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Little reference cone in drawings - whatsit called, whyzit there ?

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  • Little reference cone in drawings - whatsit called, whyzit there ?

    In looking at various drawings for dinguses, I began to notice a small truncated cone is often inserted. I have tried to find it on Google, but I can't hit a combination of search terms that narrows it down well enough to get less than 1,000,000 hits almost all of which are useless to my purpose.

    So, I turn to you guys... What is the little cone called, and why is it there?


  • #2
    That cone tells you whether the drawing is right hand or left hand projection.
    Brian Rupnow
    Design engineer
    Barrie, Ontario, Canada

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    • #3
      See if this works for You
      http://www.technologystudent.com/designpro/ortho1.htm

      HM

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      • #4
        Yeah, it's the symbol for "Third Angle Projection" arrangement of the views. AND IT'S ASS BACKWARDS. Grrrrr.

        And the link site says that 1st angle is mostly Europe and 3rd angle is US. I call BS on that. It's backwards. When I learned drafting back around '60 there was no such thing as 3rd angle.

        Pete
        Last edited by 10KPete; 11-20-2017, 08:14 PM.
        1973 SB 10K .
        BenchMaster mill.

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        • #5
          When I worked for Volkswagen of Canada, many of the drawings I worked with originated in Germany. What a mind blowing experience, after working 30 years with the third angle projection used in North America to try and make sense of beautiful drawings, all as Pete says, "ass backwards" in first angle projection.
          Last edited by brian Rupnow; 11-20-2017, 08:36 PM.
          Brian Rupnow
          Design engineer
          Barrie, Ontario, Canada

          Comment


          • #6
            For those who are bewildered by the discussion, First Angle projections are common in Europe.
            Third Angle projections of parts are used by America.
            First the Third Angle and what it means
            To understand how this works, consider a deep clear glass bowl with your part at the bottom.
            When you look at a drawing , any "View" (image) is considered to be at the BOTTOM of the bowl.
            Now the surface of the part touching the bowl, must stay in contact with it ( Important in this illustration !)
            if you drag the part to the right , it will climb the bowl and you will see the "Right Side" of it - and the surface you were viewing will be on its left. (close to the original view) . Instead of going to the left in the original view we just explained, if you move it forward (away from you) and up , it will roll up the bowl and is called a top view and the portion or view we were looking at is now at the bottom of that view. So to understand any drawing in Third Order projection, always consider what you are seeing is a part at the bottom of as bowl

            Now First Angle. Instead of being at the bottom of a bowl, flip the bowl over ( upside down ) and place the part on the center raised part of the bowl.
            If you slide the part to the right, it will slide down the bowl and you will now see what was the left side of the part you were looking at.

            That is the crux of the disagreement on what's best. First or Third ?
            What gives you the best feel.

            Now look at the cones in the Ops paragraph
            Place the tapered image on the upside down bowl 's center , and then slide it down to the right and you will see the image on the right shown.
            It is a First Degree Projection

            Rich
            Green Bay, WI

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            • #7
              When you lay out 3 standard view with third angle projection, view of the Top of the part is located ABOVE the Front view.
              The view of the right side of the part is located to the RIGHT of the front view.
              Makes perfect sense to me.

              First angle projection puts the top view below the front view and the right view to the left of the front view.
              Not so much sense there.

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              • #8
                I must be loosing it.... MY post is calling it backwards!! And the sad part is I don't have any clear memory of what was called when or where. Yeah, that's it, oldtimers disease!

                Sorry for the mess,

                Pete

                Originally posted by 10KPete View Post
                Yeah, it's the symbol for "Third Angle Projection" arrangement of the views. AND IT'S ASS BACKWARDS. Grrrrr.

                And the link site says that 1st angle is mostly Europe and 3rd angle is US. I call BS on that. It's backwards. When I learned drafting back around '60 there was no such thing as 3rd angle.

                Pete
                1973 SB 10K .
                BenchMaster mill.

                Comment


                • #9
                  The drawing and the symbol are correct. Most common in Europe and on metric drawings. On this particular part it makes no difference. If it was an American projection the cone would have the small dia on the right side.

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                  • #10
                    When I worked for Fred, we made replacement parts for wrapping machines for the poultry industry. One of those machines was Japanese, and I came into possession of a service manual. The parts diagrams were simply reduced copies of the working drawings. I found myself translating Japanese, metric, first angle projections into English, SAE, third angle drawings. I never did figure out some of the drawing conventions, but the parts were acceptable.
                    It's all mind over matter.
                    If you don't mind, it don't matter.

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