19 replies to this topic

[Ferret]

I didn't intend to get back into pyro, but it's too late now, I've been back in the shop making things again.

 

I've become more obsessed with getting my BP perfect this time around, and I've heard the topic of storage containers come up somewhere. On some forum, can't remember where I was reading it, a poster was raving that tin quart cans were the perfect storage container for black powder. Like the way Goex used to come in, although now I always see it being sold in plastic containers. What are your preferences? 

 

Is there a safety component to this? Obviously a tin can would provide a nice air-tight seal, but so does plastic. The only benefit I can see is that the conductivity of a tin can would disperse static charges better than plastic which can hold static charges, but then again BP is not sensitive to static unless that involves a static discharge aka spark. One disadvantage of tin can storage would be possible rusting in humid climates. 

 

 

 

On a second note, I got some graphite powder from my other hobby of high power rocketry, leftover from machining nozzles. I've heard of coating BP with graphite in a star roller, anyone ever tried that for hobby use before? About how much graphite to BP is a good ratio? It's totally unnecessary for sure but thought I might try it out and see if it really improves the pour-ability of BP at all. 

 

I know these aren't very riveting questions, but the forums look a bit slow so I thought I'd ask a few questions here and there. 

[justvisiting]

First, the BP is tumbled by itself to knock off the sharp edges and round the grains, and the fines are sifted out. Then it is tumbled with maybe 2% of fine graphite powder, and any excess is sifted out. I tried to eliminate the first step. I failed to get good coating because the BP that came off the edges mixed with the graphite. Next time I'll follow instructions instead of trying to cut corners.

I'm corning pucks right now, I'll try it again and see how I make out. My graphite is from the farm supply, used for lubricating the tracks in seeding equipment. I think this might be a coarser grade that may not be ideal for our purpose.

[Ferret]

Ahh, did not know of the first step, that is helpful to know. So it sounds like the process will break some grains and make more fines, which is frustrating. It already seems like when I grind my pucks I get about 30-40% back in meal D grade, which I will just end up re-pressing into pucks 

 

I have two theories on the excessive meal dust problem - one is that the grains need to be drier, perhaps more days in the drier even though I already wait two days before breaking pucks. I may need to do "the ziploc bag" test for moisture content. The other theory involves the binder itself. I use commercial dextrin at 3% wetted with 10% by weight 75/25 water/alcohol. I have suspected that either Dextrin itself is proving to be a so-so binder, or perhaps that the 25% alcohol is not getting the comp wet enough to activate the binder. 

 

I also grind my pucks with a mortar and pestle, although I plan to make an automated puck crusher eventually. I suspect that hand-grinding may generate more fines since it is a more random process - I dump the mortar when it just "looks ground enough", which could be ground too fine in reality. What process do you use to break your pucks? 

[justvisiting]

The pucks I am making are pressed up to about 4T force, on a 2" diameter puck. I press them 1/2" thick, to a density of about 1.8. They are dense and very hard, and clink like china when smacked together. I have been using 8% water to dampen, as per Kyle Kepley (Passfire). I'm currently doing tests to evaluate the effects of 8, 4, 2, and 0% moisture on the pressing of pucks to commercial BP density. I'll have a report in a week or two.

 

Pressing pucks to this density, regardless of the moisture used, makes them pretty hard to break up (corn). I do this to make black powder that can be directly compared to commercial black powder, not because it's necessary to puck black powder to make a usable product. The consistency achieved by using this method makes it useful for comparing powders to each other.

 

To break and grade my pucks, I use a Louisville Slugger with the end of an aluminum meat hammer affixed to the end of the bat. I put a puck in a plastic test cap, lower a loose-fitting sleeve into the cap, and run the bat up and down inside to break up the pucks, which are screened through 4 mesh. What rests on the 4 mesh is returned for more crushing and re-screened, etc.... With proper technique, I get about 2/3 2FA grade, and 1/3 mixed finer grains and dust. The dust is the smallest percentage of the whole. Again, I do this for testing purposes- not for production purposes. I say all this because I think you need to make powder this way to have a product that can be processed into shiny, slippery grains (not that it's needed).  I hope I've included enough disclaimers to save anyone saying I don't 'need' to do all that work

[Crazy Swede]

Why do you want to tumble and glaze your homemade black powder?

It will reduce its ignitability and slow down the surface propagation, i.e. you will experience it as inferior compared to the raw product!

[Ferret]

Yeah, I know glazing will slow it down a bit since it is basically "diluting" the BP. It is more out of curiosity than necessity. I think I would compare glazed BP to unglazed after I did it to see just how much it slows it down. 

 

I also use BP in my muzzle-loading replica pistol, so of course I am used to seeing glazed goex going into the bore when I load it. So another reason I wanted to do it was to make a BP "like goex", volume-measurable, so I can use a powder measure instead of weighing grains. I have been using the density calculator on Passfire as well to get my BP presses as close to 1.7 as I can. Basically my goal is a standardized powder with repeatable results. I only produce a few pounds per year, even when I was at my highest output year I probably only made five pounds, so everything I do is more "experimental" rather than production. 

 

justvisiting, I'm not sure I understand your puck breaking process fully. What do you mean by the plastic test cap? Does the puck get crushed inside a plastic box? I take it you are basically breaking the pucks with a baseball bat inside a bucket? 

 

I pressed one puck with no water for a test, it produced a puck as hard as all the others although it did not make the sharp clinking noise when struck like wet-pressed pucks do, when I crushed it it seemed to break into powder even easier than a water-bound puck. I'd be curious to see what your results would be. I know 10% seems excessive since water ends up leeching out the bottom of the puck press anyway. I bet I'm getting too much meal dust from not waiting for the pucks to dry long enough. Next batch I will give it a week or so before grinding. 

[justvisiting]

Ferret, the plastic test cap is made of LDPE, so it's flexible and won't break from the impacts, and the shards of puck digging at it. My baseball bat with the square meat tenderizer hammer head mounted into the end of it is raised and brought down hard on the puck, inside of a 3" ID ABS pipe about 18" long. Confining the BP this way assures that each hit does work, and no chips fly out of the tube.

 

I've got it down to a repeatable process that gives very consistent results. The grade I use for baseball testing is 2FA, and I am personally surprised that my redneck 'corning equipment' gives me very close to 2/3 2FA every time. I give a few hard whacks to break the puck up, screen through 4 mesh, return what sits on the screen to the tube using a large funnel with a large mouth (the top of a water jug), repeat, repeat, repeat, etc... As the amount of BP getting crushed gets less and less, I use less muscle to break it up. Before I get to the last bit of a puck, I'm introducing the next one, so I'm not beating on a few grains and crushing them to a finer grade than I desire. For the grade you want, you'll probably use more muscle and less screenings. The more 'sessions' of crushing and screening, the more consistent the result.

 

What I do to get consistent density is to use a puck die that has a 'stop' on it. The sleeve is bronze 'oilite', and the 'plunger' is aluminum, made for me by Woody's. It has a head on it that stops the plunger at 1/2" puck thickness. It was made, taking into account the pressing base that goes into the bottom of the sleeve to press against. The base goes 1/4" up into the sleeve. Each puck is pressed to exactly 1/2" thickness this way- although, there is a slight amount of expansion when the pressure is released- maybe .002 or .003".

 

When I press single 2" diameter X 1/2"  thick pucks, I use about 4 tons of force. The force is increased slowly, with some dwell between cranks on the hand-cranked hydraulic pump. Once the stop bottoms out on the sleeve, my puck is at the right thickness. It takes 3-5 minutes to make each puck. The density is controlled by the weight of powder used for each puck, with water considered as an additional percentage to that.

 

Kyle's use of 10% water is certainly excessive for MY application. It should be kept in mind that Kyle is pressing multiple pucks at one time for general (pyro) use, and that the large amount of water is being used to facilitate that. My process is for test pucks, and would lend itself to firearm use (I think), because it makes (potentially) more consistent powder. 

 

I tried to press a puck using no water at all, just dry powder. I aborted after raising the force to 7 tons, almost double what I normally use. The resulting 'puck' crumbled upon ejection. The function of water in the production of black powder was shown to me in a very obvious way. Also, your observation that breaking up damp pucks makes more fines coincides with my experience. 

I don't want to comment at this time on what percentage of water (I think) is ideal for single pucks until all my testing is done. Working on it now.

[justvisiting]

I did more work making pucks and testing powders. Baseball flight times of 6 batches of powder were compared, and varying percentages of moisture were used for pucking to evaluate differences in pressing and performance. I wrote up a report of my findings for anybody that's interested. It's here:

http://pyrobin.com/f...ix ways V.2.pdf

[justvisiting]

Tumbled for 2 hours to round off  the grains, sifted the fines out, wiped out the jar, re-tumbled for an hour with a pinch of graphite (1.5%). It was too much, so I tumbled again for 15 minutes with a few pieces of paper towel to take up the excess graphite. I gave a couple of SHORT bursts of Static Guard when tumbling with the graphite, just because. Worked pretty well, I think.

[Maserface]

That looks good enough to eat

[dagabu]

Nice!

[Ferret]

Wow, that is some good looking BP for sure! Im guessing that is 2FA? Have you compared 2FA to 3FA? Ive been usuing 3FA for 3" shells and it works okay, i sometimes wonder if 2FA is too coarse for smaller mortars/wastes powder. As in powder is still burning after the shell has already left the tube

Great attention to detail it seems you have, im impressed

Just read the report, it looks like you did compare 2FA to 3FA (1fg), 3FA does have a slightly longer flight time, which I suspected. Probably also harder on the shell too, but no flowerpots so far for me

Edited by Ferret, 03 April 2019 - 05:46 PM.

[Mumbles]

I actually prefer 4FA for smaller shells, under a pound or so. It's a convenient cut size if you're making 2FA as well. 2FA has been inconsistent for me in those sized shells.

[Wiley]

Yep, finer for smaller shells, as Mumbles says. I like -8+12 for 3" and 4" single breaks, and switch to -4+8 for 5" single and bigger. I used to think that I needed to go to -3+4 for 8" shells around 25-30lb, but found that they often struggled on the way up. I now use -4+8 for those and they lift the way I like. The coarse -3+4 works great for 50lb up to 100lb so far.

Edited by Wiley, 07 April 2019 - 10:41 AM.

[ChrisPer]

Hi All! This is my first post here. 

Just made a lot of tools and  created my first batch using garden shop 'soil conditioning' charcoal. Pretty average. 

 

I wish to contribute an idea to the pressing of pucks.

 

Thin pucks will break up more easily and dry faster.  However, less than 10-13mm per puck makes it a very long job. So I put dividers in the puck - cut from a strong plastic bag, 50mm dia sheet plastic disks every 5mm or so thickness of puck. No need to be perfectly flat but each time I hand push the material down in the cylinder with the piston, then add a disk, then scoop in more dampened meal, repeat 8 times or so.

 

So I pressed about 40-50 mm column of dampened meal at once, which I split apart when I get it out, so the 5-8 mm thin pucks dry more easily and crush without herculean effort.

Edited by ChrisPer, 20 January 2021 - 03:20 AM.

[Arthur]

With no evidence whatever I've always wondered what the effect of a non flat puck would be. If a puck was domed, concave side down when pressed, would it be better or easier to corn to a useful product, and particle size range.

[justvisiting]

That's a great idea Arthur! other shapes might be useful too, like maybe a die that makes a cross-hatched puck.

[ChrisPer]

I weighed my products. I got about 50% fines  when I broke the thin pucks by busting them in a bag with a rubber mallet on concrete floor, and sieving and busting until all was 20 mesh or less. Very wasteful. This is also the kind of number you get in a quarry, crushing roadbase.

 

Skylighter mentions busting pucks a bit while they are moist.

 

I have only done my first batch though, still got a lot to improve.  My aim is to make a substitute for commercial 3F and 2F for muzzleloading.

Edited by ChrisPer, 20 January 2021 - 10:30 PM.

[Arthur]

For small users I'd suspect it's worth having corning methods that produce a usable distribution of grain sizes. I've used two different meshes for making wet powder.

[kingkama]

I weighed my products. I got about 50% fines  when I broke the thin pucks by busting them in a bag with a rubber mallet on concrete floor, and sieving and busting until all was 20 mesh or less. Very wasteful. This is also the kind of number you get in a quarry, crushing roadbase.
 
Skylighter mentions busting pucks a bit while they are moist.
 
I have only done my first batch though, still got a lot to improve.  My aim is to make a substitute for commercial 3F and 2F for muzzleloading.

if you want to make gun powder, you need to make a different blend than the classic 75.15.10 this mix Will produce a lot of waste Which over time destroy the rifle, so the compositions are different 78 12 8 Is a good start.