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Casting bar stock?
Posted: Wed Mar 25, 2015 7:36 pm
Hi there, new user here first post
I am generally speaking a home taught novice in metalworking and acquired my first metalwork lathe last year which has been all sorts of fun. But I have now come up with the plan of turning my collection of brass/copper/aluminium scrap into usuable items, and it would be especially handy if I can cast up some bar stock in various diametres.
I have made an excellent and powerful propane torch which I am sure will melt any of the above mentioned metals in decent batches, it roars quite loud with a 1.5 foot long blue flame. I am yet to construct an actual furnace but I'm getting there.
So I was wondering what would be the best way to go about pouring simple cylindrical 'bar stock' for use in lathe work? What kinds of moulds and techniques have people used for this? I understand that commercial bar stock is likely to be extruded not cast, but for my purposes it wont matter so long as the resultant metal isnt porous or full of defects.
Looking forward to your thoughts!
Re: Casting bar stock?
Posted: Wed Mar 25, 2015 10:35 pm
Welcome to the board, and please put an approximate location in your header. it helps to know you better, as you may have neighbors that can help within travel distance. It makes everyone closer and more willing to help.
You ask a simple question, that has a complex answer. If you are going to do scrap casting, beware that all is not what it seems. "plumbing brass' is not the same as a graded bar stock, so melting all the tubes,valves and corroded toilet junk, may not give you a good cast, and will generally be leaded, as it is added to the production castings for good machining. Also understand, that brass, red brass, and bearing bronze, are not the same by a long shot.there are more than 50 common copper alloyed bronzes in current use, so scrap ID is iffy at best. (bronze is any copper alloy, brass, being copper zinc alloy. What is considered bronze for gunmetal, bells, and marine, is generally without zinc, and alloyed with Tin.)
Having said that, I have remelted turnings and bits and cast bars of various shapes to use in my projects. Better than turning them in as scrap, but a bother to get it done, unless you are casting parts anyway. Gasyness and pinholes are a trouble with slow melting, and poor flux. It can be dealt with.
A furnace need not be fancy, just a lot of heat input that swirls off the walls, and does not blow on the centered vessel. It can be built in a 6 gallon tin bucket, with a riel type burner for little money. I recommend you read a bit, many hobby books about art casting, and the like. Some good stuff on u-tube, if you add a grain of salt, to the 'experts' that post there.
You stand in the doorway to an immense learning curve, if you take the step. Know that the chinese have been doing bronze castings for about 2k years, so it can be done easily enough in modern times. But it will take patience, and details of knowledge to get good. I hold the stream on this board by Pipsecs, AKA Charlie Pipes as a good tutelage for home casting. There is a search feature, that will allow you to scan the threads for information. A bit of reading will set you way down the right road without making all the mistakes on your own. This is done with home available tooling, so there is no need to re-invent the wheel. Just follow the footsteps that are plain, and you will be well along on your journey. Have fun.
Re: Casting bar stock?
Posted: Mon Aug 01, 2016 12:11 pm
I've made quite a lot of bar stock (aluminium, brass fittings, copper wire...). Get your mold hot enough so the metal doesn't freeze while pouring. Also, the more liquid the metal, the easier inclusions will float, thus not contaminate the cast.
Use at least 5mm thick metal pipe walls.
Make sure the pipe is clean an nothing can prevent the cast from getting out of the mold.
If melting alumimium, don't stirr too much, don't get it too hot, run rich so you have a minimum of O2 in the furnace, try first without degassers and fluxes. They tend to mess up the cast if used incorrectly/excessively.
Don't get overwhelmed by the gazillion of alloys that exist. Just start with what you have laying around, the rest will come gradually.
Re: Casting bar stock?
Posted: Tue Oct 04, 2016 2:53 pm
I dont know how I missed this, I usually watch this column more than lately.
I rebut the idea of a pipe crucible. Especially aluminum will dissolve the steel (iron) and you will lose flow and other desirable characteristics we like from aluminum. For casting anything more than a couple of pounds, invest in crucibles and get better product right off the bat.
Again, read, read, read. and watch all the boring U-tube junk out there, there are nuggets of information that can work for you, even if some parts are wrong. CW Ammen put out a handful of books useful to the Home Casting guy, and I recommend them as a start for your library.