Explain bronze bushing to me please
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  1. #1
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    Mar 2006
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    Explain bronze bushing to me please

    Skip this backstory if you just want the meat and potatoes here:

    So, I found a guy on craigslist. He barters machine work for whatever you got. We ended up having a lot of common interests and became friends.

    He had locked up a bronze bushing in his lathe and asked me to help him take the gearbox apart, remove the chuck, remove the shaft.....

    So it seems that the shaft seized up in the bronze bushing. When we got it all apart there was an obvious hot spot on the ID of the bushing. It was cool by the time we got to it and so it wasn't locked up by then. But he had tried to get it all apart before I got there and he broke off some threads on the bushing. Of course it is some Italian lathe from the 1930s or so and no blueprints are available.

    So my part was to help tear down and then pad the bushing with silicon bronze. I TIG welded it, not brazed it. I wanted to have full fusion for when he cut the new threads back down.

    Thats the back story.

    Meat and potatoes:

    What is the bronze bushing being used for? There are huge roller bearings on the shaft already.

    My guess: To take up any endplay or slop in the bearing?
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  2. #2
    Join Date
    Mar 2011
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    Re: Explain bronze bushing to me please

    Without any pics or a diagram it's kinda hard to tell....

    could be for end play... but unless it has a pretty big flange for side loads I would say no.... more than likely for deadening harmonics that the roller bearings would allow to multiply maybe???

    So, what kind of bronze was it? or are you just guessing on the material.

    Did you do any indicator tests with and without the bush?


    I am very curious about the design here as I have a few lathes myself, but only the newer ones have roller bearings on the head.

  3. #3
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    Re: Explain bronze bushing to me please

    I can take a picture and post it.

    I had to completely guess. He said the OEM scrapped all the original documents. Plus, both he and I came up with the same idea, casting a new bushing and cutting a new one from scratch.

    There are bushings on both ends of the shaft.

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    Last edited by Joker11; 07-10-2018 at 11:05 PM.
    Lincoln Power Mig 350MP - MIG and Push-Pull
    Lincoln Precision TIG 275,Undercart cooler,Foot/Finger Amptrollers
    Lincoln Hobby-Weld 110v
    Lincoln SP-200 MIG and Hi-Freq Tig
    CK TIG TORCH, gas diffuser, pyrex cup
    Thermal Dynamics Cutmaster 101

  4. #4
    Join Date
    Aug 2008
    Posts
    11,095

    Re: Explain bronze bushing to me please

    Depending on the diameter of the bushing, might be easier to just buy some 660 bronze round stock, or hollow round, to make the new bushing. 660 is a good quality leaded bronze suitable for bushings. Machines like a dream.

    Be interesting to see how the silicone bronze machines (the stuff you used for padding). My choice would have been a low fuming bronze brazing rod.

  5. #5
    Join Date
    Aug 2008
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    Re: Explain bronze bushing to me please

    On my lathe there are bronze bushings/bearings that rotate either with, or independent, of the spindle shaft. The back gear cluster comes to mind, it rides on the spindle shaft, and is either locked in, or out.

  6. #6
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    Re: Explain bronze bushing to me please

    FarmerSamm,
    I edited the above post and added pics. The shiny part is where he turned down my padding to see how I was doing, checking for porosity and such.

    I had never done bronze before. So this was a mess for me. There was also a miscommunication on one of the bevels. I thought he was going to turn the threads up a bit. So I got right up on it and well, I goofed. He didnt want the padding attached to the bevel . So he has to turn that too.

    I have to go back over the outside edge and pad that so he can have a squared up corner. I felt like I was learning aluminum all over again. All of a sudden, poof, I had a meltdown on the edge. I am changing Tungsten and using a smaller filler rod for this now. I REALLY should have practiced on a piece before I lit up on his part! hahaha. Thank goodness I am padding and he can cut it back down. Go easy on me here. I am not proud of the weld appearance (Glad you cant see those) but the padding seems solid. No inclusions, no porosity, the machining looks like its solid. Comment freely.
    Last edited by Joker11; 07-10-2018 at 11:16 PM.
    Lincoln Power Mig 350MP - MIG and Push-Pull
    Lincoln Precision TIG 275,Undercart cooler,Foot/Finger Amptrollers
    Lincoln Hobby-Weld 110v
    Lincoln SP-200 MIG and Hi-Freq Tig
    CK TIG TORCH, gas diffuser, pyrex cup
    Thermal Dynamics Cutmaster 101

  7. #7
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    Apr 2006
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    Re: Explain bronze bushing to me please

    Are the bearings tapered? The bushing appears to be tapered too, which means that it would be used to set the preload on the bearings.
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  8. #8
    Join Date
    Aug 2008
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    11,095

    Re: Explain bronze bushing to me please

    Quote Originally Posted by Joker11 View Post
    FarmerSamm,
    I edited the above post and added pics. The shiny part is where he turned down my padding to see how I was doing, checking for porosity and such.

    I had never done bronze before. So this was a mess for me. There was also a miscommunication on one of the bevels. I thought he was going to turn the threads up a bit. So I got right up on it and well, I goofed. He didnt want the padding attached to the bevel . So he has to turn that too.

    I have to go back over the outside edge and pad that so he can have a squared up corner. I felt like I was learning aluminum all over again. All of a sudden, poof, I had a meltdown on the edge. I am changing Tungsten and using a smaller filler rod for this now. I REALLY should have practiced on a piece before I lit up on his part! hahaha. Thank goodness I am padding and he can cut it back down. Go easy on me here. I am not proud of the weld appearance (Glad you cant see those) but the padding seems solid. No inclusions, no porosity, the machining looks like its solid. Comment freely.
    The buildup looks fine And it seems to machine beautifully too

    Edges are the pits, hard to control the heat. Sometimes I just walk away, and let the piece cool down, then gently heat the area with a smaller OA tip...just melting the surface, and allowing for the bronze to wet in. But that's using gas apparatus, not TIG. I'm assuming TIG is pretty close though.

    Buildups don't have to look good, all they gotta do is provide enough material to machine back to original specs. Adding too much is not a sin. Having to add more, once you think you're done is a PITA, but pretty common I'd bet.

  9. #9
    Join Date
    Mar 2006
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    Re: Explain bronze bushing to me please

    Quote Originally Posted by scsmith42 View Post
    Are the bearings tapered? The bushing appears to be tapered too, which means that it would be used to set the preload on the bearings.


    Yes, there are two tapers on the bushing. I don’t recall if the bearing were tapered or not.
    Lincoln Power Mig 350MP - MIG and Push-Pull
    Lincoln Precision TIG 275,Undercart cooler,Foot/Finger Amptrollers
    Lincoln Hobby-Weld 110v
    Lincoln SP-200 MIG and Hi-Freq Tig
    CK TIG TORCH, gas diffuser, pyrex cup
    Thermal Dynamics Cutmaster 101

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