38 replies to this topic

[Potassium chlorate]

I only have personal experience to guide me. I recast all of my spherical media into cylindrical media on the advice of a knowledgeable chap in the industry. I would say it has reduced my milling times by over a half and I get a better end product regarding fineness.

This is using the same mill, jar and speed.

I never tested balls, but I have cylinders with the same height as diameter and I know that my BP is much superior to that of guys who use spherical media.

[Arthur Brown]

With rock tumblers costing from £50 inc drum upwards and media from about £10 for enough for a small mill I see little need to make a lash up with anything else to do ball mill jobs.

Re the rods vs balls argument, Rods do well for handling bigger input material and fast milling down to a medium fineness. Balls will mill to much finer but don't handle large particles in the feed or do the coarse milling quickly. Also rods can tangle and bend which may ruin the whole mill, certainly need a new set of rods.

[Atom Fireworks]

I never tested balls, but I have cylinders with the same height as diameter and I know that my BP is much superior to that of guys who use spherical media.

This could be down to many factors EG, time milled, size of media, ammount of media, ammount of composition being milled, quality of chems ect... because you are not using the exact same mill and chems you can get a good enough comparison over which media is best. Mortar tube seems to have struck the nail on the head as hes done exactly that.

[whoof]

I only have personal experience to guide me. I recast all of my spherical media into cylindrical media on the advice of a knowledgeable chap in the industry. I would say it has reduced my milling times by over a half and I get a better end product regarding fineness.

This is using the same mill, jar and speed.

Can you describe how you recast please.
I have used casting rubber before but it is no good above 200 deg.
No luck with sand either.

[Atom Fireworks]

Can you describe how you recast please.
I have used casting rubber before but it is no good above 200 deg.
No luck with sand either.

Have a look on ebay for lead weight moulds, usually found in the fishing section for example http://cgi.ebay.co.u...=item20b51df3fb

[dan100]

Can you describe how you recast please.
I have used casting rubber before but it is no good above 200 deg.
No luck with sand either.

cylinders are the way forward for me aswell bp in 3 hours.
my mill works on the principals of a "roller mill" and the media is nearly as long as the jar they drop and roll uniformly as opposed to tumbling, a lot of surface area milling, after recent discussions i found that it requires uniform size feed to be most efficient all airfloat chems churns out fast bp fast but different size charcoal pieces are a job for it until they become uniform, these types of mills on a larger scale process various ore
to re-cast/cast i take copper pipe sections of appropriate size for the jar cut to the desired length
line the pipe with thin paper, block one end with masking tape and fill them with the molten lead[standing them in a plant pot helps] the cylinders should slide out, when they contract cooling and the paper should be singed ive found that if using something printed the print/carbon transfers to the media. [you can have your name on them]
alternatively if you have a press forget the paper lining pour the lead and press the ends this suage's the lead in the pipe and prevents deformation of the media.
dan.
edit: bellsofhythe make slingshot ammo moulds pricey for one set of media but multiple balls can be made quickly.

Edited by dan100, 22 June 2011 - 11:39 AM.

[jermain]

What do you use to heat the Lead up to 320 degree's? i.e hot enough to melt it?

[Atom Fireworks]

What do you use to heat the Lead up to 320 degree's? i.e hot enough to melt it?

You can easily melt lead on a bunson burner Maybe even a kitchen gas hob?

[Mortartube]

I recast my lead by melting it in a baked bean (The type you open with a tin opener NOT the ringpull type as the lip left interferes with the pouring.) I heat the tin on a camping stove (having first deformed the tin a little to make a pouring spout.) Wear eye protection and gloves and do this outside. I use long nose pliers to lift the hot tin can.

I cast my media in home rolled card tubes that I'd rolled for rockets and I plugged one end with clay, just like making a choke. Tape one end, the just put the clay in and hammer it down with a drift.

Stand the card tubes in sand or earth and pour. When set, cut off the tubes with a knife.

Job done.

You can of course roll tubes to whatever length and diameter that best suits your needs.

[jermain]

Ok thanks, I have some spare lead media, I'll give this a go. Atm I have an awful ball mill. Its a small rock tumbler that can take a max weight of around 1.5kg and so can only mill around 100g of BP at a time, to get half decent results I need to leave it going for around 12hrs. Very slow and frustrating......

Having said that I made 8 rockets on the weekend with a friend with various size differences/BP strength/nozzle sizes, ALL CATO'd. Lol good fun but a bit frustrating. Even using end burner rockets with massive nozzles (width of 1/3rd the internal diameter of the rocket) they still seemed to blow up. Made some great bangs though!

[whoof]

Even using end burner rockets with massive nozzles (width of 1/3rd the internal diameter of the rocket) they still seemed to blow up. Made some great bangs though!

Grin, no luck here yet either.

I think you have to ram them real hard.

[jermain]

Grin, no luck here yet either.

I think you have to ram them real hard.

Hmmm, are you sure? I'm pretty sure that the harder you ram them the more fuel will burn i.e. the larger the amount of pressure inside the rocket resulting in a bang rather than a rocket. The less you ram the powder the slower it should burn. I simply need to reduce the KN03 in my BP i think, it's hard with such an inconsistent crappy ball mill.

[Creepin_pyro]

.

Edited by Creepin_pyro, 20 September 2011 - 04:46 PM.

[Atom Fireworks]

Creeping pyro is right loose powder explodes due to rapid flame propeagtion and a compressed fuel grain burns as there less serface area to burn thus slowing it down. I ram them with a wooden dowel and a ram hide mallet and i give em a fair old belt on each increment.

[Mortartube]

I use one of these. A cheap price to pay for very consistent rocket motors.

http://www.axminster...ap1-prod362981/