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Thread: In Honor of Sir John...

  1. #1
    Join Date
    Mar 2003
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    4,333

    Default In Honor of Sir John...

    I'm rebuilding my old Wellsaw horizontal bandsaw, and one of the tweaks was to fix the wobbly motor pulley. The shaft of the motor, on close inspection, looked like someone had put a file to it as the motor was turning. Measuring it showed I was right- the shaft was, in spots, nearly 20 thou undersized, as well as slightly tapered, and generally egg shaped.



    I tried sending it off to the UK to the experts at this sort of thing, but the box was returned as "undeliverable". Blighter's likely down at the pub having a beer and some sausages.

    So, I decided I'd do it myself. A quick aluminum collar to protect the bearing surface, and piled on the weld- with my recently-resurrected Miller 200 MIG, too.



    Once it was cool, I used the old sod's trick of a steady on the bearing surface to recut the center-drill on the end of the shaft by single-pointing it, and after that, it's a standard turning exercise.



    And done!



    I still need to recut the keyway, but she's done and precisely on spec. Blighter'd be proud, I think.

    Doc.
    Doc's Machine. (Probably not what you expect.)

  2. #2
    Join Date
    Jan 2004
    Location
    Missouri
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    Nice.

    bet you are right......
    1601

    Keep eye on ball.
    Hashim Khan

  3. #3
    Join Date
    Jan 2003
    Location
    On the Oil Coast,USA
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    19,276

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    Nice job,I think he would approve.
    I just need one more tool,just one!

  4. #4

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    A salute to him and to you too. He did some amazing saves on buggered machines and made it look like it was no big deal. It was great that he shared as much as he did - the techniques and the humor.
    .
    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

  5. #5
    Join Date
    Aug 2009
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    Nice job.
    Did you run into any hard spots or pin holes when you were turning it.?

    JL......

  6. #6
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    Aug 2004
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    Quote Originally Posted by Doc Nickel View Post

    Once it was cool, I used the old sod's trick of a steady on the bearing surface to recut the center-drill on the end of the shaft by single-pointing it, and after that, it's a standard turning exercise.

    Doc.
    Nice. Thanks for posting. Good fix. JR
    My old yahoo group. Bridgeport Mill Group

    https://groups.yahoo.com/neo/groups/...port_mill/info

  7. #7
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    Mar 2003
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    Quote Originally Posted by JoeLee View Post
    Did you run into any hard spots or pin holes when you were turning it?
    -There's a vague shadow of the weld at the bearing end...



    ... But that's about it. I was pretty careful to wire-brush between 'coats' (and remembering to let the weld "dry", too ) so there weren't any real inclusions or cold shuts.

    And no hard spots. I did do the welding outside, but the breeze was minimal, and it got pretty hot during the process. I tried to keep it well below "red", and didn't quench anything. Just left it to cool for about an hour before I started the machining.

    My only real worry is a HAZ transition at the base of the bearing step, due to the end of the weld and the aluminum collar. I don't think it'll be an issue, I'm sure the shaft is just mild steel anyway, and like I said, I didn't quench anything.

    In any case, it's only about a 3/4HP motor and on a bandsaw. It shouldn't see a lot of abuse.

    Doc.
    Doc's Machine. (Probably not what you expect.)

  8. #8
    Join Date
    Dec 2007
    Location
    South Wales
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    I dub thee “sir John jr”, arise to defend the humble bandsaw
    Nice job
    Mark

  9. #9
    Join Date
    Dec 2011
    Posts
    636

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    Quote Originally Posted by Doc Nickel View Post
    Once it was cool, I used the old sod's trick of a steady on the bearing surface to recut the center-drill on the end of the shaft by single-pointing it, and after that, it's a standard turning exercise...Doc.
    That looks fantastic. But can you explain in a bit more detail how you go from the blobby welded part to the next image where it's cleanly being machined on the lathe? I missed Sir John's original treatise on the method.

  10. #10
    Join Date
    May 2006
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    14,279

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    Quote Originally Posted by Doc Nickel View Post
    -There's a vague shadow of the weld at the bearing end...

    .
    That's not even worthy of being called a clumsy bastard in fact I think he'd overlook that and actually be proud of you - good duty and thanks for bringing the guy up, one of my all time hero's on this site...

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