Casting Lead?

I'd worry about aluminium dissolving in the molten lead. I am not metallurgist enough to know if this is feasible or even likely, but enough metals are mutually soluble for it to be a possibility
Click to expand...
Something I had in mind to check out today. As far as I have been able to discover there is no problem and the aluminium wont dissolve in the molten lead.


If recycling old lead pipes, the presence of a solder join will reduce the melting point of the lead, and you may get tin separating out as the metal cools.
Click to expand...

Tin as such wont separate out. Small amounts of tin form a solid solution with lead. If a molten mix of tin and lead, with less than 62% tin is cooled the lead rich solid solution with form initially The composition of the liquid will become increasingly tin rich as this happens and the temperature falls. At 183C the liqid will contain 62 % tin and will then solidify at that temperature forming the typical eutectic structure.
The tin/lead phase diagram is easy to find , is a very simple one and explains all.
 
I have some plastic drain piping of the right diameter. If I put that in sand I'm presuming it would melt/burn off but would it make a mess of the lead surface? Or Kitchen roll tube: in sand or stand alone Vic?

I reckon for a 1kg lead I need:
Diameter = 2.9cm (giving an area of 6.6cm^2)
Length = 13.4cm (giving a volume of 88.4cm^3)
Lead weighing 11.34g/cm^3 gives 1002g
 
VicS said:
Something I had in mind to check out today. As far as I have been able to discover there is no problem and the aluminium wont dissolve in the molten lead.




Tin as such wont separate out. Small amounts of tin form a solid solution with lead. If a molten mix of tin and lead, with less than 62% tin is cooled the lead rich solid solution with form initially The composition of the liquid will become increasingly tin rich as this happens and the temperature falls. At 183C the liqid will contain 62 % tin and will then solidify at that temperature forming the typical eutectic structure.
The tin/lead phase diagram is easy to find , is a very simple one and explains all.
Click to expand...

I too did a quick check and on a cursory reading, I think you are right - that little significant solution of aluminium in lead occurs until above the melting point of aluminium.

Thanks for the latter; what that means is that the lead rich solid will form initially, with the last little bit being the eutectic mixture when the proportion of tin is 62%. So, although I wasn't exactly correct, it does mean that the majority of the tin will be in the last bit to solidify.

I was working on a recollection that plumber's solder (as opposed to electrical solder, which is a eutectic mixture) is designed to precipitate a lead rich solid first, which remains suspended in the remaining tin-rich liquid, allowing the solder to be "worked" while solidifying.

My knowledge of phase diagrams is mainly in the area of rock-forming silicates!
 
Last edited:
So, although I wasn't exactly correct, it does mean that the majority of the tin will be in the last bit to solidify.
Click to expand...

Well not quite right ... it depends how much tin was present in the first place. The last bit to solidify will have the highest tin concetration ... but that could be a realatively small proportion of the whole.

I thought I had a tin/lead diagram among my Photobucket images but I cannot find it!
 
VicS said:
327 for lead 659 for aluminium should be far enough apart to be able to do it with just a little care esp as by the time you get to 659 it'll glowing red.

Cast iron pan if you have one but i cannot remember what i used.

I am sure i did it at home not at work. A long while ago though
Click to expand...
I agree Vic, the aluminium saucepan doesn't melt if you are careful.

I cast my lead line 'lead' using bits of old lead, a primus stove with an old petrol blow lamp as a extra source of heat to hurry things up and a wooden mould. I've still got the battered saucepan kicking round the garage somewhere. I bent the rim of the saucepan into a suitable shape for pouring into the mould.

I did it outside and was careful to stand up wind to make sure the fumes blew away from me.

The wood does end up a bit charred but what the heck...
 
An aluminium pan isn't going to melt. Unless you have superhuman patience you will be poking the still solid remains of lead pipe into the melt! It will have barely fully melted by the time you are scraping off the slag and getting yourself ready to pour! I would not use anything plastic or paper as you don't know how exactly it is going to burn (which it will). The idea of using damp sand fills me with horror. The first time I did lead weight making as a 14 year old I made a cement mold and didn't let it fully dry, although it had fully set. The result was a shower in molten lead! It's like putting an egg in a microwave, as a drop of water boils it has nowhere to go until it has enough pressure to blow the molten lead off, in your direction.
 
I used to cast sea fishing weights (conical, 1/2lb - 2lb) using a camping gaz stove, aluminium saucepan and a split aluminium mould. Easy and pretty safe if you're clean, dry and careful. I've also cast thousands of bullets using similar equipment and a "spoon" to fill the mould - although for this we used an extractor hood indoors so as to keep the melt going. Treat the materials with respect and you should have no problems, but I prefer an aluminium mould. Often the remains of the melt was poured into a tin can and it would solder itself in! Perhaps one of these designer drinks cans (tall and thin) would be just the job?

Rob.
 
I cast some dive weights using a frame made of wood. It scorches, but no real problem. A camping stove may be OK, but I made a brick kiln to surround my gas blowtorch; that way the heat is contained and it keeps the wind off.

I've got to repeat the exercise soon with zinc, to make a hanging anode. For that I'm using a mould of sand and a little cement I made last year, should be dry by now!
 
Over the years I have cast hundreds of weights and pirks using an aluminium saucepan, no problems. If you want a particular diameter, saw a steel tube straight down its length, then put a jubilee clip at each end to hold it together, you will have no problem releasing the mould.
When it comes to moulding lead in a milk bottle top so that it fits into a ciggie machine, solder is better!
 
Too easy Vic!

Saying that the scrap value of the lead I have must be more than £18.99 :rolleyes:

Today is the big day, further replies may be slow coming as I will probably be typing with the stub of a finger and reading through a bandaged face...

One more technical question: I was going to put a clingfilm roll holder (like toilet roll but stiffer card) into a bucket of sand as a mould. I have some 4mm diameter brass tube which I am planning to stick through the top of the cardboard and pour the lead around it, to give a hole for the line. Any potential problems with this? Will it be secure when cooled?


Also whats the best way to tidy up the finish, filing, sanding? :eek:
 
Last edited:
VicS said:
There is a quick and easy way of avoiding all the potential hazards mentioned in this thread

SEE HERE

:)
Click to expand...

Hmm, might get one of those.

On those occasions when I've felt it necessary to do it the man's way, I tend to hang a large spanner off a fishing line. Admittedly, the only times I've felt the need to do this were when the sounder seemed to be giving silly figures.
 
Well that went quite well. Cut up the lead (old flashing) into small squares and it melted within a few minutes. The card tube was wrapped in aluminium foil but hardly even scorched.

Finished weight is a scratch under 2lb (815g).

If I did it again I would put the thread hole in the bottom so that the cooling caused a dimple in right end for 'arming'. As it was I hacksawed the top off instead.

Thanks for the input.
 
Similar spiral pattern on it to mine.

I cut shoulders at the top and then drilled for the line. I bushed the hole with a piece of copper tube ... seemed a good idea at the time.

Had mine for 34 years ... never used it !
Once lent it to someone whose echo sounder had packed up .... he still ran aground in fog on West Pole.
 
You must log in or register to reply here.

Other threads that may be of interest

O
One for the plumbers
Replies
9
Views
381
Overandunder
O

Share this page

Top