Gundog48 Posted February 6, 2013 Share Posted February 6, 2013 I'm working on a school project and to start I need a fairly long(~12") aluminium rod that is just over 3" in diameter. Now, if I bought that from a metal merchant, I'd be broke. So we plan to cast a rod using the facilities at school. The only problem is that the only one qualified to help is ill and will be away until after the finished product needs to be in, so I need an alternative.The rod doesn't have to be perfect as it'll be turned on a lathe, as long as it is roughly round and not too small. The issue is going to be the size of the casting, it's pretty huge. I've seen 'ingots' being cast from scrap ali at school where they just pour it into a piece of angle iron, so here is what I was wondering:- If I got some 80mm steel pipe with a good wall thickness, could I use that as an open mold for casting rather than using sand?- Would the pipe need to be preheated in any way, and how should the end be capped?- What would you recommend I use as a crucible, are there any good alternatives to the proper ceramic ones for a one-off?- If I had to do the cast in multiple pours, would the second pour have enough heat to melt some of the ali in the mold from the first pour and 'weld' them together, or am I limited to the size of my crucible?Thanks! Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted February 6, 2013 Share Posted February 6, 2013 Plan b is in order here,,you do not seem ready for this project nor do you have or understand the equipment and protective equipment needed. i buy aluminum scrap from a local recycling metals dealer. I pay by the pound and the price hinges on the market price and wotever they wish to add to that. i have all of the equpiment and personal protection to do aluminum castings I have done smaller ones. I wouid have to figure out the volume of aluminum needed and see if the crucible I have is large enough to pour in one, if not I could not do it as the time to heat and melt another would make the pour fail. Also the aluminum to melt would not come free. You can research to find out why you would not want to try this with aluminum drink cans. I am not volunteering to do this pour, just pointing out a few things you need to see. you may even want to consider replacing this project with one that is doable considering wot you have to work with. Quote Link to comment Share on other sites More sharing options...
Gundog48 Posted February 6, 2013 Author Share Posted February 6, 2013 Thanks for the tip, I've certainly been considering it. I was hoping to get a loan of the protective gear from the school, they've got a really well kitted out forge/foundry that barely gets any use. I can get small amounts of scrap aluminium for free, or get it from a scrapyard cheaply enough. The reason I am so hesitant is because it would cost me around £40 per foot.But you're right, I have no knowledge of casting apart from what I've seen/read, seeing as I can't get any help with this, I will have to look at the alternatives. I was hoping that I could create a casting over multiple pours and that it would become hot enough to fuse with the existing metal, but this is not the case.I'd like to learn more about it and give it a try though, I may try some brass casting some time with much smaller pours, and perhaps get a proper gas furnace.It's a little frustrating having to shell out so much when all I need is something long enough, wide enough and roughly round! Quote Link to comment Share on other sites More sharing options...
Robert Yates Posted February 6, 2013 Share Posted February 6, 2013 Firs of I agree with Rich, second you are wrong in so many ways as to working with aluminum ! it WILL Hurt you fast and bad fumes, heat,and the molten metal,as well as having a very poor casting that you intend on turning on a lathe it has the potential to fly apart or explode in your face or chest . Welding them together is an epic failure at that size if you have no idea what you are doing and you will create a difference of materials when doing so thus another lathe issue. Sorry Brother you Need to back up and punt again with the Teachers Approval and an out line of your Experiment of just what you intend to do . Sam IMHO Quote Link to comment Share on other sites More sharing options...
Gundog48 Posted February 6, 2013 Author Share Posted February 6, 2013 Thanks for the advice, that's what I need. I'll scrap this idea and look for an alternative. I don't know enough about aluminium, or anything other than steel really. I'll stick to my plans of having a go at some brass knife fittings or crossguards at home and only do heavy casting at school under supervision. Quote Link to comment Share on other sites More sharing options...
Dave Budd Posted February 6, 2013 Share Posted February 6, 2013 Is there an alternative to the 3" aluminium? I wonder if you could use a different material to do the same job, such as nylon (available in 3" round and much cheaper than ally) or maybe assemble a plywood billet that can be turned down. Quote Link to comment Share on other sites More sharing options...
Gundog48 Posted February 13, 2013 Author Share Posted February 13, 2013 Wasn't really an alternative, really needed the aluminium finish! Managed to get it done at school though, it was a very big pour but we just about managed it! Quote Link to comment Share on other sites More sharing options...
Robert Yates Posted February 13, 2013 Share Posted February 13, 2013 Good to Here you did get it done Now Post some Photos . Sam Quote Link to comment Share on other sites More sharing options...
Gundog48 Posted February 14, 2013 Author Share Posted February 14, 2013 Here you go! We were really pushing it in terms of volume with a full crucible, it wasn't quite enough as a pass on the lathe revealed a low spot- not to worry, it'll only reduce the diameter by a few mm. The surface is about as good as you could expect from simple gravity casting! Very excited to work with liquid metal for the first time! Quote Link to comment Share on other sites More sharing options...
Robert Yates Posted February 15, 2013 Share Posted February 15, 2013 Well Done Looks good for a first pour 7 done safely Quote Link to comment Share on other sites More sharing options...
JNewman Posted February 15, 2013 Share Posted February 15, 2013 Looks good. The low spot you have there is a shrink. You may have an internal void as well. You could have prevented it with a riser except it sounds like you didn't have a big enough crucible and you would have had trouble fitting it in that flask unless you just stuck it on the top. Quote Link to comment Share on other sites More sharing options...
LeeMcKee Posted February 17, 2013 Share Posted February 17, 2013 You could add a pour cup to the mould as it would increase you hyperstatic flow pressure as well as acting as a riser for shrinkage. you could also cut blind risers into the mould off to the side and cut them off before turning on the lathe. Not bad for your first casting.... If you need a bigger crucible you can weld one up out of steel as the 1300 degree heat will not phase it. Quote Link to comment Share on other sites More sharing options...
H&T Posted February 20, 2013 Share Posted February 20, 2013 well done Gundog48. I commend you for your use of English, your enthusiasm and the articulate way in which you askedyour question and described the results of your efforts. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted February 21, 2013 Share Posted February 21, 2013 How did you degass the melt? Quote Link to comment Share on other sites More sharing options...
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