Lead casting

[Chris1274]

Hi guys,

Does anyone have experience with casting lead? I'd like to make specifically shaped lead weights for some freight cars and I'm not sure what the proper method is for making molds. I tried searching around on google but didn't find much of anything helpful for what I have in mind. Thanks in advance,

Chris

[Lemosteam]

I would not use anu material that cannot handle 600+ degrees.

I have used hi temp silicone (with a solid master, repeat castings are possible), JB Weld mixed with craft sand (with a lost-wax master, repeat castings are possible), real clay, (with a solid master, no repeat).

Talc in the mold helps to smooth out the surface of the hot metal.

As always, caution with lead is paramount, not just being molten but the resuidue left on the hands,  wash often.

I have since made a silicone mold of the finished casting (post machining) in a silicone mold.

[Chris1274]

That's perfect, exactly the sort of instructional I was looking for 

[randgust]

Micro-Mark has T160 bismuth alloy, a whole lot less toxic, easy to mold, easy to make weights with.   I pour it into conventional rubber molds and those have outlasted any of the regular resin molds by years.   My 'masters' are laminated-up styrene cut to fit, use those to make the molds.  Some of them are actually pretty complex.



I hammer and trim soft lead for one-offs.  I don't saw it, you don't want that dust.  I trim it with flush cutters.   Fishing sinkers are my best source of small bits.

[Cajonpassfan]

Randy, how heavy is the Bismuth alloy?
Thanks, Otto K.

[peteski]

I hammer and trim soft lead for one-offs.  I don't saw it, you don't want that dust.  I trim it with flush cutters.   Fishing sinkers are my best source of small bits.

And I used to play with unpainted lead solders when I was a kid...

Lead is so soft that there doesn't seem to be any dust while you saw or file it.  The metal is too heavy, and shavings are way too large to get airborne.  Even sanding generates rather coarse powder.  But I guess one can't be too careful. 

[Scottl]

Well, all I will say is that there are health risks for melting down lead of unknown source and purity.  Metal vapors are nasty stuff, and fishing weights are usually poorly refined. If you want to do this, I strongly recommend doing it outside.

[randgust]

Randy, how heavy is the Bismuth alloy?
Thanks, Otto K.

It's heavy.   I consider it a fully acceptable substitute for lead.   I think it had a predecessor; "Cerro Bend", back in the day.

Oh, and I've never, ever, ever melted lead.  I do melt the T160 in a steel ladle over a butane torch and pour that way.   It melts at 160 degrees.  Lead melts at what... 621 degrees?    What's astounded me about it is that you can pour it into a resin part and it won't melt it - it will soften it, but it gets along amazingly well.  I've made hybrid parts with some parts of resin and some of metal in the same molds.

[BobRunty]

And I used to play with unpainted lead solders when I was a kid...

Lead is so soft that there doesn't seem to be any dust while you saw or file it.  The metal is too heavy, and shavings are way too large to get airborne.  Even sanding generates rather coarse powder.  But I guess one can't be too careful. 

I was gonna say something similar, Peteski. My friend had some soldier molds when we were kids and we would melt down lead and make our own. Ahh the things they use to sell for us adventurous young-uns.

Bob

[jdcolombo]

And I used to play with unpainted lead solders when I was a kid...

Lead is so soft that there doesn't seem to be any dust while you saw or file it.  The metal is too heavy, and shavings are way too large to get airborne.  Even sanding generates rather coarse powder.  But I guess one can't be too careful. 

I think the right advice with respect to lead is "be sensible."  Wash your hands after handling the metal; don't put your fingers in your mouth with a bunch of lead dust on them.  Clean up your work area after handling it (brush any bits into a wastebasket, vacuum up any dust).  I do agree that if you are melting it, do it in a well-ventilated area.  I've used lead in modeling for 20+ years and I don't have lead poisoning.  Lead shouldn't be anywhere near children (in paint, or any other form), but for sensible adults, it's not exactly like handling plutonium.

John C.

[mmagliaro]

You can get a wide variety of bismuth alloy ingots with lower melting points here:
http://www.rotometals.com/product-p/lmp158.htm   (158 degrees F alloy ingot).

My calculations on the 212 degree stuff work out to a density of 9.53 gm/cc

(Amazon.com has those ingots listed with a size of 2.2" x 2.2" x 0.6" and a weight of 1 lb,
so I converted inches to cm, and lb to gm, and computed the density).

That compares to pure lead with a density of 11.3 gm/cc
So while bismuth alloy is pretty good, you are definitely giving up some weight compared to lead.

[Cajonpassfan]

Thanks for taking the time to do this Max!
Otto

[peteski]

I think the right advice with respect to lead is "be sensible." 

It is amazing just how much sensibility and common sense are lacking in today's world. 

I have melted lead and I use sheet lead flashing as weight for N scale cars.  I cut, saw and file lead but I don't go licking my finger afterwards. I have also used electronic solder (both at work and for hobbies) for decades. It also has lead in it. I'm still alive with no signs of lead poisoning. 

[C855B]

Pikers. You guys never worked around hot lead typography - Linotype and Monotype line casters, slug extruders, and other (in today's nanny society) truly scary stuff. We had to do things like skim the dross off the lead pots, especially in the remelt room where we cast the ingots that fed the casters. Adequate ventilation? Phooey! At least the remelt room had a big fan.

OTOH, the two earliest print shops in my career are or were Superfund sites. Nothing to do with the lead, tho' - one was because we did chrome plating of printing plates, the other due to the accumulated solvents. It was a dangerous world only about 30 years ago, at least as defined by today's overwrought standards. (Tell us how you really feel, Mike.)

[nkalanaga]

Pure metallic lead isn't all that toxic.  Lead compounds are very toxic if they are easily vaporized, soluble in water, or can be digested.  And, if your lead isn't pure, it can other heavy metals in it, many of which are more easily absorbed and.or more toxic than lead.

Lead tire weights are fairly safe, as they're meant to be used outdoors, and can't dissolve or corrode, or they wouldn't stay in balance.