Ballast keel mold

[kng]

Hi how are you ?? I would like to know or have advices about making the lead ballast for my Grey Seal, I have the "male" mold built with expanded polyurethane and I would like to make the "female" mold to pour the lead into... with concrete, I would like to know the width of the walls of the mould and if I need to put steel wires to prevent breaking the mould at the pour moment... and If I will have to put the mold into a bed of sand...
thank you very much !! I will try to upload images of the mould I have now..
thanks !!
Emiliano. http://personales.ciudad.com.ar/kng/ballast.jpg http://personales.ciudad.com.ar/kng/ballast1.jpg

[ 09-26-2005, 11:01 AM: Message edited by: kng ]

[wyndham]

Pouring hot lead into a concrete mould sounds like a recipe for disaster. Unless ou can be 110% absolutely sure that there is no retained moisture in the concrete, which is just about impossible, you are going to have hot lead and chunks of concrete flying around and hurting you and anyone in the immediate area.
There are a number of good informative strings that pertain to pouring lead keels.
You need to rethink your options here.

[Dave Fleming]

Here is some interesting info and comments.

Lead 101 (http://www.woodenboat-ubb.com/cgi-bin/UBB/ultimatebb.cgi?ubb=get_topic;f=1;t=004818)

PS: That is from the FAQ.

[ssor]

Plaster would be a safer option but it would still need to be preheated to avoid steam explosions. Sand allows the steam to escape gently.

[Bob Cleek]

That is a very easy shape to cast. There is no reason to go to the trouble of trying to make a pattern for it and then a casting. But... if you must, there are a couple of ways to do it.

One, use your pattern and casting sand. Of course, you will have to build a box for the sand, so it is easier to build a box for the lead.

Simply build a box the shape of the keel out of "two by" dimensioned stock. Looks like a two by eight or twelve should do it. You can get the rocker on the bottom with plywood, built up in several thicknesses. Yes, you should tie the tops of the mold together so they don't spread when you pour. Lead is amazingly heavy and will do that. You can coat the mold with a refactory material or even plaster of paris. Make sure there are no leaks. When you set up your mold, make sure the top edges are level and plumb. Then when you have finished the pour, you can take a router mounted on a plank and just rout the top of the casting perfectly fair. (you'll have a bunch of dross and whatever on the top when it cools.)

And, by the way, from the looks of the picture... did you allow for shrinkage when you lofted your pattern?

[Jay Greer]

By all means, you will not dance with the devil is you use moulding sand and build a well banked and shored re-inforcement dam around the mould.

I once knew a fellow who thought he would save time money and effort by moulding his keel below grade. six thousand pounds of lead went into the pour. But, there was a hang up in the process inspite of all the planning and effort to dig and pack a clean form, the gophers in the lot had mined the project. It took a month for old "Squeeky" to dig out his lost lead and start anew.
JMG

[Canoeyawl]

I have poured some of these small lead keel castings and here are a few things to consider…all of them learned the hard way
1-Howard Chapelle is wrong, do not wet a wooden mold (don’t ask, it was thirty years ago, everyone is OK)
2 – If you use a sand cast lead keel some sand will float up into the lead and you will not be able to plane it. It also resists grinding and sanding.
3 – lead shrinks equally in all directions at about ¼ inch per foot - the mold needs to be longer and wider than the space allowed.
4- a simple “flat top” casting in a dry wooden box poured at the lowest temperature will work fine for that piece. Oriented with the most surface area to the air if possible. There will be some smoke but nothing to worry about. Do not overheat the lead.
5 – Beautiful boat…

[kng]

Hi !! thank you very much for the advices... I was sad about all negative answers but for sure real... Im thinking about the air bubbles at the concret (1) and breaking apart becouse of the weight of the lead (2) as the worst part of this.. I was thinking to build a female mold like esculptors make with plaster like someone says above (sorry dont remember name)adding the concrete like some fluid and leting the air escapes.. and drying it very well... I have the experience of weting a wood mold I made to a daggerboard... and the vapor explodes and is very dangerous ... I won´t make it again for sure..

I think Mike Pilato made for his Grey Seal a concrete mold but I have lost his e-mail...
my other worry is about the weight of lead breaking the walls of the mould thats why I asked the width I should use...
I have found this link to the glen-l site what do you think about it ??
lead keel (http://www.glen-l.com/misc/lead-keel-2.html)
thanks again to all for the advices..

Emiliano.

[ 09-27-2005, 12:43 PM: Message edited by: kng ]

[Canoeyawl]

The rate of shrinkage allowance for lead castings is 5 /16in per foot
(Source-Machinery’s Handbook)
With a ballast casting say 6ft long this will be about 30/16 or 1-7/8” !!! If you make an exact pattern to fit the void in your boat and cast from it the part will be to short and to narrow. Your pattern should reflect the shrinkage allowance.

[Bob Cleek]

And while you're at it, read this web page before you start melting that lead!

web page (http://www.anvilfire.com/iForge/tutor/safety3/)

[ 09-27-2005, 11:35 PM: Message edited by: Bob Cleek ]