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  • Pulley repair

    I have a pulley for the the K&T that looks like it has been dropped and chipped off a 2 inch section of a 4V pulley. Due to the offset a commercial replacement is not really an option.

    The balance of the pulley is a problem. The missing part is the other.

    I could drill weight out of the pulley and rebalance it and then only use three of the Vs.
    I have some nickel rods and could fill in the missing section and turn it back right. I would still have to rebalance.
    The last and not sure if it would hold up is to fill it with brass (braze), turn, and rebalance.

    Any other options I am not thinking of?

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  • #2
    I would clean it up real good lay it on a piece of clean 12 or 14 gauge sheet metal and braze them together filling in the missing piece. Then when cool put it in the lathe and face the sheet metal off leaving the bronze.
    It should be balanced good enough.

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    • #3
      I'm not a repair machinist, but I'm just thinking out loud,
      What if you turned off all the damage until you clean up that bad half of the pulley vee. you would end up with half a vee groove.
      then turn a flange you could press onto that half, and braze it in place, and turn to dress it up as required, very little rebalancing would be need

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      • #4
        My thought is to use a boring head or fly cutter to tidy the broken area into a smooth arc. Then scribe a 2+" long piece of steel the thickness of the heaviest part of pulley with that radius and bandsaw + bench sander it to match the missing area. Similarly, shape the outer edge to be a little larger than the pulley radius. Braze this in place then turn it to remove the excess material. Should be about the same weight as the original so balance should be close.
        Last edited by GadgetBuilder; 06-02-2020, 10:21 AM.
        Location: Newtown, CT USA

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        • #5
          If that’s a multiple-belt pulley as it looks to be, I’d just use it with three belts. Turn off the broken rim if it is too out of balance.

          If the pulley steps are for speed changing, and you need that particular speed, I’d turn the broken are back and screw or braze on a steel plate which I’d then turn to the V profile.

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          • #6
            The 4V are the same size. I like the 12 or 14 gauge thought. I was going to free hand it. If I clamp it down...
            I trying to keep the four Vs to drive this. Will I ever cut that heavy that I need all four. Mostly not but having the option is always good.

            Grinder is the next step.


            Last edited by outlawspeeder; 06-01-2020, 11:41 AM.

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            • #7
              my tripple pulley mill has been running on one belt for 10 years. if it ever slips there will be a reason.

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              • #8
                Hi,

                Either find a salvaged part or face it off and run it with 3 belts. It ain't that big of a problem to need to fix it. Most of those KT's are running with one or two belts these days anyway.
                If you think you understand what is going on, you haven't been paying attention.

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                • #9
                  Dad had a pulley like that get broken and brazed the piece back in and I turned it to fit and it's been running fine. I'd suspect that building that up with braze and recutting it would work fine.
                  21" Royersford Excelsior CamelBack Drillpress Restoration
                  1943 Sidney 16x54 Lathe Restoration

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                  • #10
                    I Wonder if you have problems with the braze sticking to the cast if you could wet it with silver braze first then fill with silicon bronze? Has anyone tried that?

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                    • #11
                      I would cut out the opposite side to sort out the balance and then use three belts. You might have the machinery to completely remove the end. The original design was for heavy industrial use and long belt life which explains the generous overengineering.

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                      • #12
                        Cutting the rest ov flange off, bad idea, it cuts out balanced part and it will be out of balance.
                        I would fab a piece to fit close, braze or weld, then re machine. Careful how you weld, very easy to end up with a very hard weld.

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                        • #13
                          As been mentioned just Machine it off,I run a couple Grain Augers with 1 B width belt 10hp motors with no issues.I recently got a old 2 hp with 4 groove A pulley,that's way overkill.

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                          • #14
                            I had a 4" cast iron pulley frm my lawn tractor that broke just like the one in the picture. I backed the inside with a piece of copper and TIG welded it up. A little lathe work and some hand filing and it's good as new. Still holding 20 years later.

                            JL..............

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                            • #15
                              It is possible to build up the flange using cast iron rod with an ocy/acy torch and the proper flux. Afterwards machine away the over-build. I learned recently that cast iron rod can be used with TIG and no flux but have not tried it myself.

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