635 replies to this topic

[Mortartube]

I've just caught up with this thread and seen the post about the use of coins as milling media. Just a point to any UK members who may want to try this, 2p pieces and maybe all copper coloured coins are now STEEL. Don't use them.

[EnigmaticBiker]

Here is a thread on powdering MgAl for your delectation

Thanks for the link, it is useful.
Unfortunately, the casting I'm using is too low in Mg to easily smash.
A beating with big hammer only yields 6-10mm pieces, it's a little too tough. I daren't try the coffee grinder.
I will be using your method for Bismuth/Antimony (with 2% linseed oil to reduce dust).

Edited by EnigmaticBiker, 27 October 2006 - 10:16 AM.

[Asteroid]

I'm sure they are still at least partially copper, snce with the recent rise in the price of copper, the copper in side a 2p piece is worth 3p, howevr, I don't know what date of coins this applies to

Edit:

Because of soaring metal prices in early 2006, by May of that year the pre-1992 (97% copper) coins were worth 3p each. About 2.551 billion such coins remain in circulation.

Edited by Asteroid, 27 October 2006 - 05:04 PM.

[Mortartube]

Put a magnet against a 2p piece and yopu will find it has a high steel content. All you ever wanted to know about it is here.

http://en.wikipedia...._Two_Pence_coin

[Steve]

It's the pre 1992, non magnetic ones that are worth more than their face value.

[Andrew]

This thread is straying a bit so.....


Did you know that you can make pound coins for about 30p each. I can hear everyone's brains ticking now!!!

[Steve]

To continue ploughing off topic.
http://www.telegraph...2/ixuknews.html
Puts the metal price for a pound coin at 5 pence each, seems easer than printing banknotes.

[EnigmaticBiker]

To continue ploughing off topic.
http://www.telegraph...2/ixuknews.html
Puts the metal price for a pound coin at 5 pence each, seems easer than printing banknotes.

Ah-ha, when I got some neodynium based magnets I noticed the 2ps were attracted , confused the hell out of me at the time. I ended up theorising about Cobalt content.

So, the 2.5 billion 2ps in circulation are actually worth about 50% more than face value...

[Andrew]

So, the 2.5 billion 2ps in circulation are actually worth about 50% more than face value...

Only pre 1992 (non-magnetic) ones! But you've also got to take the alloy and separate the metals to a very high purity to make your 50% yield in investment. Sounds like a lot of work to me!

Its just easier to buy raw elemental metals for the pound coin alloy and smelt them together and stamp them. Higher yield on initial investment also.

On a serious thread related note, defacing minted coinage is a criminal offence, so technically putting "older" 2p pieces into a ball mill and rounding them off if illegal!

Edited by Andrew, 29 October 2006 - 10:15 PM.

[EnigmaticBiker]

Only pre 1992 (non-magnetic) ones! But you've also got to take the alloy and separate the metals to a very high purity to make your 50% yield in investment. Sounds like a lot of work to me!

If I recall the Wiki article above, there are 2.5 billion of the non-magnetic ones.
I'd need an enormous electrolysis tank, say a swimming pool, a 5000 amp welder and few tankers of sulphuric.
Thinking of dodgy schemes, the theft of the Henry Moore was probably just extreme pyros looking for bronze mill media.
The right type of bronze would be somewhere between copper and lead shot I guess.

[hoarp001]

Hi,

Whats the best speed for a ball mill? I am using one of the inoxia white plastic jars (with the red lids) and around 1kg of ceramic media. My mill used to only rotate at 23RPM so i put a bigger motor onto it and not it goes at 53. Is 53RPM sufficiant? I found my BP from the slower mill was fairly slow, will a faster mill make a differnce?

Thanks.

[pymp]

On passfire there is a calculator that tells you the optimum speed, based on weight and size of your container/milling media, and the speed at which it becomes inefficient due to the media being forced the the sides of the jar.
I would recommend signing up to it, it's a fantastic knowledge base.

[hoarp001]

Hi,

Im s till not sure if my mill is fast enough (53 RPM)

I found this video

Clicky

Shouuld they go that fast? If so mine is waaay behind....

[Ritual33]

I think mine is about 50rpm or something, I mill my BP for a day and it's perfect, no faulting it.

Drew