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Thread: A hole

  1. #1
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    Default A hole

    I bet one of you machinist types knows.

    If there is a hole in a plate of metal, does heating make the hole smaller or larger?

    Same question for cooling.

    I can imagine it both ways.

    Iím trying to drift pins out of a thing and they are galled, corroded, electrolized, or otherwise stuck.

    It might or might not be my pressure cookers.

    Thanks!

  2. #2
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    Default Re: A hole

    the hole expands when the surrounding metal is heated evenly
    Simpler is better, except when complicated looks really cool.

  3. #3
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    Default Re: A hole

    Quote Originally Posted by bluedog225 View Post
    I bet one of you machinist types knows.

    If there is a hole in a plate of metal, does heating make the hole smaller or larger?

    Same question for cooling.

    I can imagine it both ways.

    I’m trying to drift pins out of a thing and they are galled, corroded, electrolized, or otherwise stuck.

    It might or might not be my pressure cookers.

    Thanks!
    Look up the coeficcients of expansion of the metal in the body/lid, and of the metal of the pins.

    Try spot heating the pins with a soldering iron to expamd them. That may break up/crumble the corrosion producrta.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: A hole

    ^ I'm guessing it changes shape, too.
    "Where you live in the world should not determine whether you live in the world." - Bono

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  5. #5
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    Default Re: A hole

    Quote Originally Posted by CWSmith View Post
    ^ I'm guessing it changes shape, too.
    No reason why it would.
    It really is quite difficult to build an ugly wooden boat.

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  6. #6
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    Default Re: A hole

    I would thing with something like a piston, it might compress the hole prior to the block getting hot. So I get the even heating. Thanks.

  7. #7
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    Default Re: A hole

    Try spot heating the pins with a soldering iron to expamd them. That may break up/crumble the corrosion producrta.
    Or, if the configuration allows it, heat the whole up a bit, and then put an ice cube on the pin. Note that that's 'whole,' with an initial 'w.' Cuz you can't heat up a hole. You can only heat up the thing the hole is in.
    Speak softly and carry a mouthful of marbles.

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    Default Re: A hole

    Quote Originally Posted by bluedog225 View Post
    I bet one of you machinist types knows.

    If there is a hole in a plate of metal, does heating make the hole smaller or larger?

    Same question for cooling.

    I can imagine it both ways.

    I’m trying to drift pins out of a thing and they are galled, corroded, electrolized, or otherwise stuck.

    It might or might not be my pressure cookers.

    Thanks!
    Ever see the experiment with a ball and 2 rings. All made of the same material. The inside of one ring shrinks when heated. The inside of the other expands when heated.
    Life is complex.

  9. #9
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    Default Re: A hole

    I think there’s a procedure at Boeing where a large pin is frozen in a nitrogen cask and pressed into a hole within seconds. I don’t believe it’s ever removable.
    ITS CHAOS, BE KIND

  10. #10
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    Default Re: A hole

    Quote Originally Posted by Too Little Time View Post
    The inside of one ring shrinks when heated.
    a metal ring? seems implausible and contrary to the laws of physics, the thermal expansion of rings is defined by the linear expansion of the material
    Simpler is better, except when complicated looks really cool.

  11. #11
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    Default Re: A hole

    Quote Originally Posted by Paul Pless View Post
    a metal ring? seems implausible and contrary to the laws of physics, the thermal expansion of rings is defined by the linear expansion of the material
    That is the beauty of it. Make the ring think enough and it acts like a plate. As others have said there the hole shrinks.
    Life is complex.

  12. #12
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    Default Re: A hole

    i would like to see the specific example that you are citing
    Simpler is better, except when complicated looks really cool.

  13. #13
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    Default Re: A hole

    Quote Originally Posted by CWSmith View Post
    ^ I'm guessing it changes shape, too.
    Quote Originally Posted by Peerie Maa View Post
    No reason why it would.
    Not all holes are round and very few heating sources are uniform.

    However, you made me rethink the problem and I think you are right for the idealized case.
    "Where you live in the world should not determine whether you live in the world." - Bono

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  14. #14
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    Default Re: A hole

    The hole gets bigger when heated. Shrink-fitting is a standard technique for assembling things tightly. Machine for an interference fit, heat the outside bit, cool the inside, put 'em together and let everything come back to to room temperature. Depending on the shape of the part and how you heat it the hole can change shape a little, but in most cases it doesn't matter.
    Last edited by Keith Wilson; 06-06-2022 at 01:33 PM.
    "For a successful technology, reality must take precedence over public relations,
    for nature cannot be fooled."

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  15. #15
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    Default Re: A hole

    much of what you want also depends on the metals you are playing with and their mass. You might be able to get away with heating everything up a nice warm glow and rapidly cooling the pins. They would shrink faster than the plate and should be easier to drive out that way.
    "If you think you are too small to make a difference, try sleeping with a mosquito"

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    Default Re: A hole

    I’ll try heating the alu without melting it. The pin is steel.

    Hard to cool the pin independently.

    Thanks all.

    9E4A4F16-22B5-44EA-B2D8-8F7761D6FE42.jpg

    F38E77DA-C6F5-44E4-BFA5-DDA84661BDED.jpg

  17. #17
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    Default Re: A hole

    I’ve beaten one out. But I’ma little worried about breaking the ears.

    A8F133B8-1BA4-43E4-B10B-D448739263C5.jpg

  18. #18
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    Default Re: A hole

    FWIW, aluminum expands about 2-1/2 times as much as steel when heated the same amount.
    "For a successful technology, reality must take precedence over public relations,
    for nature cannot be fooled."

    Richard Feynman

  19. #19
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    Default Re: A hole

    Excellent. Thanks.

  20. #20
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    Default Re: A hole

    Back when I was a lad and dinosaurs ruled the earth - my very first science teacher had a nice demonstration with a ball and a ring - he didn't invent the demo and he wasn't the last guy to use it -



    I've known SWMBO use the same principles to remove a stuck trumpet mouthpiece using a hot coffee and some ice cream.
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

  21. #21
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    Default Re: A hole

    And the murders began…
    Speak softly and carry a mouthful of marbles.

  22. #22
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    Default Re: A hole

    Did anyone hear the talk on public radio last week around the question of how many holes a straw has? Seems some people think a straw has two holes and some think it has one. What do you guys think?

  23. #23
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    Default Re: A hole

    a straw has one hole
    Simpler is better, except when complicated looks really cool.

  24. #24
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    Default Re: A hole

    Corn kernels don’t enter your body when you eat them.

  25. #25
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    Default Re: A hole

    Quote Originally Posted by bluedog225 View Post
    I’ll try heating the alu without melting it. The pin is steel.

    Hard to cool the pin independently.

    Thanks all.

    9E4A4F16-22B5-44EA-B2D8-8F7761D6FE42.jpg

    F38E77DA-C6F5-44E4-BFA5-DDA84661BDED.jpg
    A lump of dry ice should do it. The opposite of a soldering iron tip.
    It really is quite difficult to build an ugly wooden boat.

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  26. #26
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    Default Re: A hole

    Quote Originally Posted by P.I. Stazzer-Newt View Post
    Back when I was a lad and dinosaurs ruled the earth - my very first science teacher had a nice demonstration with a ball and a ring - he didn't invent the demo and he wasn't the last guy to use it -



    I've known SWMBO use the same principles to remove a stuck trumpet mouthpiece using a hot coffee and some ice cream.
    Some apple of his mother's eye thought it smart to heat the ring, lower the ball in, and then pour cold water on the ring.

    My class found out about that trick when the metal work tutor was asked to get them apart again.
    It really is quite difficult to build an ugly wooden boat.

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  27. #27
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    Default Re: A hole

    I presume the steel doodad with threads is a loose fit on the pin, and the only tight fit is between the pin and the aluminum casting, right?

    Ah, just heat it up with a propane torch and give the pin a lusty whack. I bet it will come out nicely. Make sure you're bashing on the un-knurled end, though.
    "For a successful technology, reality must take precedence over public relations,
    for nature cannot be fooled."

    Richard Feynman

  28. #28
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    Default Re: A hole

    Quote Originally Posted by StevenBauer View Post
    Did anyone hear the talk on public radio last week around the question of how many holes a straw has? Seems some people think a straw has two holes and some think it has one. What do you guys think?
    Quote Originally Posted by Paul Pless View Post
    a straw has one hole
    Yet that’s not what most people think.

  29. #29
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    Default Re: A hole

    Quote Originally Posted by Keith Wilson;[URL="tel:6672968"
    6672968[/URL]]I presume the steel doodad with threads is a loose fit on the pin, and the only tight fit is between the pin and the aluminum casting, right?

    Ah, just heat it up with a propane torch and give the pin a lusty whack. I bet it will come out nicely. Make sure you're bashing on the un-knurled end, though.
    yep and yep. It’s out baking in the sun right now. Will break out the propane a little later.

  30. #30
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    Default Re: A hole

    How can straws not have two holes? They have two ends!

    Another benefit of heat....it melts Loctite.
    One of the most enduring qualities of an old wooden boat is the smell it imparts to your clothing.

  31. #31
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    Default Re: A hole

    Quote Originally Posted by StevenBauer View Post
    Yet that’s not what most people think.
    Only one. Topology says so.
    It really is quite difficult to build an ugly wooden boat.

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  32. #32
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    Default Re: A hole

    Can’t find my propane or mapp. Everything is up a the place. Big downside of cleaning the place out.

    Went ahead and put it on the gas stove. The first one tapped right out with no drama.

    Thanks all!

    edit-and they are all done. Piece of cake. You guys are experts at….this.
    Last edited by bluedog225; 06-06-2022 at 03:43 PM.

  33. #33
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    Default Re: A hole

    Quote Originally Posted by StevenBauer View Post
    Did anyone hear the talk on public radio last week around the question of how many holes a straw has? Seems some people think a straw has two holes and some think it has one. What do you guys think?
    Depends on who you ask.

    The engineer will say one.

    But some highbrow mathematician (n-space geometer?) will come along and tell you it has infinity.
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  34. #34
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    Default Re: A hole

    Quote Originally Posted by bluedog225 View Post
    You guys are experts atÖ.this.
    that makes us ahole specialists?
    Simpler is better, except when complicated looks really cool.

  35. #35
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    Default Re: A hole

    How many entrances does an elevator in a two story building have?
    Speak softly and carry a mouthful of marbles.

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