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Need a little help welding a 120 year old gear.

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  • Need a little help welding a 120 year old gear.

    I am trying to fix a old machine for winding the cord onto a net making needle or shuttle. I just want to make it presentable for donating it to a maritime museum. One of the gears is broken, a 4.5 inch cast iron gear is broken.
    I think I can braze it after grinding out a little V in the breaks. I have found a hose clamp that will hold it all in place.]There are going to be 5 places to weld. After clamping it all together I had a hard time locating the breaks. My question is, would it help to preheat the gear before gas welding it. (a gas welder is all I have) and then slowly let it cool off.. What are some suggestions?
    Last edited by lugnut; 08-10-2016, 02:28 AM.
    _____________________________________________

    I would rather have tools that I never use, than not have a tool I need.

  • #2
    I guess I need more help. why did my photos show as linkds?
    _____________________________________________

    I would rather have tools that I never use, than not have a tool I need.

    Comment


    • #3
      Originally posted by lugnut View Post
      I guess I need more help. why did my photos show as linkds?
      Yep, photos show up as links, but the links work fine for me, anyhow.

      Comment


      • #4
        Your proposal matches the most common advice for the repair. Clean, V, braze. If you V it, the braze will show.

        If it's just for show, you could even glue it since it will not be used as a gear.

        Dan
        At the end of the project, there is a profound difference between spare parts and extra parts.

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        • #5
          Are you going to braze it or gas weld it.
          You are not clear.

          -Doozer
          DZER

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          • #6
            Originally posted by danlb View Post
            If it's just for show, you could even glue it since it will not be used as a gear.

            Dan
            If indeed this is just for show, this would be my suggestion.

            If the museum actually wanted to use the machine, I wonder if you could find an iron caster willing to cast a gear for you and let them use the gear as a pattern? There seems to be a number of hobbyists who cast and a few who cast iron. Just a thought.

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            • #7
              Originally posted by Doozer View Post
              Are you going to braze it or gas weld it.
              You are not clear.

              -Doozer
              He is proposing to braze it, but is using terms rather loosely.

              Brazing will show, but for a museum, that is not all bad. They are usually OK with, and even prefer, obvious repairs vs concealed ones. If for any reason the repair was wanted hidden, I suspect it could be covered with some sort of "grunge in lacquer" paint.
              1601

              Keep eye on ball.
              Hashim Khan

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              • #8
                Originally posted by danlb View Post
                If it's just for show, you could even glue it since it will not be used as a gear.
                If you wanted to hide the brazing, you could paint it with cast iron colored paint. I think Eastwood carries it.

                As 'spindly' as it is, I would most definitely want it to cool off quite slowly and evenly.

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                • #9
                  Old CI parts like that usually have a lot of 'juice' in them. I've found that sandblasting the part to remove the visible junk, followed by heating to about 400*F in the oven to cook out the 'juice', the blast the joints to remove the cooked out juice
                  give a good surface for the braze. I've had excellent success as prep for both brass brazing and silver brazing, either of which
                  I would recommend for this little gear. The last gear I repaired by silver brazing was 16"dia.

                  No special pre-heat required with either process, just let the part cool in still air.

                  Pete
                  1973 SB 10K .
                  BenchMaster mill.

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                  • #10
                    If the gear is to be used, can it be repaired, really? How round would it likely end up?

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                    • #11
                      Dan, I have to make usable, I know sure as heck, someone will want to give that crank handle a turn . I have even gone to the trouble to make a needle/shuttle to show what the thing does.
                      _____________________________________________

                      I would rather have tools that I never use, than not have a tool I need.

                      Comment


                      • #12
                        For a museum piece

                        Silver braze (silfos) will be fine. Make up some thin preforms. Clean and flux all the bits, band the gear parts with a spring clamp and throw the works in the furnace.
                        Let cool wit the furnace door closed.

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                        • #13
                          If it is going to be used or turned you might contact http://www.martinmodel.com/index.html and see if he could cast a new one from your pattern.

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                          • #14
                            You can select just the .JPG, without the .HTML extension. Right click on the image, select "Copy Image", and then paste (Ctrl-V) into the forum:



                            http://pauleschoen.com/pix/PM08_P76_P54.png

                            Paul: www.peschoen.com
                            P S Technology, Inc. www.pstech-inc.com
                            and Muttley www.muttleydog.com

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                            • #15
                              Posts #9 & #12 would be my approach

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