64 replies to this topic

[digger]

i brought some new balls, but they where quite big. my jar is only about 20 cm in diameter and these balls were maybe 2.5 cm and weighed about 100g each. the ball mill wasn't strong enough to turn turn them reliably it kept getting stuck, i settled with six 1 cm balls and three 2.5 cm. but i didn't let this mill over night, something like 16 hours.

20cm in diameter is plenty big enough, what height is it?

OK then it is obvious that you don't have enough media in your mill jar.

Let us assume that your mill jar is 20cm in height as well as diameter. Therefore your volume is 6.2 litres so you need to occupy roughly half of this volume with media. If you were to use ceramic media to reduce the weight then the apparent bulk density is 2.15 grams per cubic centimeter (actual density 3.5 g/cm^3 multiplied by the volume fraction for spheres) therefore you will need around 1.5 kilos of media. If you were to use 2cm ceramic media these will weigh 15 grams each so you would need about 100 balls.

This proof holds true for any type of ball, hence you would need 100 balls of any type of media if they were 20mm in size for this size of jar. So if you were to use lead then (density 11.35 g/cm3) you would need 4.8Kg of media.

Obviously if you use smaller media then you will need more of them (however 15 - 20mm should be a good size for this jar). So at this size you will need in the region of 100 - 150 as previously calculated.

I suggest that you go for ceramic media if your mill can't cope with the weight of lead. But be sure to take the usual precautions such as operating the mill remotely at the end of an extension lead so you don't have to go near it when running just in case it does go boom.

Why not try these media from Inoxia CLICK ME they are not cheap, but they will do the trick.

To put it into perspective, in my metals milling jar I have around 1500 balls with a total weight of 50kg (OK this is an extreme example)

EDIT I HAVE MADE A GRAVE MISTAKE IN THE ABOVE CALCULATION I divided instead of multiplied for the media weight. It should have been 6Kg not 1.5Kg for the ceramic media or about 400 balls.

Edited by digger, 31 August 2009 - 10:16 PM.

[CCH Concepts]

this is sounding expensive, Lil. how much is 100 ceramic balls going to cost me. plus can i off set the amount of media by milling for longer periods.

[digger]

this is sounding expensive, Lil. how much is 100 ceramic balls going to cost me. plus can i off set the amount of media by milling for longer periods.

If you follow the link in the previous post you will find 1Kg is £13.50, you will need 1.5Kg (If I have guessed the correct height for your mill jar). You could get a slightly smaller jar so you only need 1kg. So not that much really. How much have you spent on chemicals to date?

No you need to have the correct amount of balls in the mill because the milling is mainly done by the balls cascading across themselves at the equator of the jar.

With the amount of media you have in your jar at the moment it would take years to make decent BP.

Come on get it sorted or give up, all the information you need is here. If you don't follow what I and others have said then don't expect to make decent BP. You may be able to make a fountain (Gerb) or two with it though.

[CCH Concepts]

sorry, just means I've been ripped off on ebay for my balls so far. i paid £5 for 10. ill be buying some more from the prices you have quoted.

[CCH Concepts]

ok just bought a 3lt jar and 1 kg of media. needed a new jar after a very stupid moment resulting in mt current just getting a little burnt.

[digger]

ok just bought a 3lt jar and 1 kg of media. needed a new jar after a very stupid moment resulting in mt current just getting a little burnt.

OK I C@cked up the calculation above (Sorry), I divided instead of multiplied for the media weight. It should have been 6Kg not 1.5Kg for the ceramic media or about 400 balls.

In the case of the 3 litre jar you would need about 3Kg of the media.

You have two options, use a 1 litre mill jar, or add 2Kg of media to the order (You would probably get away with another 1Kg but the mill will not be as efficient).

Once again sorry for the c@ck up in the calculation, I have had a few beers this afternoon / evening.

[CCH Concepts]

not a problem, im going to try with the 1 kg and if i need more by more on my next pay cheque.

[digger]

not a problem, im going to try with the 1 kg and if i need more by more on my next pay cheque.

You will certainly be much better off than you were. However a properly loaded mill makes a massive difference to its performance.

[CCH Concepts]

next question (i may need to start a new thread) if you remeber previously i spoke about a charge to fire paintbalss and i was using flash. this created quite a responce advising it was a bad idea. i was woundering if benzolift would be a good option and if so would i need to granulate it.

[digger]

I have to say, you need to get much further along in the hobby before you go back to your idea. It is like trying to engineer the San Fransisco bridge having only seen a picture of the forth bridge. You have a vast amount to learn before you will be competent to design / analyise / risk asses your device.

You will also need good meal powder to make benzolift which you don't have yet.

[CCH Concepts]

once I'm happy with my bp would this be a possibility? but current BP will lunch a 7.5g projectile about 20 or 30 feet using a 25 x 100mm tube and a tight fit. that was with 10g of BP.

[rr22]

[quote name='CCH Concepts' date='01 September 2009 - 09:24 PM' timestamp='1251836689' post='58796']
next question (i may need to start a new thread) if you remeber previously i spoke about a charge to fire paintbalss and i was using flash. this created quite a responce advising it was a bad idea. i was woundering if benzolift would be a good option and if so would i need to granulate it.
[/quote


Benzolift is in my opinion unsuitable for your paint ball claymore,
It behaves well doing what it was designed for but (again IMO) is not forgiving of confinement having
more brissance than most B.P.

I thought Pyromancer offered to mentor you on this project?

I think you would be well advised perfecting your BP and using that and your other chemicals(+books) to work toward
an understanding of the basics and enjoying your experiments at a sensible pace.

What you propose is an anti personnel device, you say "to project harmless BBs", If a prosecutor says
your ceramic media was the intended payload could you PROVE otherwise?

Pyrotechnics is a massively diverse field,I'm sure there is some other rewarding alley you could explore without exposing yourself and the"community" to this risk.

Please show some respect to the Art,and the people giving you help and advice,I'm sure they don't want you on their conscience.

Sorry if I come across as preaching at you,but your project is an accident/court case waiting to happen,and no one wants that.

Edited by rr22, 02 September 2009 - 12:20 AM.

[digger]

.....

Well said, I have run out of breath on this one.

Listen, Listen, Listen, Read, Read, Read, Patience, patience, patience, you must learn these traits CCH to survive and be successful. You are taking the very first step on the road.

[CCH Concepts]

i have gone into great details with Pyromancer and he is more than willing to help me. its a case of me being able toget down to him. the reason i posted was a spare of the moment thought about benzolift and just wanted some opionons of if used correctly with an experts help (Pyromancer for instance) would this be a more suitable propellant than flash. (im aware flash isnt a propellant, just this is as i was incorrectly using it)

[Arthur Brown]

CCH You have the services of a professional explosives consultant with massive knowledge and experience, it's really important that you actually use those services.

You clearly have a project and product in mind, but as it is nothing like a firework you really need to apply the specialist skills that have opened to you through the forum. Be very careful that the people who you consult have good skill.

As your product could be construed as an anti personnel device -even though for wargame sport, just consider that you and your product liability insurer may be standing in front of a coroner saying "I discarded the advice of my consultant and asked a few people with tag names on the net" Over this forum's short life a few people have "disappeared" after making ill advised posts that left the fireworks domain and showed leanings toward warlike equipment, DON'T be the next to disappear. There are a few explosives professionals in the members list who pop in daily yet make no posts -and that's only the names I recognise! there could be dozens and there could be more in the guests every day.