Smelting alum brass copper ?

I picked up a metal lathe awhile back and been learning to use if for a few months now making simple items I needed for the shop like top punch for my sizer. And I went to price some alum billet 45 bucks for a 2 inch dia 24 inch long to costly to practice on for me. Heck I am cheap main reason I started reloading to save money still working on that plan.
So I got to looking into making my own with scrap so I built me a oil fired burner with a blower and all the items needed to melt it down.
So what I have learned so far all scrap is not the same my first melt was everything from drink cans gutters and what ever piece of alum I had laying around. What I got was alum that was worthless to turn it tore instead of cut and ripped out chunks.
My next try I added some brass to the mix what I got would turn and was fair to work with or practice I cast this batch in green sand I made up my self. Big problem I found was voids right down to the middle not some that would turn out. I degassed and fluxed and my temp was high enough as far as I could tell.
My third try I used some tanks that were tested at 3000 psi nothing added my thinking was it had to be a better grade of metal. Well I got my green sand ready to cast and a few pieces of pipe with no weld seam to fill. I poured several different sizes so I would have a mix to pick from for my stock. All looked well until I chucked up one of the green sand pour to clean it up and see what I had to work with. It cut will and I got nice chips with a smooth finish but voids not as many but still to many to use it for anything useful. I was getting kind of down about the entire effort and decided to check out one I pour in the pipe. I had two voids and it turned very well cutting clean and smooth only issue I found was I would get a mirror finish for a section then dull then mirror again. I think this was caused by a chip rubbing work piece but as of now I am just trying to get workable material.
So I think the voids in the green sand casting was moisture in the sand causing the void oh my homemade green sand is well sand cat litter and water until it holds it shape not oil or store bought casting sand. The voids in the pipe one I think was cutting oil or chip left in the pipe since they were right at the out side of the material.

I have seen U Tube where people have cast different item with sand and turn it on a lath to make a pulley or gear and that turn out fine from what I can see so anyone have any input on what may be causing my voids with that method. And I plan of casting using pipe since I got good results with that so far just to build up some stock.

So if anyone else here has been down this road any advise would be great not much to find on the net as to fixing problems just people say look what I did.

how well are you venting your molds? you must vent the **** out of the molds to let the steam and air out or you will end up with a lot of holes in the poured metal.

The molds are really just sand packed around different sizes of pipe in a stock pot I then pull the pipe out and pour the alum in the top. I removed the pipe and let the mold air dry while I melt the metal I also cast ever other one and let the heat dry out the sand even more as a test. I had about 10 in the stock pot. I know they use vents in molds and gates for flow which is to help with the air I think and shrinkage which may be my problem. But I did not have the problem just filling the pipes but I did have shrinkage but I just trim that off. I really thought a open mold some as large as 2 1/2 inch down to 1 inch would vent out while I was pouring.
But this is all new to me and I do not know the answer I am just guessing it was moisture in the sand could be how fast it was cooling trapping the air.

I have years of expereince casting different metals over the years. Al is one of the hardest ones to get clean void-free usable castings for.

Everything I turn and mill in my machine shops from Al is from aircraft grade hard aluminum from the local scrap yard. Having aircraft manufacturers and other manufacturing around the area, there is a vast selection of 1-6” barstock/rounds in any length I wish to buy (at very reasonable prices) and square/rectangual blocks also in any shape I need for projects.

Most industrial grade Al is vacuum cast so there are no voids or cavities in it. Also most is extrusion molded. Just pouring it into a hole in a cope & drag sand mold will yield very low quality porous castings. Been there. Done that many years ago in college and beyond. That method of rendering scrap is OK if your are sand casting ornamental and decorative shapes (or simple pullys), but not for accurate turned precision items.

Also many commercial items are rotationally molded to rid them of internal voids and cavities.

In other words.....buy your Al and brass turning stock from a reliable industrial supply house. Leave the home-brew castings to the back-woods artists casting trinkets for tourists.

Good luck!

Bangerjim

Well dang Jim rain on my parade that is not what I wanted to hear but was in the back of my mind. I searched around my area for anyone that would have some drops or scrap I could buy for my projects but no luck. That was my first path then I went online to find some to order a 2 inch dia 24 inchs was 45.00 and I am sure shipping would have it over 50 real quick. That is why I was playing with casting my own.
I am not ready to give up yet to much time invested and casting in pipe did give me a fair piece of stock that turned well. I am not making precision items with this material really learning how to and items that a small void would have not effect on how it works. I may just start casting fire ant nest and selling them on ebay to buy me some good stock lol.

I'd look into venting, trapped air needs somewhere to go, I think the better you vent, the fewer voids you will have.

I live in the Rust Belt and junk yards are full of stock for small projects you can buy cheap. I worked in a large Alumilum plant as a carbon setter. They don't know exactly what they have
until they draw a sample. A small mold is used to pour a sample billet. This is taken to lab and
shavings burnt in a spectrograph. The metal is then labeled when it's poured and the purchaser
must remelt and add whatever alloys required to bring the Alumilum to the specs needed for the
purpose. Guys would throw in pennies or a sledge hammer when they were mad at management.
This would produce a pot full that wouldn't bring the money that pure metal would. Melting odd
scrapp you don't know what you are going to end up with.

I have tinkered with doing exactly what you are trying. What I learned;
-Venting is important
- Use cast aluminum as your base material, engine blocks, kitchen machines, pots, etc anything that was cast originally will give better results than the random/extruded stuff.
-If you are getting tear out/problems with soft material, you need to lube the cut, an old timer told me to use lard, crisco seems to work ok
- the dull/ shiny pattern you are seeing is likely a harmonic vibration (causing chatter) set up in the piece.

Online Metal sis resonable for AL pieces most of the time. And check eBay! I have gotten a LOT of the AL tubing I use for antenna stuff from there!

it don't matter if you let the mold dry. i have worked with pottery and even letting the stuff dry for several days there is still moisture trapped in the structure of the clay. sand is no different. there is still molecular water content and that will create problems. the temperature required to get the molecular moisture out is around 600*F.. so letting it just sit there will not do it and you will still get steam and outgassing when the 1,400*F aluminum hits the sand. that is why it does not happen with the pipe but does with the sand, there is still moisture trapped in the molecular structure of the sand. must vent the mold to allow it to escape. but the open of the mold does not mean much. what will happen is that being the top is allowed to cool faster it will form a skin over the top while the bottom is still molten as the sand holds the heat in. while this is happening it plugs the mold off and allows steam and other gasses to be trapped in pockets in the aluminum.

I would suggest using REAL casting sand that does NOT involve any water at all! Black casting sand uses oil-based liquids to bond the sand. My local cast iron foundry had tons of it, so I could “borrow” a few dozen pounds!

Back when I was casting brass and aluminum on a regular basis, I could make up a cope & drag of black sand, and cast in it immediately because there was NO water involved. Black nasty stuff........but it really works. I have never used “green” sand. Takes too much time.

Water in any casting proceedure is just trouble looking for a place to happen!!!!!!!!

Commercial casters sure do not have the time to wait days and days for molds to dry out!!!!!!

Check it out!

Bangerjim

Helpful information people thanks for the replies you do not know somethings until you ask thanks.

One difficulty with alumin alloys is the oxide is the same weight as the metal,and so doesnt float on top of the melt......castings with oxide corrode quickly and break up....De oxidising and metal cleaning is normally done with fine bubbles of argon just before pour......as mention ,you need proper sandcast alloy,Al.10%Si,for a good easy casting.Even cast metal will not necessarily be right......When I was a kid,I worked with a neighbour who made good pulleys,esp cone pulleys with scrap ally from old motorbike crankcases,heads and gearboxes.......the bikes were old Indians and Harleys.,he especially like the WW2 Indian Chiefs....plenty of metal.

Brass is much easier to cast than ally,probably because mix isnt critical,and the poured metal is a lot heavier.In fact its pretty hard to get bad results with brass.......but heat is much higher,and just the heat from the crucible will singe your short and curlies right thru heavy clothes.....Always pour brass on a floor of loose sand,then it wont splash if something goes wrong.White heat takes a bit of getting used to..........finally,pure copper dont cast,you need some tin or zinc to make it work.

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Originally Posted by john.k

One difficulty with alumin alloys is the oxide is the same weight as the metal,and so doesnt float on top of the melt......castings with oxide corrode quickly and break up....De oxidising and metal cleaning is normally done with fine bubbles of argon just before pour......as mention ,you need proper sandcast alloy,Al.10%Si,for a good easy casting.Even cast metal will not necessarily be right......When I was a kid,I worked with a neighbour who made good pulleys,esp cone pulleys with scrap ally from old motorbike crankcases,heads and gearboxes.......the bikes were old Indians and Harleys.,he especially like the WW2 Indian Chiefs....plenty of metal.

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You and he would be interested in Burt Munro of New Zealand, one of whose records, set in 1967t the age of 68, still stands. He used to gravity-cast his own pistons etc. under the most primitive conditions, and his base machine was an Indian nowhere near as modern as WW2.

https://en.wikipedia.org/wiki/Burt_Munro

The trouble with aluminium for casting has two main sources. Some alloys aren't meant to be cast at all, and may respond badly to the process. Also they are too light, and gas bubbles don't rise as easily as they would with other metals.

While sand-casting often does involve a moisture content, this is something on which you should obtain concrete information, rather than proceed by the light of nature. Too much moisture can be dangerous, and not a little, but very. So-called sands are complex products, embodying a binding substance which is usually a type of clay.

https://en.wikipedia.org/wiki/Sand_casting#Green_sand

Brass or bronze are easier to work with, although they have higher melting-points. As to safety, you aren't in any more danger priming a bunker-buster bomb than a hand-grenade, but proper procedure will keep you safe. Some of the precolonial African bronzes are at least the technical equal of the best European renaissance work. You have to be pretty civilised to be a primitive.

casting metals is an art. i was involved in steel and bronze casting design for years, and can tell from your write-up that you need 2-5 years experience in a foundry shop and a much higher budget to get reliable product. not picking on you, as your efforts are great for an amateur, but metals casting of this nature is not lead casting simple. it is a complex art with significant expense.

Maybe this is getting over thought gave some background on what I was doing and how and for what reason.
I am not trying to get factory results just material that I can use to practice on and make something that it would not matter if it had a void.

From what I am getting is the green sand gives me lots of voids caused by venting moisture and gas, The pours I did in pipe did not have voids all over them or inside them just a few on the outside from what I have found so far.
The last thing was the alloy tearing instead of cutting which is coming from what I melted for the most part but still a unknown mix. The better material I start with the better I end with for the most part.

Looks like green sand is going to have that problem since its in it nature and metal molds will give me better results and last material is also key.
I have seen post that people suggested for alloy what was tearing to add about 10 to 15 percent brass.
I am not trying to cast works of art just some billet to feed my lathe.

Green sand at a low/correct moisture level will give good results with sufficient risers and vents......I suggest you get a beginners book on "hobby casting"..it will contain all the hints and tips you need for useful results.As to the naysayers,I have cast large bronze bearings out on site to repair an old crane,and for slipway winches ,that had to be kept going,using the exhaust from a diesel engine as a blower into a mound of dirt for a furnace.It aint rocket science,but it can be dangerous.

Watch this guys series, he does motor parts and stuff but the technique is what you are after.
https://www.youtube.com/user/myfordboy

Have you tried dry sand "lost foam" casting? Seems like it may work for turning stock.

All aluminum worth machining is going to be a wrought alloy.
Castings are mediocre even when produced by commercial foundries ran by PHD metallurgists.
For everyday machined components find a source for drop offs of 6061-T6 , T651 and T6511. These are all cold rolled, extruded or cold drawn rod, bar and plate. Don't waste anymore time on fire ant alloys.

6061-T6 is a cold worked alloy that has been heat treated. There is zero ways to produce an equivalent alloy at home. 6061-T6 is as strong as mild steel and will have no porosity.
You put 87 octane fuel in your car. 6061-T6 is the 87 octane equivalent in the world of aluminums fit for machining. There are many other alloys but none are remotely as popular as 6061-T6 in rod, bar or plate stock. It does not bend well so sheet metal is usually 5052-H32 or H34.
You can find plenty of references to back up what I say. I have been involved with machined parts for 50 years. That includes thousands of investment castings cast from A356 and millions of parts machined from 6061-T6.
So forget home cast alloys unless you enjoy wasting time.

It may seem illogical that what has been a good casting, won't make a good casting (or at least less easily than some others.) The answer is that so many modern aluminium castings are die-cast. i.e. squirted into the mould under pressure by equipment it is impractical for the amateur to have, like plastic.

Amateur heck I am a full blooded redneck and back woods get it done kind of fellow lol they say it cant be done will I got to see if for myself I have seen so many times that will not work or you can not do that just to find out well it can be done if you get lucky.
Thanks guys for all the input and know how you have shared with me. What is not good enough for some is great for others so to speak. Next time I fire up the smelter and do another pour may be what makes or breaks my plans on this project.
I am the guy that has to see for myself before I toss in the towel so no disrespect to anyone.

To turn ally,you need different type tooling to steel.......check a book,for rake and clearance angles,and also for a very sharp edge,honed with a fine wa****a stone.Inserts must be sharp edge positive rake for a hobby lathe,industrial negative rake inserts tear the surface at low speeds......incidentally,the finest finish on ally is produced with a diamond tool.Not as costly as you might think.

The censor just bleeped a well known type of natural abrasive stone.....

I do not know what kind of stone that would be PM me the word put spaces between the letters so the filter will not block it and I will let Robert adjust the filter if he is able.
Any word you type that is filter do not try to bypass the word that is a infraction btw just type it out it will get blocked if needed.

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Originally Posted by RP

Amateur heck I am a full blooded redneck and back woods get it done kind of fellow lol.

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They pay a living wage for that? Seriously, as long as gunsmithing and other technology is carried out successfully, or even to an understandable level of unsuccessfully, I admire the craftsman all the more for doing it in an amateur capacity. A bit like the more controversial forms of interpersonal relations, really.

Ah, the Wash-it-a stone!

Wa****a

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Originally Posted by Ballistics in Scotland

They pay a living wage for that? Seriously, as long as gunsmithing and other technology is carried out successfully, or even to an understandable level of unsuccessfully, I admire the craftsman all the more for doing it in an amateur capacity. A bit like the more controversial forms of interpersonal relations, really.

Ah, the Wash-it-a stone!

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Man those are a lot of big words as far as living wage not sure, I am not a gunsmith but I do own some tools they say are for a gunsmith so maybe I am. Not sure what your trying to say but I have to give you a A for the attempt at humor keep trying and you may not come off as insulting.
If you look at the OP the ? was on smelting alm copper and brass for tips or advice on what works and what to look out for. But as always threads go left and right but information is shared most of the time. There is the comments that add nothing to the thread but some people just have to make a comment I guess that is why facebook has so many people on it. I understand most people do not get my humor either.

Ill settle for a fine arkansas stone ,so s as not to offend anyone.

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Originally Posted by RP

Man those are a lot of big words as far as living wage not sure, I am not a gunsmith but I do own some tools they say are for a gunsmith so maybe I am. Not sure what your trying to say but I have to give you a A for the attempt at humor keep trying and you may not come off as insulting. .

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I believe most people would have seen that no insult was intended, and I certainly wouldn't criticise anyone who chose to keep trying as you suggest.

Our die cast dies the aluminum alloys were shot into the moulds with a shot tube and produced a pressurized shot that filled out much better. When we poured in to a can for stock to use it was always gummy and nasty to work with. But the parts cast under pressures turned milled and tapped fine. the pressure casts gave a better grain structure in the material.

One thing you might try on you sand casts is a longer larger feed and puddle into the mould this will help add some slight pressure to the materials and help push air out.

For awhile I helped an old pattern maker pour the parts for freeland style scope stands. He used aluminum cans for stock. fluxed heavy ( Borax I think) and his inlets were large and 4-6" long. He got good castings almost every time. He would make a run of stands every spring and fall for club members.

Pure aluminium will pick up silicon from sand,and cans could probably be made to cast a lot easier by experimenting with sand flour,which is available for making investment molds.Ive never tried,because I had large stocks of scrap crankcases and sumps from big old diesel engines.....some old engines even had magnesium crankcases and sumps post WW2,when the metal was widely available as scrap...VWs pre about 1957 is a well known one....Magnesium casts and welds very easily,but catches fire easily too,and all you are left with is white powder.

Some of which was your moustache. Country gent's experience, die-castings from metal moulds being easier to work than pieces cast in the open, suggests that the latter may have solidified more slowly, and allowed larger-scale crystallisation of whatever wasn't sluminium.

both magnesium and zinc ignite and burn quietly,spectacular,but not dangerous ,in my experience.....When casting brass,overheating can ignite the zinc,but with the availability of cheap thermocouples there should be no problem

I been working on some pipe molds made out of exhaust pipe, I cut down the weld seam then cleaned up the cut. I am going to place them in a angle iron base set at a angle and use some clamps to hold the pipe cut together. Thinking of welding a plate on the angle to act as a dam and let the clamps also hold the mold to keep the alum from running out the end.
My thinking behind this was the results I got using the pipe were good so bypassing the sand for now. Also set at a angle may help with the air pockets or voids since the alloy will be flowing in at a angle not stg down pushing air in. I have several pipes cut and thinking two bases so I can pour two let them cool while melting more alloy.
I turned the first alloy I cast in the pipe more and only found one more void which I think is good I cut from the outside and even bored and drilled some looking at the inside. That was in one of them the other was clear on the inside had two voids on the outside.
I also have more books coming for making items on a lathe kind of how to books so I will have more stuff to practice on before trying to make something that needs to be on the money.
Also I seen mix reviews on the fluxing and degassing I think it depends on what your end product is going to be right now that is my line of thinking.
Again thanks for all the advice and suggestions.

As to fluxing, I have done quite a bit of soldering in sterling silver, and didn't find pure borax worked as well as such products as the Johnson Matthey Tenacity solders. For fluxing metals which melt at higher temperatures, you would probably be best with one of these:

http://www.jm-metaljoining.com/products/tenacity

I don't know if those specific products are easily available on the US market, although they claim to be world-wide. But there are surely similar products available.

I aluminum investment castings I have machined were cast with A356 356.2 aluminum.

Some of them have had a lot of inclusions in them, able to “fix” some by filling with a TIG welder. These were not things that were structural but things like blade guards (to keep hands out), dust shoots, name plates and such.

If you are just wanting cheap material to practice machining, get some plastic. Will machine better and be easier on tooling.

I have used plastic and it cuts like a dream not bad material to play with for a learning tool.
Well it was a struggle today one problem after another the split pipe was a fail. So far smooth wall pipe ( no welded seam) been working the best for me. I just need to find some more different dia it looks like.
The pipe is open on both ends and I set it on a large I beam I use to hold a vise and fill it up as it cools which is kind of fast and sucks in I slowly add more alloy since the top is still fairly hot. Have not noticed any bad effect do this and then I drop them in some water,
When they cool off enough the alloy will slid out the end with a tap or two. The pipe is thick wall so it holds the heat well and by the time I dip out more alloy there is no sign of water.
I need to make some more mods on the smelter itself had a hard time get it up to temp so most of my day was in vain aggg. Did get some blanks that look good at the end.
I also noticed the longer the blanks sit or age the better they seem to turn or maybe that is just in my mind wishing things into facts lol.