Casting my own lead keel

[tiz]

I am shortly to cast a half ton external lead ballast keel. I would welcome any general advice and specifically what does the addition of antimony do? I have been advised to add 10% to the lead, but since I am using some reused scrap lead and some new offcuts is this likely to have antimony in it already?
Having thought long and hard I have decided to cast the keel in a plywood mold. Having done a small test casting I found the plywood is unlikely to be seriously damaged at least until the lead has solidified. Any comments?

Phil

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[tcm]

Without antimony, the lead will be weak and likely to creep - or in the case of a keel probably likely to become a longer keel and eventually fracture and fall off.

Another consideration is that molten lead will exert big sideways forces on the mould so the plywd box will need to be superstrong - lead is 10ish times heavier than water hence forces in liquid state 10 times greater, so the mould has to be 10 times stronger than an equivant depth aquarium. Praps reinforce the mould box with concret blocks around, or make the box fit tightly in a concrete hole.

I spect the keelbolts should be part of an internal frame, in the style of steel reinforced concrete, but dunno.

good luck!





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[ShipsWoofy]

I used to make my own fishing weights. I understand a totally different ball game but

Be ultra careful of the lead exploding if it hits cold or damp when you are pouring it.

Wear big gloves, face mask, and cover all skin, when it goes it goes and I am talking about a saucepan full.

Out of curiosity how are you going to melt and transport that much lead in a molten state to pour in to mold in one. Or are you hoping to build it up in stages. 1/2 ton of hot molten liquid is going to be fun init!

<hr width=100% size=1><A target="_blank" HREF=http://www.topcatsail.co.uk>Woof</A>

 

[roger]

I remember an article in PBO many years ago about casting a keel in a steel mould where the lead was melted in the mould by means of a furnace underneath it. It avoided movinb molten lead about.
Fumes of lead and especially antimony are going to do you no good at all.

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[steve28]

i watched it being done, the keel was for a gollant gaffer. The process used was a wooden casing with straps around the outside then blocks around that.
The first time was disasterous as the vessel used for the lead was a steel bath, the plughole melted and the lead went very quickly everywhere.
The second attemp was 100% ok and the keel was perfect.

slight finishing was needed to take any imperfections out.


steve

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[Gordonmc]

I am answering only from use of lead in hot metal printing where antimony was added to act as a flux so the lead would flow into type moulds. If you plan on using roofing or plumbing lead I would guess it does not contain antimony.
I recall reading about a guy in South Africa who build a lead foundry in his garden to cast ingots for ballast using plumbing lead... it was likely in PBO so an article search might turn something up.

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[richardandtracy]

If you cast around steel re-inforcing rods you'll have no worries about creep, and no need for antimony.

Do invest in a P2 mask (toxic dust) and use it when melting. There is no point in poisoning yourself.

Regards

Richard.


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[goneballistic]

Have no experience myself but while thinking about the same question I came across this. www.rutuonline.com This guy cast his own keel for quite a big boat. Goes through it step by step and even explains the score with the antimony. Hope its helpful.

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[kingfisher]

Safety issues

How can I stress the use of the proper safety precautions before starting to cast hot metal....ah, an image might do the job...

<hr width=100% size=1>Group of people on the pontoon: skipper is the one with the toolbox.
http://sirocco31.tripod.com

 

[pissativlypossed]

Fumes are a major problem, Lead and its alloys are (obviously) heavy metals and extremly toxic, the problem is that the effects are cumulative, the body is unable to purge itself of heavy metals, you will not only have lead to contend with but also lead compounds, most scrap lead will have been reworked over time and is likely to consist of compounds of cadmium, tin,berylium and others. All very nasty and highly toxic. There is no mask available, other then a positive pressure ventilator,that will protect you. Be aware also that it is illegal to melt lead without an authorisation from your local authority and defra, and they are not known to hand these authorisations out lightly.

<hr width=100% size=1>"Open Another Bottle"

 

[richardandtracy]

'Be aware also that it is illegal to melt lead without an authorisation from your local authority and defra..'

Didn't know that. Obvious solution is not to know it in the future too.

Regards

Richard.


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[tiz]

Thanks for all the replies so far, particularly those concerned about safety issues. In reply to Ships Woofy we are casting in a cast iron bath with an outlet welded to the plug hole this brought out to a swivel and thus the spout is up, and above the level of the lead during the melt and lowered on a chain to pour. This system was successful when casting a friend's three and a half tonne keel. This was an internal keel for a GRP hull so the antimony wasn't an issue,nor was the finish. Also this was cast open in a weak concrete mould.

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[oldsaltoz]

G'day Phil,

The last keel we made was about 5 years ago, we used a bathtub and had the plug on the end of a steel rod to control the flow, worked ok.

Heating was done with gas and 3 very large lances made up by a local gas fitter, the lead was mostly scrap and we added antimony as well.

The keel was cast in a heavy 2 inch thick timber box with 4 inch braces every 10 inches right around it from top to bottom, the bottom of the box was dug into the ground about a foot to 18 inches and 4 large stakes driven in and secured to the sides of the box to prevent any movement.

Inside the box we has a mixture of sand and oil that had been compacted around a timber plug of the keel. When this was removed it was replaced with a stainless steel tube about 2 inches in diameter with large holes cut out evert 6 inches to allow the lead to run out but not damage the sand/oil mix; at the top of the tube a s/steel plate held the keel bolts in place.

It took about 90 minutes to get the lead heated up and only 10 minutes to run it into the keel, we stripped it the next day and had a couple of small areas with sand contamination, very minor, removed and re filled with a small gas flame.

Points to ponder: everything must be very very dry. Make sure you have a good mask, eye protection, we used the full face shield jobs. Check the wind direction and make sure nothing or no one is downwind. build an earth dam around the mould to contain any spills or ruptures and please wear some solid boots that can be removed in a hurry if required.

I recently re shaped a lead keel, adding a torpedo to the base a taking about an inch off further up, I used a standard electric plane, did a great job in no time at all.

Avagoodweekend.....



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[chuns]

How not to cast a keel...

...A friend of mine (sadly now dead) once cast a long, thirty foot-ish keel for the boat he built.

Now he lived at the top of a hill, but he wasn’t stupid, so he constructed a very strong box, and made sure it was dead level. His mistake was to pour a lot of lead in at one end of the box, which itself was about 18 inches wide and a foot or so deep. The lead ran along the box till it got to the end where it promptly beat the end out of the box, ran across his lawn, down his drive, across the pavement and out into the road where it flowed down the edge by the kerb. Some went down a drain, but he was able to peel the rest off, once it had solidified, and start again.

This same friend turned the boat he built upside down outside his house using parbuckles. He had decided, after a few seasons, that he didn’t like the cockpit he had built so he took a chain saw to the stern. Mind you his woodworking skills were so good that you never would have known.

Imagine all his downhill neighbours anxiously looking up at him rolling this bloody great boat over!!

Sadly missed.


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