Clay molds for aluminum casting?

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GLBowers
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Brass Casting with sand mixture

Postby GLBowers » Sat Sep 09, 2017 12:04 am

Photo of the other side (original on right).
I'm not totally satisfied with my results, but it's good enough for me to use - however, I think I can get more mold detail with the next pour (now that I have an idea of what to do). THANK YOU FOR THE HELP AND GUIDANCE - I'll share more with you as I learn, if that won't be a problem for youall.
Thanks,
Garman
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Harold_V
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Re: Clay molds for aluminum casting?

Postby Harold_V » Sat Sep 09, 2017 1:49 am

I have no experience with casting copper alloys, aside from casting some copper ingots, so my input isn't likely to be useful. Good to see you're achieving results, though, and I expect that you'll be able to improve the quality. Looks like detail is suffering a little, but experience should help. Everything I've read in regards to casting dictates that copper alloys are more difficult to cast than other alloys.

H
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steamin10
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Re: Clay molds for aluminum casting?

Postby steamin10 » Sun Sep 10, 2017 1:25 am

Looking at the pix, I have the feeling your pattern is a bit rough, and that is reflected in the end product. 'sand casting has its own texture that will overlay the original shape.

I would be happy with the results shown, especially for a first try. The next step is to refine the pattern to get more smoothness, and of course to gang the pattern for multiples.

Patterns can be hand made from epoxy tube type mix, the original pressed in modeling clay, and cleaned up a bit after. coating with shellac or some brush on lacquer, and smoothed with files and steel wool can fill and level out the surface of new patterns to slick them out. Generally your part will be slightly less than the original pattern, so that a copy of copy fades in detail. Commercial modeling wax is easy to work with small hand tools, and your imagination will be its only limits for shields, eagles or any other surface designs and art you wish to carve. It has the advantage that any tool warmed in a candlle flame can move the wax for shaping your design or carved cold with x-acto blades and dental tools.

Any copper alloy is prone to gassy holes and oxides. You seem to have missed that problem this round. Heat fast, pour quick, and dont hold metal. Good show.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

GLBowers
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Re: Clay molds for aluminum casting?

Postby GLBowers » Sun Sep 10, 2017 8:31 pm

Steamin10,

you are correct on the pattern, however, the pattern is part of an original 1800's snare strainer that may have been casted by a sand mold back then which would account for how it looks. I didn't want the casting to look any better nor worse than the original 1800's Brass Piece - AND with you help and guidance I reached my goal, Thanks! I do plan on making a mold with two of the brass top pieces (maybe three, if I can) for this week's lesson in casting.

I casted an original Nickel Silver key for an 1860's nickel silver tuba today and it also turned out great - I was a little worried that the nickel silver might not be as easy to cast as the brass but other than having to melt it at a higher temperature, it was like working with the brass. If you like I will keep sharing my endeavors with you, but if not, that's OK.
Thanks again,
Garman

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steamin10
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Re: Clay molds for aluminum casting?

Postby steamin10 » Tue Sep 12, 2017 1:34 am

Casting silver alloys are another bug to conquer, as they oxidize quickly and can get gassy. Ask any active Jeweler or those that work in south western silver trinkets.

In all things, perfection is rarely achieved, but always the goal. Such items as your keys were made quickly, and fulfilled a function. My critique is one of support, and encouragement, not actual criticism. You are successful, because you followed the road and did not give up. You solved many problems along the way, including supply of sand, and molding. Most that bear witness, will have that "WOW" moment, when you reveal that you made the keys, in the spirit of old. For me, that is reward enough, not to mention that vicariously I can live in the zone of "I helped" at least in spirit. Kudos to you for your follow through.

By the way, do not fret too much about the color shift of the sand from brown to black. The burning of the oil and carbonizing of the alky out of the mix is responsible for this, and when the sand begins to lose co-hessian for molding, just a touch of alky and sometimes an oz of oil will regenerate the sand to a mold able state.
Care must be taken that you dont overdue the chemical additions. Foundries have the problem of the sand actually breaking down over time from the heat breaking the grains into finer pieces, and trash, dust, dirt and particularly sawdust effecting the mix. Sawdust and wooden or cardboard boxes will eventually soak the oil out of the sand, and it will lose the desired sticky quality. The aalky is the first thing that should be considered to restore long standing sand, and mulling the next, to eliminate dry spots.

I am always interested in the what and how people accomplish what they do. There is no right or wrong of it, just better results, and safer actions. After all, burns, cuts and metal slivers are the norm for these somewhat risky activities, and many normal people shy away from such risks. For me, I have the Edison complex. When told he had failed to make a working light bulb in 1100 tries, Thomas Alva disagreed, and quipped he now knew 1100 ways how NOT to make a bulb. To this day we still know such bulbs as an Edison base, by one of the other innovations he worked out. So,was the first working bulb perfect: not by a long shot. We look at such genius as quaint now. But I think you get my point.
Big Dave, former Millwright, Electrician, Environmental conditioning, and back yard Fixxit guy. Now retired, persuing boats, trains, and broken relics.
We have enough youth, how about a fountain of Smart. My computer beat me at chess, but not kickboxing
It is not getting caught in the rain, its learning to dance in it. People saying good morning, should have to prove it.

GLBowers
Posts: 18
Joined: Sat Sep 02, 2017 5:16 pm

Brass casting with sand mixture

Postby GLBowers » Thu Sep 14, 2017 11:19 am

Thanks Steamin10,
Garman

GLBowers
Posts: 18
Joined: Sat Sep 02, 2017 5:16 pm

Brass casting with sand mixture

Postby GLBowers » Thu Sep 14, 2017 5:07 pm

Steam10,

Please forgive me, but I'm a total novice, if you use slang terms it really messes with my head. What is "alky"? I looked it up to find that when the sand mixture needs refreshed you are telling me to add some Alcoholics? :) SOOooo... I'm having to ask you exactly how do I add Alcoholics - cut them up or just roll them in it???? ;/ :( :) (I tried to use smiley faces but this site doesn't recognize them)
Help,
Garman

GLBowers
Posts: 18
Joined: Sat Sep 02, 2017 5:16 pm

Re: Clay molds for aluminum casting?

Postby GLBowers » Thu Sep 14, 2017 5:08 pm

Oh! It did, sorry.


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