes built to extreme levels of accuracy, Incredibly complex steam engines, Standardised threads and many other standards used today. The invention of gage blocks accurate to within millionths in the eary 1920's, The massive manufacturing required during the second world war. And all of this done with skill and determination. Considering just how far we have come since the start of the steam age to where we are today? That is a very short time period compared to all of human history.

                                Pete

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