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Old Mar 27, 2011, 11:04 PM
planepainter
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Mt. Juliet, TN
Joined Sep 2008
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Question
How do I make a lead mold?

Hi guys. Well, my New Spirit 2 meter is flying just the way I like it. The balance is perfect and I love flying it nearly as much as my OLYIII!
But the weights I have for the forward battery compartment are a pain. They consist of two small plastic bagletts with lead shot balls in them. I can get them in next to the battery but it is always a chore and they can shift because they are, after all, lead shot balls.
How can I make a mold so that I can melt the lead and form it to the compartment? I figure that way I can get the battery and weight in and out easily and the weight is less likely to shift if I make it right.
Thanks as always, Donald

my camera sucks....
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Old Mar 27, 2011, 11:32 PM
Duane
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No. VA
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http://www.rc-soar.com/tech/casting.htm
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Old Mar 27, 2011, 11:48 PM
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United States, CA, Gardena
Joined Oct 2004
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I've done it several ways. Depends on the shape of the cavity. If it's square, I make a box out of scrap wood (like pine or fir). A round cavity, I drill a hole in the scrap wood. If no large drill, I form a piece of aluminum foil, like a miniature cupcake cup.

Using scrap lead (like wheel weights) I melt it with a torch and let it drip into the mold. Do this OUTSIDE!

Other methods-
Line the cavity with foil or plastic wrap. Mix lead shot with epoxy and pour into the nose. You can pour directly in the nose, but make sure you're under weight! It's a lot easier to add than remove. Advantage of the last method is that it adds to the strength of the nose.

If you need a nice looking cast weight, or multiple castings, I make a mold out of HydroCal plaster, melt the lead in a cast iron pot and pour the part.

Last one - I buy sheet lead from McMaster-Carr and cut pieces to fit.

In 50 years of model building I've done all these! Plus just put a lump of modelling clay on the front!

- Norm
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Old Mar 27, 2011, 11:58 PM
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Or take a small sandwich baggie and put the lead shot in it. Mix some 5 minute epoxy and put it in the baggie with the lead shot. Kneed it well in your fingers and put it in the nose and push it in well with your fingers. When cured remove the bag and excess epoxy. You can also use tungsten powder mixed with the epoxy in place of the lead shot. Less volume for the same weight.
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Old Mar 28, 2011, 12:16 AM
3...2...1...See'Ya!!!!
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Minneapolis
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I've always stuffed Aluminum foil into the area I want to put the lead, then I take that "plug" of foil, and wrap more foil around that to make a mold, remove the plug and pour melted lead into the "mold" you created.

Also, if you need lead in the nose of a fiberglass fuse, I've heard of putting the nose of the fuselage in ice water and then pouring the lead directly into the fuse without any problems, although I've never done this.

--Jeremy
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Old Mar 28, 2011, 12:33 AM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
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Quote:
Originally Posted by jrbackus View Post
I've always stuffed Aluminum foil into the area I want to put the lead, then I take that "plug" of foil, and wrap more foil around that to make a mold, remove the plug and pour melted lead into the "mold" you created.

Also, if you need lead in the nose of a fiberglass fuse, I've heard of putting the nose of the fuselage in ice water and then pouring the lead directly into the fuse without any problems, although I've never done this.

--Jeremy
I have done this several times. As long as you just drip the lead in, the cooling of each drip occurs pretty quickly and there's no problem. If you pour it in, you're gonna melt the nose.
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Old Mar 28, 2011, 04:12 AM
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And if you ever miss and drip the lead straight into the water.........
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Old Mar 28, 2011, 09:25 AM
Hot Dawg Glider Pilot
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United States, TX, Weatherford
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Quote:
Originally Posted by lesterpk View Post
And if you ever miss and drip the lead straight into the water.........
I thought of that when I did this. I had forgotten this piece. I used a wet towell full of shaved ice instead of water... much safer! Thanks for the reminder!
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Old Mar 28, 2011, 10:06 AM
planepainter
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Mt. Juliet, TN
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As usual, great stuff from the best glider guys in the world. Pouring the hot lead into the cavity is not an option because the fuse is hand crafted out of balsa and spruce and reinforced with light fiberglass cloth and epoxy. I could form a "cupcake" mold out of aluminum foil and pour it separate. Does the foil come apart from the cooled lead easily? The safer way would be to use small lead shot and epoxy. But I would have to be sure the weight was the same as it is now. I do have a good scale so that would not be a problem. I would like to be able to remove the weight at will. The weight and battery sit side by side in a rather small cavity.
Originally when I built the pod I laid everything out the was to be internal then built the pod around all of that so room is at a premium.


PP
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Old Mar 28, 2011, 12:17 PM
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Go to your favorite home center and go to the shingles area and buy solid lead roof pipe/ flange. You use the flat part that fits between the shingles and cut with scissors and mould with fingers or light hammer. The pipe part is round and you can just cut it up. Or you can melt it into a mould. Wash hands well after handling soft pure lead.
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Old Mar 28, 2011, 12:30 PM
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Steinbach, MB, Canada
Joined Nov 2004
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Hi guys, my suggestion here would be to visit your local hardware store and acquire some Plaster-of-Paris, firstly you could mix the plaster into a very liquid paste, put a plastic bag into the area and then pour the mixed plaster into the bag. This makes a posative mold. From that you will need to remove once hardened and make a negative mold, possibly with 2 sides, so make another two seperate pours with lubricant on the mating surfaces. Once the negative is dry, you will need to place it in an oven at a low heat for a few hours to totally dry them out. Then simply pour hot lead into mated negative forms and once cooled, PRESTO, you a complete form.

Hope this helps, I have used this to mold a lead keel for a sailboat.....worked great.
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Old Mar 28, 2011, 02:19 PM
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Any Flying Field Across America
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I recently considered making a lead slug to fit a particular shape as well and decided to go with the epoxy, birdshot, plastic baggy route. It's simple, gives the exact shape you need, and doesn't jeopardize the fuse in anyway. My suggestion is do use really tiny birdshot like #9. It' a little bit bigger that a period displayed on this website, and it's readily available at just about any gun shop, which all 2nd Amendment abiding Americans should visit on a quarterly basis
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Old Mar 28, 2011, 02:33 PM
Sailplane Hoarderer....er
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Canada, BC, Abbotsford
Joined Jul 2005
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Sackie, there are no sailboats in Manitoba!

Molten lead and water can be a recipe for serious bodily harm! Do not use water to get the dust out of mould. If there are even a few drops of water in the bottom of your mould they will be sealed by the thin layer of rapidly cooling lead. At the same instant that little bit of water will turn to steam, increase in pressure and blow the cap off the thin layer of lead. By this time there is more molten lead on top which is ejected at a rather significant velocity. This is first hand experience, I have a fleece jacket that has a little dots of molten lead all over it... kinda looks like sequins.
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Old Mar 28, 2011, 04:01 PM
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Steinbach, MB, Canada
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Quote:
Originally Posted by Ryan2200 View Post
Sackie, there are no sailboats in Manitoba!

Molten lead and water can be a recipe for serious bodily harm! Do not use water to get the dust out of mould. If there are even a few drops of water in the bottom of your mould they will be sealed by the thin layer of rapidly cooling lead. At the same instant that little bit of water will turn to steam, increase in pressure and blow the cap off the thin layer of lead. By this time there is more molten lead on top which is ejected at a rather significant velocity. This is first hand experience, I have a fleece jacket that has a little dots of molten lead all over it... kinda looks like sequins.
NOT true Ryan, I have Four (4) in my basement,,,,,just now awaiting the THAW so I can go sail them....yes, I concede, they are few and far between, but there are some of us that on days that would be considered TOO WINDY to fly, we can still have some R/C fun....though it may be all alone...I suppose I may be considered an absolute modeller, the only R/C type model that I have not had over the years is a Heli, just because I do not, and have never had any interest in Heli's...Cars, Boats, Planes, Sailplanes, either have or had...

I had stated to make sure and dry out the mold fully before using. But by making it able to be split, will enable the making of multiple weights from the original pour. If you do not dry out the Plaster fully, it WILL crack once the hot lead touches it, but usually there is not sufficient moisture still in the palster to make the lead pop. However, that will depend on how quickly someone is attempting to pour in the molten lead.

By the way Ryan, where are you located?
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Last edited by Sackie; Mar 28, 2011 at 04:17 PM.
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Old Mar 28, 2011, 04:44 PM
cuz real planes cost too much
USA, CO, Frederick
Joined Jan 2011
850 Posts
hey donald, do they weigh as much as a motor/spinner/prop?
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