635 replies to this topic

[Creepin_pyro]

I hope you have a VERY long extention lead and a nice deep hole to bury that mill in!

That's a lot of BP - stay green!

[EnigmaticBiker]

Hi friends,

I told my Al-foil-milling-story before and here is another result:

I sieved the resulting powder a,d found that approx

25% are bigger than 50 mesh

25% are bigger than 150 mesh and

25% are bigger than 325 mesh.

The fourth 25% are -325 mesh.

I dont have a sieve finer than 325 mesh but I hope the -325 mesh fraction will be good enough for flash. The particles will be very flat flake shape so the chance is quite good.

MfG
newtoolsmith

That's a useful spread of particle sizes and in flake form too.

I haven't milled metals yet I need to get some accurate mesh and try milling some magnalium (engine casing, so 5-10 Mg I guess). It is fairly brittle so should mill well.

Your mill is elaborate and impressive, looks really well built. I could do with a decent DC power supply like that for mine.

[Andrew]

at a rough estimate, 1kg at a decent speed.

Could do up to 1kg if it was given enough time. Using Lead instead of ceramic would speed things up a little, as it is 3 time more dence than ceramic. Still at optimum speed you can only realistically get 400g per 3L of milling jar volume. You can get more at the expence of time in the mill. It is inportant to not clog up the mill; if too much is put in the mill will not be very efficient at all.

My 3L mill makes 400g of good quality bp in a little under an hour (with ceramic media), 3 hours and it produces a flour like consistancy. From experimentation I found that just adding an extra 100g takes the mill time up to over 4 hours; four times longer is not that optimum. In that four hours I can make 1.5kg rather than one batch of 500g.

[newtoolsmith]

@EnigmaticBiker:

I remilled the coarsest particles (+50mesh) and the yield of the -325 fraction is some bigger now.

The -50+150mesh will be used for rockets to give a nice tail. This is not tested yet because I had to do other things (look at the Perchlorate thread).

Some days ago I made a few kg MgAl - it was very easy - and I milled it after crushing it into pieces.

I didnt sieve the resulting powder yet but I guess nothing is over 50mesh, only a little -50+150mesh and most will be -325mesh.

I dont have a sieve finer than 325mesh but I hope it will be fine enough for flash.

MfG
newtoolsmith

[Ritual33]

I just got myself the CR2 tumbler from MM with 2 700g rubber jars, also another 1.4kg jar is arriving when it's in stock. I have to say I didn't expect this thing to be so quiet, Richard; do you use rubber jars with your mill or do you use plastic ones?

Regards,
Drew

[Richard H]

I use the rubber ones half filled with 1/2" by 1/2" brass round bar as media.

[Ritual33]

It seems to run a tad slow, is this normal and if so have you done anything to speed yours up? Do you not find that there's alot of spillage around where the rubber O ring sits? Everytime I open the barrel I spill a bit of BP and have to clean it. Apart from this it's a very good tumbler indeed, thanks for recommending it Richard.

Regards,
Drew

[shadowpyro]

I ordered the exact same rock tumbler actually, though i ordered the plastic container instead- simply because i already have a rubber one from a previous tumbler. havent been able to mill anything yet as my ceramic media still havent arrived from inoxia yet.
Do you know whether theres much difference in the plsatic ones compared to the rubber ones? (i found that the plastic ones will require rubber bands for grips and they tend to slip when a heavier load is put in)

[EnigmaticBiker]

Is the sound insulation effective? Mine is LOUD!

I managed to quieten my mill a little very easily, a 100mm thick foam block underneath it really reduced the sound transmission.

newtoolsmith:-

Glad you've had some success.

MgAl is amazingly easy to mill, I milled some engine casing shavings this week and it milled to below 100 mesh in 12 hours (with 5% linseed oil). I dried it over gentle heat (~100deg.C) and it burns beautifully bright in a fountain.

Unfortunately, making small enough chips to mill, using a drill and rotary rasp, is very time consuming.

I'm currently trying to work out an efficient method for milling PVC and Sulphur, the elastic properties of both don't help.

[fishy1]

I managed to quieten my mill a little very easily, a 100mm thick foam block underneath it really reduced the sound transmission.

newtoolsmith:-

Glad you've had some success.

MgAl is amazingly easy to mill, I milled some engine casing shavings this week and it milled to below 100 mesh in 12 hours (with 5% linseed oil). I dried it over gentle heat (~100deg.C) and it burns beautifully bright in a fountain.

Unfortunately, making small enough chips to mill, using a drill and rotary rasp, is very time consuming.

I'm currently trying to work out an efficient method for milling PVC and Sulphur, the elastic properties of both don't help.

Is your magnalium 50/50? I'd never be able to get shavings off mine, just too brittle.

[Ritual33]

The rubber barrels on the Cr2 slowly travel to the side of the rollers that the metal side is facing, this happens on all of my rubber barrels so I think it's normal. Also they leak around the O ring seal just inside of the barrel. I'm wondering if the plastic barrels will do this as they seem quite symetrical in shape. If somebody could tell me that the plastic barrels do not slip without rubber bands I'll buy a few of them as I'm not bothered about noise.

Regards,
Drew

I ordered the exact same rock tumbler actually, though i ordered the plastic container instead- simply because i already have a rubber one from a previous tumbler. havent been able to mill anything yet as my ceramic media still havent arrived from inoxia yet.
Do you know whether theres much difference in the plsatic ones compared to the rubber ones? (i found that the plastic ones will require rubber bands for grips and they tend to slip when a heavier load is put in)

[myinisjap]

"Ball milling media for pocket change. Here's a tip for all those pyro types that mill their own black powder. Much has been discussed about using a non-sparking media, and whether or not ceramic balls will cause an explosion, possible health problems from lead media, etc.



I've been using good ole U.S. of A currency discs for that purpose for the last five years with nary a problem. The nickel and quarter denominations work very well. They don't spark; They are about impossible to wear out, and they're cheap. I use 12 quarters and 20 nickels to mill 100 grams of lift in about 3 hours. The coins cascade in landslide fashion down the inside the tumbler and provide a shearing/rolling action to the mix.



I mill the charcoal and potassium nitrate for 2 hours and add the sulfur for the last hour. After pressing, corning, and screening, my lift BP is as good as any commercial product I've tried. My milling tumbler is an ancient '70s model Thumblers Tumbler with a rubber jar of about 3 pounds capacity. It is soooo-- old I had to replace the jar and sealing ring last month, the motor let go about 1986 and I replaced it with a continuous duty rated fan motor which continues to grind on and on.





And here’s yet another variation on charcoal sparks from Flint Hapirat for all ye tropical pyromaniacs. Thankee, Flint."
article



I was wondering if this would work? or should I just use brass?

[Ritual33]

Better safe than sorry mate, I use ceramic myself, If I could source some nice lead ones I would snap them up .

[EnigmaticBiker]

Is your magnalium 50/50? I'd never be able to get shavings off mine, just too brittle.

It is in the region of 10-15% Mg as far as my investigations have uncovered, pretty typical of the alloys used in engine casings (injection casting I believe) of the time.

It is brittle and breaks pretty easily with a small hammer (even easier in a crash ) but only down to 1cm pieces, so I drill it. Love to know an easy way of processing it.

Good for fountains etc. but have decent commercial grade for demanding applications.

PM me if you want some to compare!

[RegimentalPyro]

Love to know an easy way of processing it.

Here is a thread on powdering MgAl for your delectation