ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Alan,

Amazing work! Congratulations on your sucess. I assume that the lovely Missus B is happy you are done mucking up her kitchen.

A inexpensive source for vacuum pumps would be recycled refrigeration compressors and air compressors.

Larry C

Mighty impressive! Alan, what was your method of melting that down it appears to be a cast iron stove?

Alan, Nice, actually great job.

Thanks for posting the results.

Bravo Alan

..how many can you cast with those molds?

Alan, is the tractor gas or diesel? I am a member of two diesel forums and some of the members have done their own badges as well. Even though the forums are for Mercedes diesels and Navistar diesels, many of the members are diesel addicts and own tractors as well.

Thanks all for your kind comments, much appreciated.

LarryC, a] The lovely Missus B [ I can’t tell you how pleased she was to read that, thankyou ] was out all day Sunday helping run a stall raising money for the ‘old and unwanted doggies’ Home at an exhibition. Cat's away, mice.....b] She has a new kitchen nearly ready at the other end of the house - this one is due for the dumpster next spring- so she only went half-ape. & c] I cleaned up most of the mess, but you never quite get rid of all the evidence, do you? As long as you don’t spill tin alloy on anything porous or organic, this is a very clean operation and the temperature is not much more than for toffee or caramelised sugar. I’m told [www.] that some of the lower m.p. alloys containing bismuth stink awfully, and of course lead-alloys are a no-no in the kitchen.
I have an old compressor somewhere in the queue for renovation- I might turn it into a vac pump.

Mark; It’s a quartz-halogen hob. The top is black glass of some sort, with 4 ‘lamps’ under and it just wipes clean, even after 6 years of spills of everything- burned milk, meat juices, sugar, etc.. It has thermostatic controls, [ lovely for melting metals! ] but a slow response. Gets ruddy hot though, over 600°F. BTW my stainless ladle was $1.50 in the supermart.

Togol, Other users on the www state 25-40 castings from a mould before imperfections begin to occur, this is after all rubber.
The life depends a lot on how hot the metal is, and how detailed the casting needs to be to be acceptable. I spin-cast six plaques and they all look identical. Once a charge has all melted in the pot, [ and thus the braking action of the latent heat of fusion of the un-melted portion is lost], the temperature rockets up fast! If you guess, you’re in trouble IMO - many users complain of ‘gassing’, a sure sign of burning the RTV; my IR thermometer only cost $30, and is a boon to an old fuss-pot like me, wandering round the supermarket checking out the temperatures of the chiller cabinets & checkout staff; [ "This one's still alive, dear!" ]
Rhodia’s technical department reckon it will take a few shots of pure lead at over 620°F
The dusting of the mold in talc or graphite prolongs life too, by reducing scouring and direct contact.
I also bought a little electronic balance [ increments 0.03 oz ] to measure the catalyst, as getting the right RTV mix is also vital, and I wanted quite a few batches.

Big B. It's a direct-injection diesel engine, naturally aspirated, 6 speed box + 1 reverse.
Renault fitted the unbreakable [British!] water-cooled Perkins 3-cylinder engine, the type P3 TA/4924 in this model, 2.365 liter, 30hp at 1700rpm. There was also a choice of 16hp gasoline [ mainly for vinyards ], plus 22hp or 35hp models with air-cooled MWM 3-cylinder diesels.
They built around 13,500 of the 30hp variant between 1956-60. Very few got exported.

Alan


[This message has been edited by Alan Belson (edited 11-11-2006).]

Alan, I enjoy seeing your excellent work,it takes me back since it's been > 36 years when I was in H.S. foundry class.
where I poured Aluminum, Brass, and Iron in silica sand.

I was in the class for three years, and I managed to make a lot of stuff, but sadly
all of it, my plaques, pots and pans, bookends, pier joints, hurricane lamps, door knockers, peace symbols, weather vanes, house signs, crucifix....are all gone.....


Why three years??....well,..... it was easier than Electric Shop, where I regularly burned up almost everything.

oh the irony as an electrician in a foundry
these past few months heh??


You mentioned your thumprint , and IRC
Styrofoam being used as a pattern experimentally at that time. you can imagine what the rough casting looked like from foam that "looked" smooth

I did get to use it to make some truly heavy Brass apple paperweights for the teachers.....sort of a brown nose idea at the time... anything for a better grade huh?

anyway my magnum opus was a Brass cup, saucer, & spoon .... with the spoon inside the cup....., in one pour.
I had to make (3) three part molds.. two were total wrecks, because the cores that I had baked gave way and ruined them.

The last casting was near perfect, but I still had to sandblast, deburr, file, and buff to a high polish... and lacquer coat it. This took a very long time ....but......

I was not allowed to keep it !

..... I was "asked" to leave it for the display case outside the offices of the principal. My "final" grade was dependent on my thoughtful consideration

needless to say, I was really ticked off in 1970, and since mentioning it here, am furious all over again.



[This message has been edited by togol (edited 11-12-2006).]

Beautiful work Alan! Please post pics of any additional finishing that you do. I've just been glancing over what you've done and need to reread to get a better handle on it. I can tell that you love a challenge.
Joe

If I wanted to cast my own silver or copper ingots, what would be the best type of fuel? I've heard charcoal is pretty good, but do they mean the same kind you cook burgers on a grill? How suitable is MAPP gas?
Thanks
-Josh

Copper melts at 1984°F, silver at 1763°F. Mapp gas torches reach that temperature, but when melting up at these temperatures, the power of the furnace is important if you are to succeed- long drawn out heating times with an undersized heat source introduces problems of gas absorption and oxide [or dross] formation. That loss of metal costs money!
I melted [and cast in DRY sand] copper in an iron ladle using charcoal as a boy in the fireplace with our vacuum cleaner on ‘blow’ providing the air blast. Don’t do this as it stinks out the house!

Any BBQ charcoal is fine, but I’d go for a good hardwood natural charcoal brand and not ‘briquettes’ or domestic coals, as you are then assured there is no sulphur in the fuel. This element, if absorbed into either Ag or Cu, will create havoc with any forging or other later work, making the metal brittle [ ‘hot’ or ‘cold-shortness’- as in cookies or pastry].

To get the temperatures required you need to blow air into the furnace with a blower and a tuyau [ let’s use the right words!] or pipe. Iron pipe or conduit is fine, stainless steel is better, as there is less likely-hood of melting the end off! A BBQ charcoal furnace with a blower will easily hit 3500°F, so take care or you can melt the firebricks. And believe me, a plastic vacuum cleaner pipe WILL catch fire!

‘The Furnace’ could be just some firebricks arranged to form a suitable hearth.
Both copper and silver absorb lots of oxygen and other gasses while molten, and these cause the metal to distort or ‘blister’ as the gasses come out of solution upon solidification. You need to melt quickly and then cast. [ Drag any dross or crud floating on the top of the melt off first]. Small amounts of blistering can be cold-forged out by hammering. If extensively cold-working these metals, an occasional anneal with a gas torch up to dull red-hot will make the piece more malleable and less prone to cracking. Let the piece air cool, or walk it with tongs to your water bucket for a quench- but see later paragraph.

Iron from melting-crucibles [ including stainless steel ] will be dissolved a little into the metals, probably not enough to bother you, but the electrical conductivity will be ruined by a very small amount of iron. Similarly, oxides of copper or silver in the cast piece will lower the conductivity and can also lower strength and other properties of the metals, hence the need for fast melt and cast.

If you are serious, there are www. sites which sell proper ceramic crucibles and tongs. Wear proper protective gear against burns [ cotton or leather, not man made ] and most important of all, as Norm says , wear Safety Glasses, because if you encounter ‘blister conditions’, the metals can spit. Do NOT cast into wet sand or damp plaster molds- that risks a steam explosion- in fact don’t have water anywhere near, except perhaps in a fire extinguisher. Working outside is the best plan. For ingots, 'chill casting' into a welded-up mild steel box-mold, with suitably tapered sides for release, would be ideal. Dust with talc or powdered graphite to aid knocking out.

Best of luck, and play safe!

Alan


[This message has been edited by Alan Belson (edited 11-18-2006).]