MM5AHO
Well-known member
How are you going to obtain the 2800 odd degrees heat to cast steel DIY???:ambivalence:
1750 degrees would be enough.
Casting a keel
- Thread starter pmagowan
- Start date
1750 degrees would be enough.
lukedh
New member
It has been done many times by Eventide Owners, one account is given here: http://www.eventides.org.uk/lead_keels.htm
Lucy
Lucy
knuterikt
Active member
I contemplated a DIY cast of a lead keel for my Andunge some years ago, had access to the original plug for a casts iron keel, together with a naval architect we calculated where the line to get the same weight in lead as the original iron keel.
I ended up getting the keel made by professionals (when trying to get hold of suitable lead I was told that the price I was quoted on a keel was so good that DIY was not a good business).
The pros use spacial dry casting sand for small series,
The plug (model of the keel) is placed in a steel box and the sand gets packaged around the plug,
Then the plug is removed and keel bolt "mould's" is inserted into the sand form together with SS reinforcements (rectangular SS washers), this boat has got keel bolts with nuts recessed into the bottom of the keel.
They melted the lead in closed thermostat controlled pot to avoid overheating the lead (with release poisonous gas), I was told the they didn't need protective equipment during the pour.
But when they sanded the surface afterwards they looked like astronauts.
All the employees had blood tests taken regularly to check for traces of lead in their blood.
During my research I looked for different ways of making the form, what i learnt was that it important that the form is bone dry as the melted lead will make steam of any water present in the form this can make the lead splash boil with catastrophic results.
I was told that some have used concrete forms with good results - but it's important that the concrete has dried completely before pouring.
This is the company I used http://www.oerkild.com/html/engelsk.html some useful information there.
I ended up getting the keel made by professionals (when trying to get hold of suitable lead I was told that the price I was quoted on a keel was so good that DIY was not a good business).
The pros use spacial dry casting sand for small series,
The plug (model of the keel) is placed in a steel box and the sand gets packaged around the plug,
Then the plug is removed and keel bolt "mould's" is inserted into the sand form together with SS reinforcements (rectangular SS washers), this boat has got keel bolts with nuts recessed into the bottom of the keel.
They melted the lead in closed thermostat controlled pot to avoid overheating the lead (with release poisonous gas), I was told the they didn't need protective equipment during the pour.
But when they sanded the surface afterwards they looked like astronauts.
All the employees had blood tests taken regularly to check for traces of lead in their blood.
During my research I looked for different ways of making the form, what i learnt was that it important that the form is bone dry as the melted lead will make steam of any water present in the form this can make the lead splash boil with catastrophic results.
I was told that some have used concrete forms with good results - but it's important that the concrete has dried completely before pouring.
This is the company I used http://www.oerkild.com/html/engelsk.html some useful information there.
Tranona
Well-known member
To get the kind of density you need, lead is really the only practical material for DIY, either cast or poured into a steel box frame. Clearly the latter has constraints on shape, but the source I referred you to shows how you can get an aerofoil shape. Usually the lead is strong enough to use studs as used in iron keels, but through bolts are also used with holes cast in, but with some designs you end up with very long bolts so an alternative is to cast pockets in the keel for access to nuts and the bolts come in from the top. Pockets are filled when the nuts are tight. Deep foil shaped keels with ballast bulbs at the bottom, common on many modern boats often have a stainless steel framework cast to carry the loads.
So, lots for you to think about when designing your keel.
sailorbaz
Member
When I was a lad and started out as a metallurgist, I worked in an experimental aluminium foundry. We often made our own cast iron dies for casting aluminium into. We did this by breaking up old dies with a sledge hammer and melting them in a crucible in a pit furnace. IIRC we heated the iron to 1450 deg.C and added a magnesium-silicon alloy which resulted in a nodular graphite structure so that the casting was not so brittle.
The maximum size crucible which would fit in the furnace held 300 lb and was lifted with the crane and lowered into a yolk which two of us held to pour the iron into a sand mould. We wore protective clothing - probably made from asbestos - but I still ended up with blisters on my hands!
As has been mentioned in other posts, for steel you have to go to even higher temperatures.
The swing keel on my boat is cast iron and weighs 1500 lb which is much less than a lot of fixed keel yachts and to cast that you would need access to a foundry with a crane, and much bigger furnace than the one we used.
Any casting needs to be cast in one go - you can't half fill the mould and then do another melt to top it up as you would have what is known as a cold shut. This would be a line of weakness and the bottom half would probably drop off!
Sailorbaz
The maximum size crucible which would fit in the furnace held 300 lb and was lifted with the crane and lowered into a yolk which two of us held to pour the iron into a sand mould. We wore protective clothing - probably made from asbestos - but I still ended up with blisters on my hands!
As has been mentioned in other posts, for steel you have to go to even higher temperatures.
The swing keel on my boat is cast iron and weighs 1500 lb which is much less than a lot of fixed keel yachts and to cast that you would need access to a foundry with a crane, and much bigger furnace than the one we used.
Any casting needs to be cast in one go - you can't half fill the mould and then do another melt to top it up as you would have what is known as a cold shut. This would be a line of weakness and the bottom half would probably drop off!
Sailorbaz
oldsaltoz
New member
I have a suspicion that my brother cast the lead keel for my boat. All he knows is that they were being exported to Germany, but it was around the right time. I've meant to get him to look at it when the boat is out of the water to see if he would recognise it.
It was a commercial operation though and even then he left because he was starting to suffer from leadForget about casting in steel, you will more money than the keel is worth generating the heat required.
I had a hand in casting a lead keel some years ago for a 34 foot racer.
Bits list.
Plug for mould (laminated scrap timber)
Mould box, 3/4 inch ply and lot of bracing on both inside and out.
Suitable sand with oil added.
Internal keel frame, stainless steel incorporation a 3 inch tube with cut outs to allow the lead to flow out at all levels as it filled, this was welded to the keel plate with all stainless double welded nuts and bolts.
About 20% more lead by weight than you calculate you will need.
A person or persons with experience of building mould for this application.
Lots of Gas and several (4 minimum outlets to provide the heat.
We used an old cast iron bath as a melting pot with a stopper over the drain hole on a long steel rod to control the flow.
The bath bottom must be at least a foot higher than the top of the keel plate with delivery chanels to the mold, we used old steel guttering and large steel pipe cut in half to form troughs.
The bottom 3 feet of the mould was bellow ground and the ground was compacted.
Getting enough scrap lead was problem, we ended with a lot of lead containers that used to contain Isotopes, surprisingly the keel did not glow in the dark?
THINGS TO LOOK OUT FOR.
We developed a small leak, perhaps 2 Kg at ground level, also after cooling we realised one side was a little rounder than the other, so spent a couple of hours with an electric planer and profile boards to put it right. Though we saw no movement it must have, and the box was as solid as a rock.
Would I do again, perhaps but maybe not quite a large a project next time.
Fro let's do it to completion was just under 3 weeks. and most of that was just 2 of us working on it. On the big day we had 8 people, though 4 were mostly spectators, but there in case we needed them.
Good luck and fair winds.
pmagowan
Well-known member
Thanks guys, sounds interesting. I could probably get hold of lots of scrap lead. Making a furnace shouldn't be too tricky using some steel tubing, blowers, diesel and gas. The problem is the crucible but I supposes large bath might do it, or perhaps two. Re the mould, what about digging a hole and putting a polystyrene plug in then compacting round it with casting sand. When you pour the polystyrene will simply disappear.
I need to make a small furnace for casting bronze etc anyway so I can get used to the methods prior to the keel.
I need to make a small furnace for casting bronze etc anyway so I can get used to the methods prior to the keel.
Rigger Mortice
N/A
It's normal to take the plug out rather than burn it out. The sand should be able to retain the shape.
There's always lost wax casting; what you are suggesting is lost polystyrene casting!
There's always lost wax casting; what you are suggesting is lost polystyrene casting!
DownWest
Well-known member
Friend worked with a sculptor. Polystyrene was a common plug, not need to remove it, just don't niff the fumes.
pmagowan, there are several sites about casting. I have two how-to books about it. One is for bronze and the other waste oil for iron. I will look them out and link them.
Not rocket tech, quite simple.
DW
JumbleDuck
Well-known member
pmagowan
Well-known member
I thought polystyrene would work quite well because it is easy to shape and you can make a plug with overhangs such as a bulbous foot. It would disappear very quick once the lead was poured. Alternatively you can pour a little petrol on it and it melts away. It would make the moulding part easy, like the lost wax method but without needing to drain away all that wax. Of course I need to calculate the size and shape of keel first before I know how much lead is required. The idea of a back yard foundry is quite fun though!
Rigger Mortice
N/A
This might be of interest. http://en.wikipedia.org/wiki/Lost-foam_casting
Have you worked out which church roofs you are going to raid for the lead?
Have you worked out which church roofs you are going to raid for the lead?
DownWest
Well-known member
Here's one: http://www.artfulbodgermetalcasting.com/ I seem to have misslaid the other for the moment, but it was an ozzy guy's CD on a gas fired furnace.
macnorton
Active member
Helped my dad build one a few years ago.
Built the frame from steel and suspended it on steel beams over a bonfire, threw the scrap lead in and as it melted removed the rubbish from the top with a ladle.
Once cooled it was fitted to the boat with a grp cover and the void filled with resin mixed with chalk to make it set slower.
Pacesetter 28 called "Gentle Breeze" if anyone knows where it is now?
Built the frame from steel and suspended it on steel beams over a bonfire, threw the scrap lead in and as it melted removed the rubbish from the top with a ladle.
Once cooled it was fitted to the boat with a grp cover and the void filled with resin mixed with chalk to make it set slower.
Pacesetter 28 called "Gentle Breeze" if anyone knows where it is now?