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Shop made parallels for the mill?

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  • Shop made parallels for the mill?

    This idea is probably 150+ years old!

    I made a couple of 'parallels' for my mill, I clamped scrap steel blocks to the mill table and took a light cut over the top surface with a fly cutter.

    I had previously stamped the letter 'L' on the end of each one to remind myself to always use them aligned the same way on the mill table.

    According to my tiny brain these should be as 'perfect' as I will ever need.

  • #2
    I have some of those too - and a set of "inaccurate slip gauges" for not-so-critical setups, ranging between 0.050" and 6" cut from a length of 20x20mm cold-rolled and milled then lapped to size - good enough for most of my uses at <1 thou" tolerance! For small adjustments I add a few pieces of shim or feeler gauge to the stack, then measure and repeat...

    Dave H. (the other one)
    Rules are for the obedience of fools, and the guidance of wise men.

    Holbrook Model C Number 13 lathe, Testa 2U universal mill, bikes and tools

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    • #3
      I think this is only true if you always use them in the same spot on your table and clamp them in exactly the same manner they were clamped when you machined them.

      Phil

      Originally posted by The Artful Bodger
      According to my tiny brain these should be as 'perfect' as I will ever need.

      Comment


      • #4
        Originally posted by philbur
        I think this is only true if you always use them in the same spot on your table and clamp them in exactly the same manner they were clamped when you machined them.

        Phil

        You could well be right and that kind of calls into question the worth of factory made parallels too which would only be accurate in some places and not others?

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        • #5
          Originally posted by The Artful Bodger
          You could well be right and that kind of calls into question the worth of factory made parallels too which would only be accurate in some places and not others?
          I respectfully disagree.
          Factory parallels are parallel to within the tolerance specified.

          Parallels made on your mill simply match the angle at which they were milled.
          These fall into the category of measurement tools, most of us have to buy them just like we buy micrometers.
          Mike

          My Dad always said, "If you want people to do things for you on the farm, you have to buy a machine they can sit on that does most of the work."

          Comment


          • #6
            Obviously I am missing something here, perhaps I am using the wrong terminology...

            I would use parallels on my mill to support a workpiece above the table so that I can drill/mill right through without damaging the table.

            Philbur says home-made parallels would only be accurate when used in the same place, and I am sure he is right as obvioulsy nothing is perfect in this world and that includes my mill table.

            Now if the table is not perfect the expensive bought parallels will not be able to compensate for that whereas my home made parallels would be 'more perfect' at least in the position in which they were made.

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            • #7
              Oh good grief. Just use the parallels and quite arguing about minutia.

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              • #8
                Originally posted by Dr Stan
                Oh good grief. Just use the parallels and quite arguing about minutia.

                Nah, thats not my point, I am suggesting that my home shop parallels are just as good and maybe better for my purpose than bought ones.

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                • #9
                  I think it might be good for a one time set-up but for repeated use under different conditions and run of the mill precision you may as well just use ordinary flat bar-stock, I do.

                  Precision parallels, together with a precision mill make close tolerance work quick and easy. If you are good you can do the same quality work without either, it just takes much longer to set it up.

                  Phil

                  Originally posted by The Artful Bodger
                  Obviously I am missing something here, perhaps I am using the wrong terminology...

                  I would use parallels on my mill to support a workpiece above the table so that I can drill/mill right through without damaging the table.

                  Philbur says home-made parallels would only be accurate when used in the same place, and I am sure he is right as obvioulsy nothing is perfect in this world and that includes my mill table.

                  Now if the table is not perfect the expensive bought parallels will not be able to compensate for that whereas my home made parallels would be 'more perfect' at least in the position in which they were made.

                  Comment


                  • #10
                    Agree Bodger, Make em and use em.

                    Comment


                    • #11
                      The object of "parallel" is if mates are matched for size and all are parallel. Everything else is preferential even straightness - if th error isn't excessive. They don't even have to be a particular size; merely parallel half a$$ straight, and the height you need at the moment.

                      For years in my home shop I got along fine with cold rolled steel rectangles. When I first set up I asked a local steel supplier to set aside rems for me and when he got to a ton, call me. In among the rems was a good selection of cold rolled flats and rectangles. Laid out yight together and there was mayne 3 frrt of shelf taken up - maybe a hundred pounds or more of make do set-up tooling. Mike them and they are pretty parallel and even flat and straight. A little judicious dressing with a file and a stone and some scientific peening to straighten and I hade a hell of a collection of parallels all for scrap price. (This was 1971 when steel was cheap.)

                      Anyway, satisfactory home brew parallels are very possible but results depend on the care and foresight with which you make them and since they are soft, the care you employ when you use them - and dress the dings and burrs as you make them.

                      Nowadays in the epoch of cheapo imports I have several thickness sets of hardened and ground parallels but the cold rolled steel ones still have a place.

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                      • #12
                        If they are parallel with in 0.0005 they are good enough for any thing you will do. Even .001 will be alright . I have plenty of home made parallels and they all work just fine. You aren't building rocket ships are air planes. Use them .
                        Every Mans Work Is A Portrait of Him Self
                        http://sites.google.com/site/machinistsite/TWO-BUDDIES
                        http://s178.photobucket.com/user/lan...?sort=3&page=1

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                        • #13
                          I think what Bodger is driving at is that, like soft-jaws on a lathe, his 'parallels' are machined in situ, and therefore necessarily true to the spindle. Repeatability is another question.
                          Last edited by Bryan B; 04-15-2012, 09:09 PM.

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                          • #14
                            Thanks for all the comments.

                            I am sorry if I did not make clear the gist of what I am doing.

                            I am skimming the top surface of the scrap steel blocks to make a surface that is parallel with respect to the movement of the mill head and I am marking these blocks so they will always be used in the same orientation with a view to preserving this accuracy.

                            Dang! Bryan you are right on! That is exactly my message, you posted while I was typing.

                            Comment


                            • #15
                              Originally posted by Forrest Addy
                              The object of "parallel" is if mates are matched for size and all are parallel. Everything else is preferential even straightness - if th error isn't excessive. They don't even have to be a particular size; merely parallel half a$$ straight, and the height you need at the moment.

                              For years in my home shop I got along fine with cold rolled steel rectangles. When I first set up I asked a local steel supplier to set aside rems for me and when he got to a ton, call me. In among the rems was a good selection of cold rolled flats and rectangles. Laid out yight together and there was mayne 3 frrt of shelf taken up - maybe a hundred pounds or more of make do set-up tooling. Mike them and they are pretty parallel and even flat and straight. A little judicious dressing with a file and a stone and some scientific peening to straighten and I hade a hell of a collection of parallels all for scrap price. (This was 1971 when steel was cheap.)

                              Anyway, satisfactory home brew parallels are very possible but results depend on the care and foresight with which you make them and since they are soft, the care you employ when you use them - and dress the dings and burrs as you make them.

                              Nowadays in the epoch of cheapo imports I have several thickness sets of hardened and ground parallels but the cold rolled steel ones still have a place.
                              Forrest:

                              I'd happily pay your price for 10 pounds of anything you thought was straight and parallel.
                              I'm not going to try to make my own though, I've got enough other errors to contend with.
                              Mike

                              My Dad always said, "If you want people to do things for you on the farm, you have to buy a machine they can sit on that does most of the work."

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