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konsole
06-08-2014, 02:42 PM
Here is my situation...

I've metal detected for about 10 years, not all the time but off and on those years. Over those years I found around 3 lbs. of lead fishing weights. I can't remember what got me interested in this, but I decided it would be fun to melt down the fishing weights into some interesting shape. I guess I finally decided to do it because I found out how low lead melts at, and how since its so heavy almost all the other material float to the surface and can be skimmed off. The ease of melting the lead and making it very close to pure, combined with the fact that a real basic setup is all thats needed, I decided to try it. I melted the 3 lbs. of fishing weights inside a small aluminum dish on a coleman stove and I thought it was alot of fun doing it. Now I realize that aluminum isnt smart to use so I'm certainly not using aluminum as my melting pot anymore. After that I found out that lead wheel weights can be found at auto shops for free or sometimes very cheap. Near me is a large strip of auto shops and dealerships so I went around to all of them asking for their weights. In about 3 hours of driving around I accumulated about 150 lbs of wheel weights. I found out which are zinc and which are steel so I separated those out, and I was left with about 100 lbs of lead. In place of the aluminum melting pot I got a couple mini steel bread pans.

The end product I am looking for are ingots that are as smooth and uniform as possible. I'm not looking to make bullets or fishing weights, just bricks of lead that I guess could be used as doorstops, or just sit on the shelf as decoration or conversation pieces :-). The chances of going out and finding more lead to melt is slim at this point since I have no important use for them, but I can't say I definately won't go looking again at some point.

The 8 lb bricks I have made so far I have been able to get within 1 oz. of 8 lbs. on them (8 lb. on the dot isnt critical), however the main issue I am experiencing is the top of some of the bars cave in way too much when they solidify, and the cave in is a fairly steep drop right around the center of the bar. I know its somewhat unavoidable to completely eliminate because all of the bars have experienced some caving in. Also I know that some caving in is typical of "poured" type bars. Other then the sharp caving in too much on some bars, overall the bars have come out very nice.

I figured the deep caving in maybe had something to do with cooling off too fast, so I went from high heat to get the lead fully melted, to medium heat for a minute or two, then to low heat for a minute or two, then to no heat, but the bar still experience alot of caving in when it solidified.

Any tips on how to prevent the deep caving in on the top of the bar when they solidify?
Also why are my 8 lb. bricks so hard? I'm sure my bricks arent 100% pure lead but I would have guessed that they are 95%+ and would be softer then they are. (the bricks are roughly 5"x2"x2" just so you know)

bruce381
06-08-2014, 02:48 PM
I think the higher the "other" alloys are the more shrinkage as the lead cools. or maybe other way around.

For apperences sake maybe try a propane torch on the tops after they are solid but still hot.

Wave the torch flame over the solid shrunk in spots to re melt just the top and give it a smooth finish.

twc1964
06-08-2014, 07:42 PM
Just remember that it is lead. you don't want the family pet knawing on it or using the corners as a back scratcher. don't think you would want lead particles spread thru your home. just sayin.

dikman
06-08-2014, 07:47 PM
If you're using mostly clip-on wheel weights, that's why they're hard - antimony and tin.
Bruce's idea is worth a go to try and smooth it out, otherwise you'll need a mold to pour into so that you can leave a "pool" of lead at the opening to hopefully allow it to fill in as it cools.

gtgeorge
06-08-2014, 07:58 PM
Find a metal plate that will lay over your pan and form a decent seal. Then drill a hole and countersink it like a mold plate would be. Then heat it all up before filling the remainder through the hole leaving a generous sprue on top. That will be what the cave in draws from to prevent it. Basicly look at a bullet or other molds for ideas to follow.

RogerDat
06-08-2014, 09:37 PM
The propane torch trick as it is cooling works to melt the higher edges back into the center.

If I read what you wrote correctly you are not pouring into the bread pan as a mold but doing the melting in the bread pan. Might try picking up a stainless steel pot and ladle from thrift store or discount store and pour the lead into the bread pan using the ladle.

Have the bread pan mold pre-heated a bit but not all the way to melting point of lead.

konsole
06-09-2014, 04:10 AM
So there is no simple method of removing the tin and antimony from the melt? I'm guessing simply keeping the heat up and continuing to skim the stuff that accumulates at the top of the melt wouldnt remove the tin and antimony?

dikman
06-09-2014, 05:37 AM
Constantly heating it will cause some of it to precipitate out, but you'll never remove all of it. As to how much it will reduce the hardness I have no idea. If all you're trying to make is a doorstop/paperweight then the hardness shouldn't matter.

konsole
06-09-2014, 12:20 PM
I'm pretty sure I don't have any zinc in the ingots because I sorted all the zinc out beforehand, and also I did manage to pull out a couple zinc weights from the melt before they melted. I'm not 100% sure there isnt any zinc in the ingots though.

Lets say I currently have ingots that are lead, tin, antimony, and possibly zinc. Let say that that I then melt the bar at 700 'F.

Since tin melts at 449 'F, but is lighter then lead, could the molten tin be skimmed off the top of the 700'F lead?
Since zinc melts at 787 'F, and is lighter then lead, could the solid zinc be skimmed off the 700 'F lead?
Since antimony melts at 1167 'F, and is lighter then lead, could the solid antimony be skimmed off the 700 'F lead?

Perhaps a little agitation of the lead might be require to get tin, zinc and antimony to rise to the top, but would those 3 things work?

RogerDat
06-09-2014, 05:03 PM
I have an idea. Instead of trying to get rid of the very alloys we want for casting maybe you should consider swapping yours for some plain lead.

Your minute or two of lower heat settings in first post won't make any difference to the temp of your lead. Molten metal does not cool all that much just because you reduce the heat for a "couple" of minutes.

While people will say "soft" lead the material is still a metal so hard is what it is expected to be. I can scratch either plain lead or straight COWW with my thumbnail. In the context of casting boolits "harder" is a relative term. Unless your sending it down a gun barrel at hundreds or a couple thousand fps you would not be able to tell much difference.

You have three good suggestions for your original issue of sunken ingot.

Cast by pouring into mold not melting in mold.
Cast by pouring through a cover plate with a hole, leaving a puddle on the hole that gets sucked in as the ingot cools.
Simplest - As it cools use a propane torch to melt the higher edges toward the center.

I will add one more step you could try. Use a file to smooth the bottom. File "extra" material off to get it flat then draw file it to get it smooth and polished. Don't know what draw filing is use Google, lots of videos, images, and descriptions. Be aware however that file dust, or sanding dust from lead is hazardous. You need breathing mask and to contain all dust to dispose of properly.

Or easier still cover the bottom with glued on felt so your chunk does not scratch the shelf you will have it collecting dust on.

a.squibload
06-10-2014, 04:08 AM
I don't imagine filing would produce much dust, more like chips?
Why not use the caved in side as the bottom, the cave in won't be seen.
A friend's daughter wanted some bullets to keep around the house, show
her friends, etc. He sprayed them with clear acrylic paint, no worries about
kids handling lead.
The felt is a good idea.

RogerDat
06-10-2014, 02:51 PM
I don't imagine filing would produce much dust, more like chips?
Why not use the caved in side as the bottom, the cave in won't be seen.
A friend's daughter wanted some bullets to keep around the house, show
her friends, etc. He sprayed them with clear acrylic paint, no worries about
kids handling lead.
The felt is a good idea.

Good idea on the clear acrylic paint. I might use that for any cast items I want to have for show-n-tell purposes.

Draw filing makes finer particles, probably not "dust" but fine enough to blow around or easily transfer physically. Closer to sanding waste than filing waste. Figured better to provide a caution to a person new to the process than have them unaware. If they just take a course file and make it flat enough to glue felt on the waste would be more like chips.

Frankly I think the propane torch solution is best, have used that when I booger up pouring into a mold to the point that I think it will make it hard to stack the resulting ingot. 5 seconds with a torch as it cools and it all smooths right out. Find that easier than a do over melt of that ingot since the torch is handy.

JSnover
06-10-2014, 04:14 PM
+1 on the torch. I hate filing soft metals.

konsole
06-19-2014, 08:58 PM
I stopped posting here and was going to let the thread disappear into the depths, but I discovered something about the ingots that have a sharp cave-in on the top middle of the ingot. These ingots I'm pretty sure where melted from stick-on weights so they are more pure then the other bars. I remember separating out the stick-on weights and so those 2 bars that have a significant cave-in must be from the stick-on weights. I dug a chissel into the edges of the bars and the caved-in bars certainly are softer then the bars that didnt cave-in. Plus they are darker when you look at one of the faces of the bars at an angle. The chissel dug into the caved-in bars roughly twice as far as the bars that arent caved-in.

So here is what I noticed about the difference between clip-on lead wheel weights ingots, and stick-on lead wheel weight ingots
- bars made from stick-on weights can be dented about twice as easily as bars from clip-on weights
- stick-on weight bars have a darker color when looking at a face of the bar from an angle
- stick-on weight bars have a slightly more "mirror" finish, while the clip-on weight bars have more a "silvery" brilliant finish
- stick-on weight bars seem to have a slightly smoother texture