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  • Work in metric????

    I would like to know how many other readers of Home Shop Machinist prefer to work in metric units????

    Jon Kutz Minnesota USA
    Jon Kutz Minnesota USA

  • #2
    I do prefer to work in metric. It is much easier to do design work in metric once you get the hang of it. Also, the math involved in doing the machining is easier with one less decimal place.



    • #3
      To be fair we should also ask those who feel the other way on the subject to post in that thread

      I think I will have to come down on the side of inches.

      I work in both systems as the jobs present themselves and on the mill with its DRO it is not much of a problem as I can just flip the switch... modern electronic measuring gear also helps when a metric job is required.

      The bar and flat stock I hold is 98% imperial and things like drills and other tooling is cheaper and more available than metric for me.

      The sources of scrap for the scrap box are almost all imperial in sizing so that when a project from the scrap box is knocked out it will also be inch based.
      BUT the fact remains that the vast majority of Home shops in the is country (and hence the readership of HSM) have older equipment that has bee sourced from the used market...

      In my shop all of my heavy tools were built between 1940 and 1960 and I think I am more the norm than the exception in this.

      Lathe work is for me the area that is the most work when working a metric project and as a result of a few bits of scrap produced in the past I now convert all metric projects to imperial measurement before I start if they involve lathe work.

      Despite working in the metric system since my days at school I still do not visualize things that are quoted in metric measurements.. and this visual component is an important check in the 'rightness' of a process... is what I ma doing making sense in relation to the Print I am working from... with metric the extra mental step must be taken to convert before the check for 'rightness' is accepted by my brain.

      A case can be made for a model made of a prototype that has been built in metric to be modeled in metric but the vast majority of things that are modeled by an HSM (or are made for antique restoration) are inch based. even some of the modern firearms I have worked on from Europe have had imperial threaded fastenings

      As most of our (the readership of HSM) shops are imperial based it makes much more sense for the shop tools and accessories that we build for it from the pages of HSM should also be imperial based. When I made the transfer block from MLA it would have made little sense to build it to an even metric size rather than an even imperial size...

      As the metric readers of HSM are such a small minority of the readership I think that the onus is on you to translate any projects that you build to metric if that is needed.

      The case for MEW is somewhat different as it is an European publication where it is cheaper and much easier to obtain tools and stock in metric sizes than in imperial for use it is the reverse

      Randolph Lee


      • #4

        Most of my shop equipment was built in the first half of the twentieth century and is not particularly metric-friendly. Additionally, it seems that the bulk of the raw materials purchased or scrounged today in this country are in imperial dimensions. Perhaps the continued use by the automobile industry of metric fasteners will serve to enhance the available supply of metric materials.

        Randy certainly has a valid point about the ease of use of either system when electronic equipment is available. Maybe a simple project or two in HSM using the metric system would generate a few converts from among us infidels.

        Frankly, however, the path of least resistance seems to be continuing to work with imperial measurements and thus continuing to wallow in our recalcitrance.

        Jim Heekin
        Orlando, Florida


        • #5
          Here we are agian..fancy meeting you in place like this!!!!
          I had using the metric system(we discussed this before)and will only use it if there is no other way.
          I not in favor of using the metric system.


          • #6
            <font face="Verdana, Arial" size="2">Originally posted by Jon Kutz:
            I would like to know how many other readers of Home Shop Machinist prefer to work in metric units????

            I like the metric measuring system. I wish the USA would make the decision to change and be done with it. Back in the mid-1970's there was a push here in the USA to go metric, but that didn't happen because I think of the typical stubborn nature of American workers. In 1985 I worked in a non-union shop that supplied rocker arms to all the US car and truck manufacturers, the shop being in NJ, & not AFL/CIO. We worked all metric dimensions and the machines were US inches and not CNC. We were always converting and it was a pain.
            In my home shop I keep a metic meter stick handy and use it when ever I need to divide something into multiple units, being that it is much easier. And I keep my conversion charts handy as needed.



            • #7
              Of course the metric system is better, the whole world (almost) is using it exept the USA.


              • #8
                Fractional, numbered, and A-Z drills have been replaced by decimal Metric (i.e. 17.3mm) everywhere but England, the USA, and parts of Canada. Once you start using the metric system it is much easier than the old system we now use. Converting an old iron beauty to Metric would at most require new dials and/or lead screws. At any rate, knowing the two systems will benefit you more and add to your expertise.


                • #9
                  I do all my calculations in Metric, and would hate to have to do it any other way.
                  The moment of inertia of a metric section is a breeze...
                  Alas, I was still raised in inches and feet and have an imperial leadscrew. All my bolts, nuts, taps and dies are imperial too.
                  Metric drills are great for drilling tapping size holes though.


                  • #10


                    • #11
                      Heck, all said and done, if you know your conversions, and own a calculator, this is no issue. If you own met tools such as a mic, caliper, and mag indicator, you can do this well.

                      In CNC Programming, if the project is metric, I program metric. It is just a G70 (G20 for some machines)inch programming mode switch, or G71 (G21) switch in the start of the program.

                      Here is one for you CNC Lathe guys. I got a program to make, all imperial dimensions but for a met thread. Tried this out on a piece of scrap stock first. Programmed the entire part in english but for the thread, then used the "inch / Metric" G-code switch for the thread, then switched back to english afterwards.

                      I have done this with Met tapping as well on a mill.

                      Anyone else a CNC person whom has done this?
                      CCBW, MAH


                      • #12
                        Good Idea. Give your students a project with half Imperial and half metric measurements and tell them you expect it to work perfectly. A hot air engine is good! I am evil.


                        • #13
                          My machines are all imperial but I do a lot of my work in metric. Why? My micrometers above 1 inch are metric. I have a set of 3 snap gauges in metric, range 0 to 25 mm, accuracy .00004 inches, that I paid 30 dollars for. They retail at $1200 each. I have a dial indicator, same accuracy, $5. Now you know a good reason to consider metric. This stuff was all government surplus with recent calibration stickers.


                          • #14
                            A metric gage with 0.00004 INCH accuracy? What's wrong with this picture?
                            Jim H.


                            • #15
                              What's wrong is: one too many decimal places.
                              More like 0.0004! Sorry about that.