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Cut and weld shaft or cut and make new spline?

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  • Cut and weld shaft or cut and make new spline?

    Rookie wannabe machinist alert!
    My father has acquired an older Johnson 6hp outboard long shaft. We wish to convert it to a short shaft which will require shortening the 'stainless steel' drive shaft.
    I have a 10X22 machine head lathe, but I have very little (if any ) experience.
    I only have an AC stick welder.
    Would I be better to cut a piece out of the shaft and then weld it?
    OR Cut the shaft to the proper length and then use my lathe to make a new spline?
    While I have a good idea how to go about cutting and welding the shaft I really have no idea about how to cut splines using a lathe, or if it is even a good idea?
    I envision clamping the shaft onto the cross slide with some type of cutter in the lathe chuck that will cut the spline grooves?
    Any advice or insight would be appreciated!
    Cheers,
    Jon
    Edit: I looked around for some pictures of the spline and it appears that one end of the shaft only has a key-way and a circlip groove which would likely be easier to replicate then a spline but I am still curious as to what you pro's have to say. The only pics I could find are on this ebay add so it will be down eventually...
    http://www.ebay.com/itm/Johnson-evin...-/300689494545

  • #2
    There is a pretty good discussion here http://bbs.homeshopmachinist.net/thr...utting+splines post # 9 shows a pretty typical mechanism (as an example, there are other photos in other threads, most are a similar variation IIRC).

    It is a problem that comes up fairly often with anyone using older farm or lawn care equipment, generally, I think, the better option is to recut splines. Not that welding can not be done...sort of how much do you trust your skills and what is the part...again, IIRC, splines of odd shapes or patterns are often associated to things like steering and I know I would not trust my welding when control of machine is involved.

    Edit: to add, this, splines, is one area where shapers really shine

    Comment


    • #3
      Jon,

      Given your (very honest) assessment of youe experience level and equipment, my first thought would be to look for a used short drive shaft, on Ebay or elsewhere.

      Failing this, given the choice of weld & cut or shorten & remachine, I'd go for the latter. The 2 main problems you'll have with welding are maintaining straightness and not knowing the properties of the metal you're welding, which might lead to brittleness etc.

      A single keyway can be cut in a lathe, either by laying a suitable cutting tool on its side and racking it back & forth along the bed, or by holding a milling cutter in the spindle and feeding the work in with the cross slide. If using a milling cutter, avoid 'climb milling', where the cutter tries to pull the work in. Feed against the direction of rotation.

      Good luck,

      Ian
      All of the gear, no idea...

      Comment


      • #4
        Not knowing how this shaft is to be assembled I will offer another alternative. Can you cut the shaft and make or buy a coupling to reconnect them. You could turn a sleeve with a keyway and machine the shafts for a corresponding key (maybe woodruff).

        Bob

        Comment


        • #5
          Originally posted by Bob_W View Post
          Not knowing how this shaft is to be assembled I will offer another alternative. Can you cut the shaft and make or buy a coupling to reconnect them. You could turn a sleeve with a keyway and machine the shafts for a corresponding key (maybe woodruff).

          Bob
          Or heat shrinking a tube over the shaft.
          Amount of experience is in direct proportion to the value of broken equipment.

          Comment


          • #6
            How much do you need to shorten it by?

            what sort of diameter is the shaft, difficult to see from the ebay pic, about 5/8"

            I would try this:

            Cut the shaft in half, chuck one piece,face it off and drill it to a nominal size as deep as you can about half the diameter of the shaft, put a chamfer on the end of 45 deg about 1/8".
            Chuck the other half of the shaft and turn a shoulder on it to the nominal diameter you just drilled with the length of the smaller diameter just shorter than the depth you drilled, so when you insert one into the other you have the finished length you want. Put a 45 deg chamger on the shoulder about 1/8"
            Butt the 2 together and weld round the chamfer when you're sure the lenght is correct
            check it's straight, grind up the weld as required to suit.

            Hope that makes sense

            Comment


            • #7
              For me, it would depend on where you are going to use the boat.

              Pottering about a lake, I might cut and shut the shaft.

              If I could, I would have a go at recutting the splines, much more interesting

              Out at sea, I'd buy the right shaft

              Richard

              Comment


              • #8
                "Pottering about in a lake" vs "out at sea." Could I introduce you to Lake Superior and the Edmund Fitzgerald?
                Duffy, Gatineau, Quebec

                Comment


                • #9
                  Originally posted by DickDastardly40 View Post
                  How much do you need to shorten it by?

                  what sort of diameter is the shaft, difficult to see from the ebay pic, about 5/8"

                  I would try this:

                  Cut the shaft in half, chuck one piece,face it off and drill it to a nominal size as deep as you can about half the diameter of the shaft, put a chamfer on the end of 45 deg about 1/8".
                  Chuck the other half of the shaft and turn a shoulder on it to the nominal diameter you just drilled with the length of the smaller diameter just shorter than the depth you drilled, so when you insert one into the other you have the finished length you want. Put a 45 deg chamger on the shoulder about 1/8"
                  Butt the 2 together and weld round the chamfer when you're sure the lenght is correct
                  check it's straight, grind up the weld as required to suit.

                  Hope that makes sense
                  That also sounds like a fun project! since the shaft only ever turns one direction I would not need to weld it either, a bit of locktight and/or a set screw and it would never move... unless it had a backfire I guess....
                  I am not sure of the shaft size yet as I have yet to pull it apart... Once I do I will revive this thread!
                  Cheers,
                  Jon

                  Comment


                  • #10
                    Would you go pottering around Lake Superior?

                    It may be a lake to you, looks more like a bloody great ocean from over here

                    My advice still stands though - if you could die as a result of your work, buy a shaft

                    Richard

                    Comment


                    • #11
                      Looks like you're a little late, Duffy. Should have posted that four days ago. Very interesting and sad though.
                      Richard - SW London, UK, EU.

                      Comment


                      • #12
                        Hmmm... my second post seems to have vanished... here goes again:
                        Thanks for all the input folks!
                        I think I will go ahead and try to machine it, I could shop around for a short shaft but I wont learn anything that way!
                        So it sounds like putting the shaft in the chuck and then moving the carriage back and forth with the tool is the preferred method to do this with a lathe?
                        Will my HSS tool work to cut the stainless steel or do I need to get carbide tooling?
                        This little kicker will be mostly used for putting around on the Vermilion river and nobody's life will be dependant on it.
                        FWIW, I have paddled the north shore of Superior in a canoe and lived to tell about it, not for the faint of heart!
                        Cheers,
                        Jon

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                        • #13
                          Having cut a keyway that way (tool in toolpost, used as a broach) you'll find it's damned hard work

                          I would buy a cutter, put it on a mandrel driven by the chuck and clamp the shaft to the cross-slide, then mill the splines

                          Richard

                          Comment


                          • #14
                            What kind/shape of cutter?
                            The shaft is stainless steel...
                            Cheers,
                            Jon

                            Comment


                            • #15
                              This sort of thing, it will need to match the splines you already have:

                              http://www.ebay.co.uk/itm/NOS-Decovi...-/350608561649

                              Richard

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