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Thread: Bronze or brass

  1. #1
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    Default Bronze or brass

    I am building a small hand operated press the ram will be bright bar approx 25mm diam. the main body will be 6mm mild steel, the the platen will be heated to approx. 300deg c
    should I use brass or phosphor bronze for the bushing the ram will slide in

  2. #2
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    Phosphor bronze or aluminium bronze are much better bearings than brass. but I don't think in that application it's going to make much difference, I'd use what I had.

  3. #3
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    Thanks for that I thought it would not be critical, really just so the ram is not sliding steel to steel, I found out the hard way years ago that is not ideal

  4. #4
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    Hi China,

    You could also use Acetal ! Its surprising how many low and medium loads use plastic bushes. Though in your case, if the shaft is going to get hot Acetal might not be suitable.
    Best Regards:
    Baron J.

  5. #5
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    I don't think China will be working hard enough for the shaft to get hot!!!
    A lot of the hand presses are made of cast, so you could use a bit of cast bar, something like a weight out of a casement window (????). (the old type of vertical sliding window).
    Kryn
    To grow old is mandatory, growing up is optional.

  6. #6
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    Hi Kryn,

    China mentioned that the platen was going to be heated to 300 C, that's why I made my last comment.

    When I've moulded nuts using Acetal, it doesn't seem too long before the plastic starts to melt and form around the threads.
    Best Regards:
    Baron J.

  7. #7
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    Regardless of what the bearing material is, at 300 degrees any grease will melt away. You could use steel on steel if lubrication was present as part of it's purpose is to prevent direct metal to metal contact. If the ram contact is only going to be brief (a few seconds) you could probably get away with it. If you are going to bring the ram down and leave it there while the item on the platten cools, then some form of isolating the sliding bearing from heat result in a far more reliable system.
    I would vote for Phos. Bronze myself but the lubrication problem will still exist (and for light use, brass would probably work too).

    Michael

  8. #8
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    if its hand operated I would just use steel on steel
    my swaging (for hard lead) press is just steel on steel

  9. #9
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    Quote Originally Posted by Michael G View Post
    Regardless of what the bearing material is, at 300 degrees any grease will melt away. You could use steel on steel if lubrication was present as part of it's purpose is to prevent direct metal to metal contact. If the ram contact is only going to be brief (a few seconds) you could probably get away with it. If you are going to bring the ram down and leave it there while the item on the platten cools, then some form of isolating the sliding bearing from heat result in a far more reliable system.
    I would vote for Phos. Bronze myself but the lubrication problem will still exist (and for light use, brass would probably work too).

    Michael
    Not all grease. Try this stuff: https://www.blackwoods.com.au/lubric...SAAEgIux_D_BwE

    I've used this for years on slow moving shafts like covered leadscrews. It's quite amazing. Long lasting, but very messy/dirty stuff to handle.

    I haven't tried it at temperatures they quote, but apparently it can be used on furnace door hinges etc.

    Cheers Rob
    The worst that can happen is you will fail.
    But at least you tried.



  10. #10
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    I have some of the Loctite Anti Seize never thought of using it as a lubricant. The ram will be connected to the heated platen so there is little doubt that is will get hot
    just how hot I will not know until I get it up and running, 300deg is the maximum it will ever run at so the anti seize should be more than adequate, I may just go steel to steel
    it will make things a lot simpler

  11. #11
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    It's a totally different product to regular high temp grease.

    It has a metallic/possibly graphite component that forms a bonded surface layer with steel, bronze etc. So it stays in place and doesn't dilute like grease. On the lathe there is absolutely no metal bleeding from the half nuts as with regular grease. Wear is zero. But as I said, it is very dirty/messy stuff if you get it on you. So best to use in covered areas. I recently used it on the 4 x 6 metal band saw blade idler pulley bush and it seems to be doing good. Regular grease just disappears over time.

    It should do the job.

    Cheers Rob
    The worst that can happen is you will fail.
    But at least you tried.



  12. #12
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    I've used a similar product, Nevew Seize. I used to use it on Blower Shafts in a powder coating oven. Bearings didn't last long, about 6 months max. The bearings were a real pain to get off, until I started using Never Seize, bearings didn't last any longer, but were a lot easier to get off.
    Kryn
    To grow old is mandatory, growing up is optional.

  13. #13
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    Some cast iron would be my choice instead of steel on steel .Depending on the length of the bush you could use an old brake disc machine a couple bushes and press them in on top of each other .Could also have a small space between them to fill with Never seize

  14. #14
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    Don't use a lubricant with an extreme pressure additive that contains sulphur. They turns the copper in brass or bronze into copper sulphide and will do it faster the higher the temperature.

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