Working with molybdenum
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  1. #1
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    Default Working with molybdenum

    My parents have a wood stove that they light with one of those waxy fire bricks every cold morning. It's always a bit of a balancing act trying to get one corner of the starter up off of the base to have a surface to light with a match.

    I was thinking that for a late father's day gift I would try and make a small stand out of a refractory metal that could hold these bricks while exposing the lower surface for easy lighting.

    I understand that there are much easier ways to do this, and honestly it's such a minor problem we've never bothered trying to solve it, but I have an interest in these types of metals and it would be a neat gift regardless.

    So my question is, how difficult is molybdenum to work with? I would likely be using 0.047" thick pure Mo sheet and would like to form it into a sort of box if possible. I would be using a 1/4" radius punch and probably 7/8" V die, with urethane die film, to a 135 degree obtuse angle. I am having a hard time finding a description of the brittleness of this metal.

    Also, is this possible to plasma cut or shear, or what? I will be ordering a square of material large enough to do a few tests, but I would like to have some idea of what I am getting into if anybody has worked with this stuff.

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    According to this doc: http://www.molybdenum.com/wp-content...-Machining.pdf

    "Bending - When properly heated, molybdenum can be formed into intricate shapes. Moly sheets less than 0.020” thick can usually be bent at a 180° angle during normal room temperature conditions."

    And later in the same doc, under "Welding":

    "Note that if you weld the pure molybdenum in the open atmosphere, the material is at risk of absorbing the nitrogen and oxygen, thus causing oxidation and causing brittleness."

    So one gets the idea you should use a shielding gas if heating it significantly.

    I've only machined moly, not formed it. Good luck.

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    Stainless would work as well and a lot less potential problems

    Tom

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    Quote Originally Posted by TDegenhart View Post
    Stainless would work as well and a lot less potential problems

    Tom
    and a whole lot cheaper!

    we spin moly . has to be hot worked . we laser cut it , not sure about plasma (shears can fracture it , it doesn't waterjet cleanly) .edges have to be smooth to avoid fracture growth.

    even inconel would be easier to use.

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    nichrome and inconel are metals engineered for high temp. service, but even these, when subjected to the alternate reducing/oxidizing atmosphere of a wood stove hearth won't do well in thin sections.
    its hard to beat cast iron, time proven and cheap. seriously doubt pure moly would be remotely cost effective.

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    The great Swammi sees a small cast iron grate and four bolts (3/8"?) for legs.

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    I'd think a small cast iron trivet or furniture for pottery firing could be perfect.

    High Load | Bed Bath and Beyond

    2" Thick Square Kiln Post, 2" Tall

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    I use a pinecone and a self lighting propane torch.
    Bill D

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    Quote Originally Posted by Bill D View Post
    I use a pinecone and a self lighting propane torch.
    Bill D
    Nah.

    MAPP gas, here.

    It's PM.

    We have higher standards to uphold than the average redneck!

    Using a "Red Dragon" (100% US-made, despite the Chinese-sounding name) don' need no steenkin' pinecones,..

    ...but is serious cheating!



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    Quote Originally Posted by thermite View Post
    Nah.

    MAPP gas, here.

    It's PM.

    We have higher standards to uphold than the average redneck!

    Using a "Red Dragon" (100% US-made, despite the Chinese-sounding name) don' need no steenkin' pinecones,..

    ...but is serious cheating!


    It's not serious until LOX get's involved.......

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    I would just get some stainless tube or rod. Drill a few holes in a firebrick and bend the rod to make a elevated grill. Or just drill some cross holes connecting in the firebrick. Perhaps a old cast iron gas stove burner or grate.
    Bil lD

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    Quote Originally Posted by digger doug View Post
    It's not serious until LOX get's involved.......
    I do not bring my actelyne set with me when I go camping or have a picnic barbecue. A small propane torch, sure.
    Bil lD

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    Thank you for all of the alternatives, which I will probably pursue when this doesn't work.

    The goal here is to place two logs and a fire starter brick, light it, and then let it do its thing. My family is also less industrial in their antics than most folks here.

    To be honest there are a lot of solutions I skipped straight past on my way to molybdenum. Pretty sure I just like molybdenum.

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    Quote Originally Posted by Bill D View Post
    I do not bring my actelyne set with me when I go camping or have a picnic barbecue. A small propane torch, sure.
    Bil lD
    No "acetylene set" needed Mr. "low information voter"

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    Ignoring all of the much more practical solutions, Mo is a really bad choice for this application. In inert atmospheres it is super capable of high-temperature use. In air, however, it oxidizes pretty readily, even at the temperatures in wood fires. Lots of "regular" metals would perform better.

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    Quote Originally Posted by Hightemp View Post
    Ignoring all of the much more practical solutions, Mo is a really bad choice for this application. In inert atmospheres it is super capable of high-temperature use. In air, however, it oxidizes pretty readily, even at the temperatures in wood fires. Lots of "regular" metals would perform better.
    So would a hunk of rock .... or a brickbat.... but "It's PM".

    Why trifle with "the ordinary" when failing at doing things the hard way is so much more interesting!?

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    Yeah, it seems like at the very least I need to choose a different metal.

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    Quote Originally Posted by Strostkovy View Post
    Yeah, it seems like at the very least I need to choose a different metal.
    Just give the folks a supply of sodium and a squirt gun. Instant fire starter...

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    Quote Originally Posted by Strostkovy View Post
    Yeah, it seems like at the very least I need to choose a different metal.
    Too easy by half.

    Use a Moly laser-optics disk OUTSIDE the firebox ....aimed at the kindling.
    Bounce a sore-powerful laser beam off it, and .....

    Or go retro-tech, pre-Columbian Amazonian-Indigenous agro-plantation style:
    Light a naked Brazil nut "meat" and flick it in. No platform required.
    There's a reason their other name is "candlenut".

    Many others among the oilier nuts can be either food or fuel.
    You can literally get this job done for peanuts, even if you have to eat your mistakes.


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