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Thread: replacing cast iron with nylon

  1. #1
    Join Date
    Aug 2002
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    8,009

    Post replacing cast iron with nylon

    I have a small powered hacksaw a neat little table model weighs about 25-30 pounds whilst renovating it having taken it apart,I dropped the drive arm it fell and a piece sheared off one piece of the fork, well I am not in a position to mill one yet (Thrud and Ragarsed will know why I'm smiling) so I made a new arm (perhaps temporary we will see) from a piece of nylon type material, which was originally used as a comercial table top for cutting food. It started life out as a six foot by two and a half foot, by over an inch thick slab.I have made dozens of things with it including bushes and featherboards for woodcutting etc etc etc .It is very strong and workable it wont bend easily so have any of you done anything like this with plastic/nylon before.I would strongly advise anyone who gets the chance to buy a large cutting block like this to go for it .Don't worry about the appearance of it ,although mine was new (because of a change here in the regulations) so even if scratched on the surface it turns and mills beautifully and comes out very clean in no time.I also made a pair of fence faces with it for my home made biesemeyer saw fence.would like to hear if you have tried it Alistair
    Please excuse my typing as I have a form of parkinsons disease

  2. #2
    Join Date
    Mar 2003
    Posts
    426

    Post

    The stiffness or elastic modulus of the best plastics is about 500,000 psi. The stiffness of the worst cast iron is 18,000,000 to 25,000,000 psi. so you are down to less than 1/10th the stiffness of the part that broke off. A good grade of hard wood will be up to 4 times as stiff as plastic but still not close to cast iron. Bottom line: Don't replace steel or iron with plastic for structural members.

  3. #3
    Join Date
    Aug 2002
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    Cass this is no ordinary plastic it is very stiff,however I was suggesting it more as a temporary measure to get you out of a hole till you can make a new one, but to be honest since I have made it I think it would last a long long time.However I think making a proper one in say aluminum later will serve better and be fun to make .I would like to repeat that I do feel this would hold out for a considerable time, after all although it is a functional machine, for all the use it gets from me, it is really just like a little toy compared with the big machines you see although it is very handy.I use it mainly for reducing bolts to size when I daren't put my fingers too near to the wheels of a grinder or worse still try to hold a bolt with a pair of pliers to reduce it on the grinder I know it is foolhardy but I confess I have done it.Alistair
    Please excuse my typing as I have a form of parkinsons disease

  4. #4

    Post

    Alistair

    If it works - great. Besides plastic composites are starting to replace many metals in a great deal of applications these days. Metal is not always better.

  5. #5
    Join Date
    Jan 2002
    Location
    Huntsville Ala
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    5,073

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    Yep. Lotsa things metal would be a poor choice for. Underwear. Toilet paper. Inflatable girlfriends. Condoms. Sleeping bags. Meatloaf. ...er well maybe not, forget meatloaf, that might be a wash.

  6. #6
    Join Date
    Aug 2002
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    Post

    Lynnl what yah talkin about buddy what's wrong with metal under wear Alistair
    Please excuse my typing as I have a form of parkinsons disease

  7. #7
    Join Date
    Aug 2002
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    8,009

    Post

    Or condoms
    Please excuse my typing as I have a form of parkinsons disease

  8. #8

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    Alistair
    I was approached to make a Stainless Steel or Titanium Phallus for a woman I know.

    I told her I don't make metal sculptures of Canadian Members of Parliament - A guy has to have some standards!

  9. #9
    Join Date
    Aug 2002
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    Dave I never saw, or met, or heard, of a Politician who is stainless Alistair
    Please excuse my typing as I have a form of parkinsons disease

  10. #10
    Join Date
    Dec 2002
    Posts
    786

    Post

    Alistair;
    One of the most useful things I made from nylon was a benchblock I milled out for holding the frames of the 45 auto handgun when I used to build them. I machined out places where the frame had projections so the frame would lay flat while I worked on it. With one on each side of the frame it could be place in the vise with no worry of scratching.
    Michael

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