First project pics and a couple of questions

Yeah, I'm finally getting some things made in the shop! These ones are from the first couple of weeks - exciting to me, but it's really just a few slots in squared pieces. I'll take the new ones home next weekend and take some more pictures. Pics are at

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Today I did a dovetail slot. It was a little hard on the nerves. Up until this point if the mill started doing something unexpected I could just back the cutter off while I figured out what was going on.

I'm really loving this school thing. Tonight I spent three hours reading about iron ore, coke, blast furnaces, smelters... I'm already itching to get back into the shop on Monday.

While doing that reading and working on some questions from our textbook I came up with three questions... I know you guys know your stuff and I'm hoping you can help me out.

Are all ferrous metals magnetic? I'd think yes, since iron is magnetic, but are there any exceptions?

What is creep strength?

What's the difference between ductility and malleability? I know the textbook answer - ductile metals can be drawn out into a wire without breaking, and malleable metals can be pounded or rolled into shape without breaking. But I don't know why a metal that could be drawn out into a wire couldn't be rolled out or hammered into a shape as well.

chem

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chem
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Chem Looks like a good start.

As to your questi> Yeah, I'm finally getting some things made in the shop! These ones are

Reply to
James P Crombie

Thanks James. :)

Ahh, a magnet. I'll dig one up and do that on Monday.

That link was a good definition of creep strength. I read about it in the Machinery's handbook, but a lot of the stuff in there is still over my head.

I'm still muddy on the ductility vs. malleability thing. If something could be stretched out, I just don't see why it couldn't be rolled out too, although I can see why it woudn't necessarily work the other way. Maybe I'll have to just be happy with the textbook definitions for now and sometime down the road I'll really understand it. :) Oh, wait... Are most metals that are ductile malleable as well? Because that would make it easier to understand...

chem

James P Crombie wrote:

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chem

Metals in general are malleable and ductile... Maybe it would help to think of dry or weak clay. You can press it into shape - it's malleable

- but for the life of you, you just can't pull on it at all without it breaking up. It has no ductility.

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

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Reply to
Tim Williams

Yeah, that's I was kind of getting at... I'm wondering if all ductile metals are malleable, because usually if you can stretch something out you can also press/roll/pound it into shape. All the materials I can think of anyway, but that's really not many.

But I can understand that a malleable metal isn't necessarily going to be ductile as well.

not even sure I'm making sense... :)

chem

Tim Williams wrote:

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chem

Consider a lead bar. You can beat it into just about any shape you want, so it is malleable. But try to draw it out into wire, it'll break. (Lead wire is generally extruded instead of drawn.)

Gary

Reply to
Gary Coffman

Ok, I guess I'm not making sense yet. I understand that things that are malleable aren't necessarily ductile. I can get that part. That's pretty clear to me.

What I really want to know now: Are all ductile metals malleable as well, and if not, why?

chem

Gary Coffman wrote:

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chem

I get what you mean... like concrete is 5 or 10 times stronger (or more? I forget) in compression than tension. Of course it doesn't deform, it just breaks.. so think of it as the yield point instead. :) Conversely, a piece of string or rope can be very strong in tension, but for the life of it won't hold any compression at all. (Of course, that's because it's long and flexible, so nowhere near the same idea, but... you know what I mean... right?...)

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

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Reply to
Tim Williams

Ahh, of course... I hadn't thought of rope and string. So things that are very flexible may not be malleable because they'll just spring back to their previous shape? I think I'll check a book out of the library at school on Monday and try to straighten all this stuff out. :)

chem

ps - nice web page. Pictured you as be>

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chem

Hmm, hadn't thought of it that way. Any inputs from Ed Huntress? Maybe something covering titanium? Rumor has it that stuff is a bitch to roll down...

Thanks.

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

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Reply to
Tim Williams

Nothing from Ed Huntress. And I'll keep titanium in mind when I hit the library tomorrow :)

chem

Tim Williams wrote:

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chem

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