Tooling alloy question

[Eagle66]

I’ve been thinking about making some of my own gerb/rocket tools. My lathe doesn’t have a lot of capacity or fancy tooling, but if I do my part, it gets the job done. Instead of buying Al bar stock to turn, given that I have a couple hundred pounds of Al ingots, I figured I would cast my own bar stock. I can cast plain bar and cut away everything that doesn’t look like the tool I want, just like I would if I bought bar stock, or I could cast a piece that is roughly the shape of the tool I want and turn that to the finished specs. Either way, all the chips go back into the pot for reuse..

 

My question has to do with which alloy to use. I have two kinds. One is essentially 6061, pure Al. The other is high quality casting alloy from castings like pistons, cylinder heads, and such. Which would be best for the tooling?

[mikeee]

If you are going to go to the trouble of casting the metal why not make some Magnelium and make a few dollars and

then buy the aluminum bar stock. There are several videos that show the process of making the Magnelium which is

very easy to do with proper safety precautions. Several members made some at our last club pyro shoot and it

turned out to be an easy process to make the material with coals as the heat source. All you need is some magnesium

to mix in with the aluminum when you melt it in a covered container.

[marks265]

T6061 alloy is usually a good grade and acceptable for many things that would work for what we do.

[Arthur]

A soft alloy will change shape as you hit it to ram pyro, a harder alloy will take that better.

[Eagle66]

If you are going to go to the trouble of casting the metal why not make some Magnelium and make a few dollars and

then buy the aluminum bar stock. ... All you need is some magnesium to mix in with the aluminum when you melt it in a covered container.

 

Since I have both Mg & Al, MgAl is definitely on the agenda when I fire up my foundry furnace. I'm also going to purify some scrap and cast a few things including bar stock. Why cast bar stock? Because I can & it's free except for the propane, and if I burn waste oil, it's all free.

 

I know I'm hijacking my own thread, but for me, this is part of the game. I cast & machine metal because it's more rewarding than buying it. Why make fireworks instead of buying? Same reason. (However, my wife says I just like to set things on fire. She's probably right.) Woodworking, fabricating tools, casting my own bullets, etc., it's all the same. Having fun doing is reason enough, even if I don't save $$.

Edited November 22, 2014 by Eagle66

[dagabu]

That sounds like a lot of fun to do Eagle, just watch your dross when you pour the mold. Al is really susceptible to air bubbles (I bet you know that already) and that can ruin your tooling.

 

The 6061 T-6 is alloyed with magnesium and silicon, is solution heat treated and artificially aged. Once melted and the heat treating drawn off, it will cast significantly softer and will mushroom and deform under pressure.

 

Cast alloys are even more interesting to play with and if you use a few different castings in the same pot, you can end up with brittle or soft castings, even though the host metals are hard and durable by themselves. The best advice I can give you is to find a single source of donor metal, check it for durability, strike it with a centerpoint and compare the strike mark to a known hardness (like a section of 6061 , 2024 or 7075) and see which gives you the hardness you are looking for. Then cast only that donor metal, dont mix them!

 

If you are lucky, you will find an ANSI stamp on some castings, like ANSI 201.0, it's not required but depending on the specifications that the part manufacturer had to follow, they may have cast the material number in the part. Keep in mind that many cast parts are also heat treated to a T rating while the 4XX.X and 5XX.X are normally not heat treated.

Good luck with your project!

[Eagle66]

Wow. One of the great things about this forum is that if you ask a question, the answers you get may be more informative than you ever expected. When it comes to casting Al, I've always taken a rather simplistic approach. On one hand I have essentially pure Al, from scrap like window screen frames, lawn chair tubes, soda cans, etc. It's very good for applications where strength, mechinability, etc., are not really critical. On the other hand, there is what I have called "good casting alloy", from scrap like pistons, engine blocks, wheels, Al mower decks, etc smelted into a hobo's stew of metal that meets my needs for applications where strength, etc are important.

 

Then there are the materials such as Dagabu describes, for applications where strength, hardness, durability, and consistency are critical. I've never gone there before, but now, thanks to Dag, I have another another avenue to explore for my other hobby. The learning never stops until you do. Thank you.

 

Oh, and I got the answer to my question, too. I'll try making some tooling from my good stuff and see what happens. Worst case, I'll learn something I didn't know before.

 

Or maybe I can trade some MgAl for some 6061 T6.

[MrB]

Or maybe I can trade some MgAl for some 6061 T6.

Not sure about the trading bit, but a fair guess is that "cheap" MgAl will move well enough to make you able to buy the 6061. I'd aim for "scrap" premium bike frames. Bicycles that is. It should be fairly easy to find out if the frame is, or isn't 6061 T6, cutting it to size, and melting it should be really easy. Casting... not so sure. That might be why one wants to buy it as rods. In that case... Nevermind ;- )

B!

[dagabu]

Not sure about the trading bit, but a fair guess is that "cheap" MgAl will move well enough to make you able to buy the 6061. I'd aim for "scrap" premium bike frames. Bicycles that is. It should be fairly easy to find out if the frame is, or isn't 6061 T6, cutting it to size, and melting it should be really easy. Casting... not so sure. That might be why one wants to buy it as rods. In that case... Nevermind ;- )

B!

 

Bicycle frames have been made from all sorts of aluminum alloys, in the 80's, it was almost pure aluminum and today it is custom DOM with thin centers and thick butts so you can weld it. Once welded, they are heat treated to give it stiffness, 7XXX and 6XXX series of alloys are used for different frames, 6XXX is used where a lot of give is wanted, 7XXX is used where stiffness is desired.

 

The real challenge with these materials is the paint and stickers ect, they really foul the melt and create a lot of dross.

[dagabu]

Wow. One of the great things about this forum is that if you ask a question, the answers you get may be more informative than you ever expected. When it comes to casting Al, I've always taken a rather simplistic approach. On one hand I have essentially pure Al, from scrap like window screen frames, lawn chair tubes, soda cans, etc. It's very good for applications where strength, mechinability, etc., are not really critical. On the other hand, there is what I have called "good casting alloy", from scrap like pistons, engine blocks, wheels, Al mower decks, etc smelted into a hobo's stew of metal that meets my needs for applications where strength, etc are important.

 

Then there are the materials such as Dagabu describes, for applications where strength, hardness, durability, and consistency are critical. I've never gone there before, but now, thanks to Dag, I have another another avenue to explore for my other hobby. The learning never stops until you do. Thank you.

 

Oh, and I got the answer to my question, too. I'll try making some tooling from my good stuff and see what happens. Worst case, I'll learn something I didn't know before.

 

Or maybe I can trade some MgAl for some 6061 T6.

 

I would be happy to trade you MgAl for new US made 6061 T-6, PM me and we can work out the details. I have brass as well, once you see what the difference is with spindles, I bet you will be using brass for all your high wear surfaces.

 

Remember, porosity WILL happen without the right process, aluminum LOVES to make air pockets and isn't cast into rods like bases and wheel hubs, it is pressures fed and shielded then rolled, pounded etc to make the shape.

[MrB]

 

Bicycle frames have been made from all sorts of aluminum alloys,

Thats why i suggested premium frames. It makes it real easy to check what the frame was actually made of. Your entirely right tho.

B!

[dagabu]

Thats why i suggested premium frames. It makes it real easy to check what the frame was actually made of. Your entirely right tho.

B!

 

Premium or not, it's off the shelf base materials, there is no ultra-special aluminum alloy use on high end bicycles though some of it is claimed to be but that's just because they add 0.001% Copper or another unimportant metal to make a patentable alloy. It's no stronger or better once you melt it down and anneal it.

 

"There's nothing new under the sun."

-Solomon-

[MrB]

 

Premium or not, it's off the shelf base materials, there is no ultra-special aluminum alloy use on high end bicycles

No of course it's not. He wanted 6061 T6. Which is widely used in alu bike frames. Buying a premium bike means you can very easily verify what was used. And, since he's buying scrap premium bikes, he's not paying a premium, but scrap prices. I'm not sure, but i think we are, or have been, talking past one and other. I'm just feeling confused. Of course there is nothing "special" in bike frames. That was the whole point.

[dagabu]

No of course it's not. He wanted 6061 T6. Which is widely used in alu bike frames. Buying a premium bike means you can very easily verify what was used. And, since he's buying scrap premium bikes, he's not paying a premium, but scrap prices. I'm not sure, but i think we are, or have been, talking past one and other. I'm just feeling confused. Of course there is nothing "special" in bike frames. That was the whole point.

 

GOTCHA!!!! Yes, we were indeed saying the very same thing, sorry about that B!

 

Our local SCHWINN dealer throws all the frames away in the dumpster now that the local recycler demands "clean metals" only.

Edited November 24, 2014 by dagabu

[MrB]

 

GOTCHA!!!! Yes, we were indeed saying the very same thing, sorry about that B!

Goody. Thats the Internet for ya, i can live with that.

 

Our local SCHWINN dealer throws all the frames away in the dumpster now that the local recycler demands "clean metals" only.

Since it's alot about powdercoating when it comes to bike frames... Burning them wont help a whole lot. For your home melting purposes it should just end up being a lot of crud on top of the melt, and if thats to be avoided the frames need to be stripped mechanically, i'm thinking sandblasting. Probably not worth the extra hassle. Anyway, i'm not sure about Schwinn. It's a great name to retro bikers around here, but i don't think i've ever seen a modern premium type "race" bike, be it on or off road. It makes me think they are just not that present in Europe? Anyway, i was thinking more along the lines of brands i'm more familiar with, Cannondale and their "Optimized 6061 Alloy", (It's one of those unobtanium products Dagabu was referring to, with 0.001% added something, just to make it their own flavor without changing the properties.) or Bianchi and pure and simple "6061" alloy. Hell, even handlebars are made from the right stuff, and is individually listed most the time.

However, if the list states just "alloy" then it's not a 6061 bit of kit.

 

But your local recycler just proves one thing. Metals are to cheap. If the aluminum was worth a damn, they'd melt it, and remove the crud. Leaves opportunity for the home forger, i suppose. Just ask first, and the bike shop of choice probably will just go "sure, have at it". They might even be willing to put the frames aside for someone who asks, but they will make sure the bottom bracket / steering hub is toast, just to prevent it from re-entering the market as a bike. Or well, again, thats my experience from around here. YMMV, i think it's...

B!

[dagabu]

Yes, they are happy to give them away and even help you load it in your car. They know you will be back...

[Zingy]

For an initial research reference, castings and machining of metal castings, is referred to as: "Patternmaking". In using a search engine, use 'patternmaking-castings', so you do not come up with clothing design.

Edited December 16, 2014 by Zingy

[marks265]

For an initial research reference, castings and machining of metal castings, is referred to as: "Patternmaking". In using a search engine, use 'patternmaking-castings', so you do not come up with clothing design.

You would want to search sand castings. Pattern makers make the forms that the sand is packed into. The pattern is removed, metal is poured in then when cooled, the sand and the casting go through a shaker or other means to separate the two. This is the very short version of course.