casting copper
 

Talking with dad the other day, I found out that molten copper doesn't stick to steel, so today I drilled a hole in a chink of steel, and melted some CU into it. Success! came right out with a few hammer taps.

So now, I'm thnking of making a mold outta a chunk of steel (I got any thickness of steel I'd need... trust me), and then melting all the scrap copper I have (collapsed pipes, etc).

Only problem, I'm having a hard time milling out the copper mold! I have a 3/4 inch bit spinning @ 1137 RPM, and it didn't cut it, and screeced and chatter like a bitch. So I slowed it down to 300 RPM, went a little better, but something wasn't cutting right.

Anyway, what RPM's should I run the mill bit at?

thankyou

-,e

I did some searching last night on machinint steele,

somethings you need to find out,
are you trying to machine hardened steele? If so... STOP! Its not really gonna work.

if your getting chatter, speed up the RPM`s. Also what feed rate are U using? Maybe slowing down the feedrate some should help.

Also make sure your using some sort of cooling. either spray mist or flood coolant. Temps at the cutting plain can exceed 1,000 C

adjust your feed rate and RPM`s untill you are getting good sized chips.

I know you are wanting exact numbers, but that really cant happen.

Also make sure you are using a sharp endmill. If you dont know aobut th endmill, then get a new one. Also your material needs to be clamped down really good.

MAN what a concept! molding an wb instead of milling it.... gl hf on getting the bottom flat though.

thanx guys,

I'm making the think thicker than I need so I can machine it off for a pefect edge;)

I tried casting the SpirAls at one time. We had one done, and I finished the block on the machine to make it fit specs. And saddly, There was to much air in the copper mix and when I took the base of the block down, it leaked like a shower head. That turned me off on the whole idea. I hope you have better luck. What are u using to melt your copper ? I know it takes about 800 degrees to melt it, and what about air bubbles in the melt? Have you gotten any?

Good luck.

yeah forgot about that. try bendning an ordinary drill, and using your electric drill to make enough vibrations for the air to escape. molten ccopepr doesnt have that much of "whatever it is that makes water being able to be higher than "end" of a glass <-- my bad english"
or a dildo if you have one, but i doubt that.

A dildo huh, I know where I can get one of those..... "Hey Joe can I borrow one?"

OMG LOL. he wont be too happy about that :D

What would you use to melt the copper?

I've decided to scrap the idea for now, I ran out of acetelyne to melt the stuff down... oh well

I was thinking of drilling holes in the bottom, for an air escape, which would aid in removale from the mold cause i could out a nail in there and pop it out ;)

but I'll see after I get some aceltlyne

unless you are melting and pouring the copper in a controlled envirement(ie, no oxygen) you are always going to get air pockets. i t doesnt matter how many holes you put in the casting to let oxygen out.
oxygen attaches to the molten Cu at a molecular level.
you have to devise a way to control the processing envirement before you can get good results with casting Cu.
you must remove the oxygen in the atmosphere first.:shrug:
why do you think steel, and misc. metal companies and manufacturers spend so much money on equipement? because if it were as simple as heating the element to melting point and pouring it in a mold, then everyone and their brother would be casting their own metals instead of paying out the ying-yang for it. copper is probably the worst metal to cast with, especially when you need it to be 99% conductive and oxygen free.
i hate to rain on you parade. but i can tell you that you are wasting your time. not trying to be an A$$hole, but thats just the way it is unless you have the proper equipement. i have a large amount of copper shaving that i am saving in hopes of figuring a way to do this very same thing and casting it oxygen free.
ive done alot of research on the subject and i can tell you that it is not going to be an easy or inexpensive project!

physics is a bitch aint it?

Gee you dont have to be such an A hole about it...........







JUST KIDDING! Yeah I know a bit about casting copper, from my jounrneys at a machine shop, and wanting to cast the Spir@ls. Its easyer to just machine them, and then that aint so easy either.

We ought to get Bruno Facca in here: he seems to be doing well with his casting process. I'll shoot him an e-mail.

In the mean time, here's his thread .

i bet if bruno were to cut deeper into the base of a casting (say .5" or so) then he to would discover air pockets visible without a microscope. there is NO WAY to pour copper without getting air pockets in it, other than to control the atmosphere that its cast in. or to cast it in really thin peices which still results in air pockets, although very small.
Absolutely NO WAY. you cant beat physics man. i dont care how determined you are!
the thinner the peice cast ,the less air molecules...hence, smaller air pockets that may not be visible to the naked eye. now take that same peice that you cast thin , and look at it under a microscope. thats a lotta pockets huh?

please somebody prove me wrong;)

But could you cast thicker, and thin out the base?

Alright, what about pushing some other gas into the mold before pouring. What is a gas that doesnt bond with Cu at a molecular level? Use it as a shielding gas (similar to welding). Just vent some of that in there, then pour away!

Now you get to tell me why it wont work...

something to that effect would work. as i stated before....you cant pour copper without controlling the oxygen content and expect it not to have pockets of oxygen.
and as far as casting thicker but thinning the base........
that would be defeating the purpose. everything copper above the base would not be as thermally conductive because of the high oxygen content, and a very large percentage of the surface area above the base would be useless. you might as well make one out of aluminum.as it would be more conductive for our purposes if poured in the same manner.
look im not trying to rattle anyones cage. im just trying to save the guy who started this thread some time and wasted copper.

i dont really know of a way to cast copper without spending hunreds of thousands of dollars for the proper equipement to do it without contamination. if there were a way, dont you think there would be a hell of alot of companies that make these type furnaces out of business?
i dont know, but logic tells me it cant be done any cheaper.

Oh crap! I've been writing for about 40 minutes, explorer crashed and I lost everything, damnit!! :mad: :mad: :mad:
I'll rewrite it all tonight.
It's very hard to be able to cast copper without air bubbles but it's possible and I'm doing it for some time now. Also tomorrow (or the day after) I'll have detailed performance info on my cast copper blocks.
I'll be back tonight to explain how to get the air out.

Bruno

Let me start by saying that the process of casting copper, mainly getting a blast furnace that can make and mantain that much heat requires months of work and a lot of trial and error. You also spent a LOT of fuel (whatever you use) to get the copper to the right temp, wich is far from 800 C, actually 800 C would be the temp for brass (I guess that is the name of that "yellow" metal in english, that is 50% copper 50% zinc or chrome I can't quite remember) . It may worth it if you want to make several blocks but if you only want to make one or two for yourself I think there are better methods, I'm not sure you'll get the same results, mainly with the roughness of the inside surface but that depends on a lot of things. If you are planning on doing a lot of them, well, you're competition for me wich is not good for business :).. I know some people (like me) just have to "do stuff themselves" instead of buying it so you'll probably do it anyway no matter what I say. I made that joke about competition but it's kind of true, I spent a lot of time and effort going after people that could teach me better casting techniques so I can make my blocks, if I were to share everything I learned my company (wich is starting out) would be dead before it's "officially born".
Copper can be a real bitch to work with in almost every way, casting it is not an exception, it's hard to cast pieces without any air in it or "smooth edges" you get when the air stays "around" the Cu mass inside the mold. There are a couple of things that can be done to avoid that: the most important are the air exits in your mold, they have to be put in the right spot and they have to be the right diameter, if they're too thin the air won't get out in time, if they're too large too much copper will escape trough them. Another thing is, copper melts at 1085 C, but at this temperature it's not completely liquid, it's kind of "sticky", you have to get it to around 1300 C, at that temperature it's as liquid as water (of course it's a lot heavier) so any air inside it just get out like it would get out of most liquids. Once the copper is totally liquified you have to "swirl" it inside the "bucket" so any impurities stay on top of it, as it's a very dense metal (8,9g per cubic centimeter), you just take out the impurities (if there are any) with a kind of spoon that is made especially for this.
I have been casting several water blocks without any air bubbles, I already took some of them and sanded them until they literally dissapear (turn into a bunch of copper dust) without finding one single air pocket. It's the result of the combination of the right temperature, appropriate air exits in the mold, pouring it at the mold at an appropriate speed (so it doesn't have time to cool down and trap any bubbles) and I guess the molding material I use. When you use steel it absorbs a big part of the heat of the melted copper as soon as you start pouring it in the mold so it may cool down too quickly, in that case the air doesn't have time to get out and you get those nasty air bubbles. I use something we call "green sand" here in my country, it doesn't conducts any heat so the copper takes some time to cool down after it's poured in the mold.

Thank you Bruno, that was very informative, without revealing too much to allow just anyone else to start competing with you!

Thanks for stoping by!

Ok LiquidRulez, care to counter?

ok bruno.......just break out your 20X magnifying glass or a microscope next time you think you see no air pockets, and then come back to the forum and let us know what you find, O.K?
boy are you guys going to be surprised with the results, as Ive already been under the misguided perception that bruno is under too....that just cause I cant see them without a scope of some sort, that they are not there! ! !
they are there you just cant see them with the naked eye.
Even C110 has many air pockets!


Beyond those statements..............I give up!!

Hum... if you need a mag lens or a microscope, and if C110 has the same bubbles, then it might not affect performance very much, if at all...

It would be very interesting to see one of Bruno's cast copper blocks against a milled C110 version.

Sorry for taking so long to reply, I've been so busy with the production I barely have time to breathe :D, but that's a good thing..
I don't have a microscope at home, only a magnifying glass that has some light on it that I use to read small letters on electronic components as zener diodes and stuff, I couldn't see any air pocket with it but I don't know if I would see them with a microscope as I didn't try it. I also think bigben2k has a point.
I guess 0.11 C/W is a good number for a waterblock, that is the result I got from testing it but it's not a definitive number as my testing method was not totally right, on the other side I only added half of the heat dissiped by the pump so maybe it will stay around that.

Bruno Facca

Well, just test the block with high pressure water for a period of time, just to make sure any microscopic air pockets don't connect in a way that the copper would leak water.

There could be air pockets, but as long as they are small enough, and don't cause a leak, it shoudn't matter. The only thing left is comparison of your cast copper to copper bought from a supplier.