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Casting lead milling media: mould material and media shape


deer

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Thanks Caleb,

 

I have checked out your store nermerous times. I can't make my own any cheaper then you sell them. it's more of a "can I do it?" thing. I may end up just getting them from you since i dont plan on doing large scale production i just need to fill my mill and not sure if its worth the hassle.

 

Thanks

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Getting all set up to make them correctly is the worst part. Once you are all set up the actual time it takes to make them isn't bad at all. I actually need to take a day and make some more to build my supply back up. My bucket of finished media is getting close to the bottom.

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I'm still on the fence about making my own media. I have moved on from the idea of making my own mold (lee's .490 bullet molds are quite reasonable). Does your media wear out quickly milling bp in in a pvc jar? That would be the main reason i would want to invest in casting supplies. After the initial investment subsequent casting would be a substantial cost savings compared to buying new media.

 

Thanks for all the input it's greatly appreciated

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That mostly depends on the grade of lead you're using, and how frequently you run the mill. With a hard lead like linotype or even 50:50 linotype:soft lead, the media will last for years with moderate use.

 

Many people tend to be concerned about lead wearing away and contaminating their BP, as well as wearing away the balls themselves. In my experience, it always wears away faster on the first few runs. Give it a bit before you start being concerned about excessive wear.

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Hmm. Plaster works good for few casts. Now, when the ball shrinks during cool down it sucks in a spot.

I'm suspecting this can be controlled with the pour hole somehow (like depth, width and how much i top it off)?

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Deer,

The way to handle that is in my book, "Ball Milling Theory and Practice for the Amateur Pyrotechnician".

 

It is to 'torch' the very tops of the pellets just as you begin to see them 'funneling' as they cool -- and to repeat that as often as necessary until the funneling stops.

 

This will re-melt the top enough to re-fill the cavity without re-melting the entire body, such that it won't funnel again. It will form a slight meniscus as it cools, but that won't interfere with their usefulness.

 

Lloyd

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  • 3 weeks later...

Not to get off track but you can also cast copper sleeved cylinders with no additional molds. PS< that should say "grind" instead of "gring". :P

 

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Edited by dagabu
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A warning on casting them in copper: It will eventually beat the core loose. When it does, composition will get trapped in the interstitial space, and will prohibit you from cleaning the media well enough to grind anything else (safely) except whatever has contaminated the gap.

 

It's not a prohibition on using that method, but a limitation. Add to that the cost of the copper pipe, and it just _seems_ to be more cost-effective and safer to cast the lead per se, rather than in a sleeve.

 

Permanent moulds can be made or purchased. Single-use moulds may be made from aluminum foil shaped over a dowel, and pressed down into dry sand, as a support structure. Also, long rods may be cast in foil, also, then cut up with limb-loppers into fairly flat-ended cylinders which will be beaten to "round off" nicely after just a short while of milling.

 

Lloyd

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Wouldn't it work fine to use two boards clamped together with holes drilled along the seam between them?

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A warning on casting them in copper: It will eventually beat the core loose. When it does, composition will get trapped in the interstitial space, and will prohibit you from cleaning the media well enough to grind anything else (safely) except whatever has contaminated the gap.

 

It's not a prohibition on using that method, but a limitation. Add to that the cost of the copper pipe, and it just _seems_ to be more cost-effective and safer to cast the lead per se, rather than in a sleeve.

 

Permanent moulds can be made or purchased. Single-use moulds may be made from aluminum foil shaped over a dowel, and pressed down into dry sand, as a support structure. Also, long rods may be cast in foil, also, then cut up with limb-loppers into fairly flat-ended cylinders which will be beaten to "round off" nicely after just a short while of milling.

 

Lloyd

 

If not swaged, that is true but not if pressed after they are cool. I have media out there from 2009 that has made hundreds of batches without fail. Pour-n-use is too loose in any case, swaging is the key.

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Ok... I'll agree that might be appropriate.

 

Explain how you swage the assembly -- just by 'squishing' it vertically in a press?

 

Lloyd

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I tried copper clad media that I had hammered into a dome block to round over the edges and retain the lead. It was an abysmal PITA because unless alloyed and fluxed the lead won't bond to the copper and I was afraid the gap would grow large enough to allow material to become lodged in the crevices.

The price of copper is dropping like a rock so I may try soldering caps on small lead filled sections of ½"id pipe just for giggles. Probably still wouldn't be cost effective but it's worth trying.

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  • 4 weeks later...

Just got setup with a 12 cavity aluminum mold, bottom pour melter, and 50#s of linotype ingots.

 

Takes a while to find a technique that works well, and fills the mold completely, but after a few failed attempts I'm having pretty good success. I turned out about 200 or so good, solid balls in a few hours over the weekend.

 

The nice thing is, if they dont turn out right they just go back in the pot and i try again.

 

Thanks to everyone for your help and advice.

 

Charles

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Ok... I'll agree that might be appropriate.

 

Explain how you swage the assembly -- just by 'squishing' it vertically in a press?

 

Lloyd

 

Yes, a limit block was used as well to limit the down travel so that the media wasn't crushed. The media is put under the ram and the press swages the lead to make a physical bond. EZPZ.

 

I think I have sold about 500# of them over the past 7 years, I have yet to get a response to the negative on them but I still get orders for them from others that have seem them in action. They seen to be popular with charcoal crushing.

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