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#21 OldMarine

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Posted 21 February 2017 - 07:34 PM

Alloying the metal is pretty straightforward and not hard, Take respiratory precautions and be sure you wash your hands before sucking your fingers but otherwise just get the lead plenty hot and stir your antimony in with a metal rod while tossing in sawdust and beeswax to keep the top fluxed. You'll see when the metals alloy and then you add more sawdust and wax and stir for a few more minutes then done!


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#22 chuckufarley

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Posted 21 February 2017 - 07:44 PM

Thanks everyone. I've only done it once with pre-alloyed Linotype. I've just been thinking about setting up a few more jars for milling other chems, without having to clean the contaminated media between runs. Having a cheap supply of pure lead handy got me thinking about alloying my own (thinking again) so I thought Id ask. If I do it I think Id get the pre-alloyed 30% antimony/70% lead ingots and mix with pure lead accordingly. I could make up about 20 lbs of 10% antimony lead with one 5lb bar or super hard alloy and 15lbs of soft lead. For $20 or so it might be worth a try.

#23 otto

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Posted 21 February 2017 - 08:40 PM

I think if you talk to the guys manufacturing commercial amounts of 1/2" media you'll find they use 50/50 lead to linotype which would produce lead with 6% antimony which is hard enough.  I used 100% linotype (12% antimony) when I made my media and its very hard and puts a lot of undue stress on your mold and is miserable to cut the sprues off the ball but produces excellent media. Pure antimony can be added to molten lead but takes a certain amount of flux and must be done at about 600 degrees for good results.  A process probably best left for a smelter.  That's the reason people use linotype or other "type set" metal for the antimony content,  the alloying work is already done for you .  I can tell you after pouring and cutting off sprues for 100 lbs of media my hands cramped up and hurt for about a week (I'm an old guy).  It was a fun learning experience but I'll never do it again.  After you consider your time, materials,  blisters and lead spills on the garage porch floor,  you'll find the price these guys charge on the forum and elsewhere for the finished product a real deal and worth every penny!   Kurt

 

I've cast lead fishing jigs/sinkers for decades. Not difficult, but proper tools help a lot. When I got the bug to cast my own media I already had a .50 cal mold for round balls. I poked around a little bit and discovered there's a few "levels" of type alloys that are available.

 

Linotype, despite its reputation as a hard alloy, is the softest and most available. Increasing in hardness and scarcity are monotype and then foundry type. I bought into a pile of foundry type and cast my media straight, exploiting the superior hardness without dilution. As a result I didn't feel the need to quench though the finished product would certainly have been even harder. Out of the mold the hardness made the cast so brittle sprues snapped off very cleanly when fresh. Once cooled even a bit they were almost impossible to snap much less cut. My media is very satisfactory and will likely last as long as I want to use it. I guess we'll see....

 

There's also a tradeoff in media. You can't have maximum mass AND maximum hardness. As your lead alloy increases in hardness those very additions make the alloy less dense piece for piece. I don't have a calculation for hardness vs mass in a grinding media but I'll bet there is a tipping point and I don't know where that might be. It's probably dependent on what you're grinding and how far you want to take it.

 

Casting your own isn't difficult and can keep you in media as long as you've got raw material.



#24 lloyd

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Posted 21 February 2017 - 08:50 PM

"I don't have a calculation for hardness vs mass in a grinding media but I'll bet there is a tipping point and I don't know where that might be."

---------------

I don't either, Otto, but I'm betting it makes no difference.  The reason I say that is that the next less dense medium would be steel (stainless steel), and that's VERY much less-dense than any lead alloy you could think of.

 

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#25 calebkessinger

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Posted 22 February 2017 - 07:54 AM

Oh the joys of casting lead..

 

Wheel weights..  yak they are down to almost 50% trash..
lead from flashing.  not bad , but big and dirty

I get my lead off of ebay in precast ignots now.  I get an already hard blend. and then add linotype to it. 

I've poured straight lino,  and used foundry.  Both I didn't like and didn't get my moneys worth in both stress and tool wear.

I can get 1000 lbs of media out of a mold now which is acceptable.  I have my eye on an automatic caster at the moment.   It's hard to drop lead and run machines at the same time.  :) 

I do water drop mine/  dry them,  and fill a mill jar up darn near full and then run them overnight to clean them up.  Then I pick out all the oddball/ junk i can find. 

It's work , but I have a pretty good system now after running 5 or 6 thousand lbs of it. 

 

I believe united nuclear gets mine.. and some other guys as well. 

Once you get clean materials and a nice groove it's not too bad of work.. The first couple 1000 lbs really really sucked as I figured it out.  :)


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#26 otto

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Posted 23 February 2017 - 05:45 AM

Yep. Lead ain't what it used to be.... I've got a pretty good pile of soft and foundry waiting for reuse. Precast ingots are a crap shoot. Might have zinc mixed in among other stuff. Unless you're tight with your supply you'll never know until you melt it down.

 

I don't do the kind of volume you do Caleb so sacrificing a mold here and there doesn't hurt so much. I'm currently considering casting lead cylpebs in a home brew mold. Not hard to make and easy to replicate.



#27 dynomike1

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Posted 23 February 2017 - 05:46 PM

Is there any reason you couldn't use Zinc?


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#28 lloyd

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Posted 23 February 2017 - 06:19 PM

1) You'd lose the density advantage of using lead. (look up their relative densities)

2) Zinc is a pretty active fuel, and not desirable as an additive to most color comps.  For BP... I don't know.

 

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#29 dynomike1

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Posted 24 February 2017 - 07:09 AM

What i am finding is the specific gravity of Zinc is less than Lead, but more than Ceramic. What i was thinking that there might  be a contamination problem with Zinc since it seemed like everyone was dodgen it.


There are very few problems that cant be solved with explosives.

                             Explosives are a bang up job.


#30 passgas

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Posted 05 March 2017 - 09:38 AM

This is what I am doing . I am smelting wheelweights and  adding 1.5 to 2 percent zinc. While still molten in my pot I will stir in some Zep rootkiller . This is suppose to change it into a hard lead/copper compound. Go to CastBoolits and do a search for Zep rootkiller. This is all new to me so I will do a 10# test batch and cast. If it works I may do another test batch and try raising the zinc percentage 1 to 2 percent. If it fails I just do the old fashion way and buy some linotype/wheelweight mixture. I will cast plain wheelweights to compare against. I will be casting 60 cal balls. Still waiting on my mold to come in. By the end of the next week I should get something going.



#31 MrB

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Posted 06 March 2017 - 06:10 AM

Why would you add zinc, just to then add rootkiller, and try/hope the sulfur parts of it burns of the zinc? At least that is what i think they are trying to do. Also, they use it as a copper medium for plating a copper "jacket" on to the bullets. At which point you got a copper contamination problem, and shouldn't use the copper coated milling media for fireworks.

Lead is good since it doesn't affect the fireworks effects. Copper is bad, since it's used to color shit in the sky, among other things. At that rate, casting lead in to copper pipe, and cutting it up is a better choice, at least the copper is think enough to be structural. Brings a whole different issue with lead working it self lose, and so om, but...

 

Anyway... Don't intentionally ruin lead by adding zinc to it.

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Edited by MrB, 06 March 2017 - 06:10 AM.


#32 MB3

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Posted 14 March 2017 - 06:39 AM

I use Alumina ceramic cylinders 1 pack of 13/16 $16 and 1 pack of 1/2 $7 from pyrocreations.com I mix the 2 togeather and its enough to fill 2, 3lb mill jars more the half way. In 4 hours they make very fast bp I have tried alot of diffrent media types and these are by far the best I have found. the only down side is they make the ball mill run a little louder and rougher but its well worth it

#33 lloyd

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Posted 14 March 2017 - 08:02 AM

"I mix the 2 togeather..."

---

<sigh>

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#34 MrB

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Posted 14 March 2017 - 12:05 PM

As far as i can understand, he's using the same supplier, and 2 different sizes. It should be "safe" if either media can be considered safe to start with. They have similar optimal RPM, even if not identical, due to having the same density.

What are your objections?

 

I have no idea, hence asking. I've read recommendations for using different size media as a means to speed up the milling, where people claim it's more efficient, but it's countered by the claim that the smaller media will wear faster. Never really tested either claim, but faster wear seams... logical. And if the wear accelerates, the same effect should actually make for faster milling as well, so it sort of makes sense, i guess.

B!



#35 a2l

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Posted 16 March 2017 - 06:38 AM

I've got a small question but there's no need to make a new thread.

I've got a 1.5L (0.4 gallons) drum which I'm looking to buy lead media for. The diameter of the jar is just shy of 6".

Now I'm a bit torn on what size balls to buy. I know Lloyd recommended at least 1/2", but up to 1" would work as well. Yet more balls means more grinding, and lead is the heaviest media so I guess the ideal size is more towards 1/2"?

What are your thoughts?



#36 OldMarine

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Posted 16 March 2017 - 06:46 AM

I use ½" hardened lead in my 6" mill jar as well as in my larger one and achieve excellent results. Dave Forster has used smaller stainless media with good results but it requires longer milling times.
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#37 a2l

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Posted 16 March 2017 - 07:13 AM

Thanks. And between 1/2" or 11/16", which would be the better one?

Hmm maybe I'm getting too hung up on this minor issue.



#38 OldMarine

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Posted 16 March 2017 - 09:47 AM

The ½" hardened lead is the gold standard and though Lloyd could give a more informed answer,I think anything larger would reduce milling efficiency due to larger spaces between the balls.
That said, I was just reading of a fellow with a 24" mill who uses billiard balls for milling charcoal. I think the media size is related to jar size but not sure how.
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#39 lloyd

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Posted 16 March 2017 - 09:56 AM

"...I think anything larger would reduce milling efficiency due to larger spaces between the balls."

-0-

This is a hard one to explain to some folks.  With smaller media, the spaces are smaller, but there are more of them, and the total amount of open space in the mass of balls remains the same, regardless of their size.  It is approximately 60% solid, 40% open space.

 

The smaller media mills more efficiently (when each ball is heavy-enough to give the desired impacts), not because of the smaller space, but because there are more contact-points in a mass of small balls than in a mass of large ones.

 

As an extreme example, take a 6" i.d. mill, and put TWO 3" lead balls in there.  There will be but one contact point between the two.

 

LLoyd


Edited by lloyd, 16 March 2017 - 11:06 AM.

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#40 a2l

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Posted 16 March 2017 - 11:00 AM

Then it's settled, thanks guys.





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