My homemade black powder

[Vettepilot]

It seems like everyone struggles to quite meet the density of commercial powder, and the only possible variable I can think of would be the charcoal itself.

If anyone knows for sure, or even has a logical guess, let us know! It's a curiosity.

Vettepilot

[Super Sneaky Steve]

I was able to form my double stuff Oreo cookies today. The cheap-o press did the job. It's slow going with such a small die but it should provide me with many more hours of fun.

I put the pucks into my dehydrator. Max temp was about 180f in my garage which is 39F at the moment. Nothing blew up! They were in there for about 5 hours. I don't trust it to run while I sleep. I'll probably still give it a week before I try to break them up.

[Agent1187]

Has there been a consensus about what to expect on screened powder density? I feel like that should be a pretty consistent (albeit low) density without the differences in compression like pucks.

My last batch came in at a whopping 56% of standard - a 100 grain volumetric measure scaled out at 56 grains.

[Eddie2002]

Agent1187 you need to take 100 grains by volume of a commercial powder and weigh it then compare that weight/volume to your screened weight/volume. 100 grains by volume of commercial powders doesn't weigh a full 100 grains by weight.
To answer you question my screened powder weighs 65% of the commercial brands so to shoot a 65 grain charge I measure 100 grains of home made.

[maillemaker]

I had stored up an entire peanut butter jar full of green meal (plus fines from the first batch of puck grinding) so I did some more puck pressing tonight:





I've got the dehydrator going on the back porch. It's 26F outside now, but the pucks are registering 120F - 130F by infrared thermometer after cooking about 10 minutes.

I did a little test to see how volatile damp green meal is. I put a smidge on a piece of sheet metal and took it outside and hit it with a lighter. It went POOF! Very little difference between damp green meal and dry green meal.

I have to say I'm having second thoughts on the safety of puck pressing. I'm using an aluminum tray and the aluminum puck die and piston, and plastic dividers. But once the green meal is constrained inside the puck - that is a bomb casing. And supposedly BP can be set off by friction. I'm probably over-worrying this but seeing how easily damp green meal burned off in a flash gives me pause.

I'm giving serious thought to integrating an electric hydraulic motor into the Harbor Freight press to make it electrically actuated with a pressure shut-off. This would enable remote pressing of pucks.

Steve

[RoyEllis]

Yep, you're worrying too much. As long as you keep ferrous metal away from the powder (so no sparks) you'll be fine. At least I haven't had a problem in over 50yrs of doing this.

[maillemaker]

It seems like everyone struggles to quite meet the density of commercial powder, and the only possible variable I can think of would be the charcoal itself.

It may be a time under pressure variable also. I hold my pucks under pressure for 5 minutes. I don't know how long commercial mills run the powder under pressure.

Yep, you're worrying too much. As long as you keep ferrous metal away from the powder (so no sparks) you'll be fine. At least I haven't had a problem in over 50yrs of doing this.

Good to hear, Roy, thanks!

Steve

[Eddie2002]

I just weighed 100 grains by volume of Grafs 3f and it came out at 102 grains by weight. Didn't have any 2F handy but I think it would be less dense. So for reference 3F powder is pretty close to the marked weight on a measure. Checked my screened powder and it's at 65% with large grains.

[SeaMonkey]

I hold my pucks under pressure for 5 minutes. I don't know how long commercial mills run the powder under pressure.

Link to Firearms History Blogspot article about Pressing Black Powder

A pressure between 375 to 450 pounds per square inch is applied, according to the fineness of the powder,
the amount of moisture it contains, the humidity of the atmosphere etc. The compression process lasts
about 30 to 40 minutes. The work is done slowly and the pressure is eased off and re-applied several times,
in order to get greater density without applying excessive pressures. As it happens, the edges of the cake are
always less compressed than the middle, because the powder layer can fall away around the edges. Therefore,
the sides of the cakes were cut off at about 1inch thickness on each edge and the center sections were used for
further processing.

The ideal average density for cakes produced by this process was somewhere between 1.7 and 1.8. The pressed
cakes were then taken to the next stage of the process, granulation

It would seem that if the Pressing is done incrementally and repeated a sufficient number of times that enormous
pressures are not actually required. Of course this process relates to the period of early hydraulic presses and the
more modern techniques may require more pressure to speed the process up.

It seems that releasing and reapplying the pressure during the pressing may be an important function though.

[maillemaker]

Interesting quote, SeaMonkey!

I think our cakes, being constrained in a piston and bore, are probably uniformly pressed.

But it is interesting that their compression process lasts 30-40 minutes, albeit with lower pressure.

I think on my next batch I will increase the compression time to 10 minutes and see if it affects the density.

BTW, that link contains numerous fascinating articles on the period manufacture of black powder! There were a lot of steps involved that we are omitting! Glazing is said to slightly increase the density of the powder. Since we are not glazing the powder, this might be why our powders are slightly less dense. Note that glazing did not necessarily mean using graphite.

Steve

[LynC2]

Interesting quote, SeaMonkey!

I think our cakes, being constrained in a piston and bore, are probably uniformly pressed.

But it is interesting that their compression process lasts 30-40 minutes, albeit with lower pressure.

I think on my next batch I will increase the compression time to 10 minutes and see if it affects the density.

BTW, that link contains numerous fascinating articles on the period manufacture of black powder! There were a lot of steps involved that we are omitting! Glazing is said to slightly increase the density of the powder. Since we are not glazing the powder, this might be why our powders are slightly less dense. Note that glazing did not necessarily mean using graphite.

Steve

I had been thinking the same thing. The glazing process rounds off the sharp edges of the powder grains and I believe that allows a greater amount to fill the same volume as our homemade powders.

[maillemaker]

So I had previously 3D printed an adapter that would let me replace the glass jar of the ceramic coffee grinder with an adapter that let me mount a piece of PVC pipe to the bottom of the grinder head. But I still needed to figure out how to mount the thing. So far I have been holding the grinder in one hand and turning the crank in the other which was difficult at best. As an old engineer once told me, "If you don't hold your work your work will work you."

So I had an epiphany and redesigned the adapter to have a mounting flange:





This works fantastic. Now I have the grinder mounted to a block of wood with a large hole cut in it, and the grinder stays put so I can easily grind up puck chunks. This is 1000 times easier than before and makes puck chunk grinding way faster than before.

I am going to have to get serious about doing all powder work outdoors, however. It is obvious that any powder processing, especially sifting, produces lots of black powder dust. And even when doing things like grinding or puck busting there is always the errant bit that goes flying. I have been working in my workshop while learning this process but already the dust is a problem and I am having to clean carefully to as not to end up with a buildup of explosive dust in my work area that at best could result in a flash fire but at worst could set off other powder and things I have in my shop.

[Vettepilot]

What? You didn't want to jigsaw a hole in your work bench for it??



That's cool!! Wish I was into 3d printing, but NO!! Got too many projects and too much STUFF now!!

Vettepilot
PS-> I had mentioned about polished powder likely stacking tighter together a good number of posts back...

[square butte]

maillemaker - Any chance we might twist your arm and get you to print up some of the adapters with mounting flange for folks who might be interested - at a healthy profit of course ? ?

[maillemaker]

Looks like someone has one here: https://www.shapeways.com/product/43...li=marketplace

[Vettepilot]

I like your design better.

Vettepilot

[Super Sneaky Steve]

I had stored up an entire peanut butter jar full of green meal (plus fines from the first batch of puck grinding) so I did some more puck pressing tonight:

I've got the dehydrator going on the back porch. It's 26F outside now, but the pucks are registering 120F - 130F by infrared thermometer after cooking about 10 minutes.

I did a little test to see how volatile damp green meal is. I put a smidge on a piece of sheet metal and took it outside and hit it with a lighter. It went POOF! Very little difference between damp green meal and dry green meal.

I have to say I'm having second thoughts on the safety of puck pressing. I'm using an aluminum tray and the aluminum puck die and piston, and plastic dividers. But once the green meal is constrained inside the puck - that is a bomb casing. And supposedly BP can be set off by friction. I'm probably over-worrying this but seeing how easily damp green meal burned off in a flash gives me pause.

I'm giving serious thought to integrating an electric hydraulic motor into the Harbor Freight press to make it electrically actuated with a pressure shut-off. This would enable remote pressing of pucks.

Steve

I'm using that same dehydrator. I don't think you have much to worry about when pucking. There's no oxygen in there. I did mine with a stainless steel die just going slow. I'm tempted to try and light a puck on fire to see what it does but I don't want to waste that much right now.

How long did you run your dehydrator for? I'm not sure how dry these pucks need to be.

[square butte]

I like your design better.

Vettepilot

Yep - Yours is better

[Vettepilot]

Yep - Yours is better

Yeah, Maillemaker's is more secure AND easier to mount, and it doesn't have provision to keep the glass jar in place which we neither need nor want...

Vettepilot

[Vettepilot]

I'm using that same dehydrator. I don't think you have much to worry about when pucking. There's no oxygen in there. I did mine with a stainless steel die just going slow. I'm tempted to try and light a puck on fire to see what it does but I don't want to waste that much right now.

How long did you run your dehydrator for? I'm not sure how dry these pucks need to be.

Just to be clear here, Black Powder doesn't need air/oxygen to ignite. The KNO3 is the oxidizer, and thus BP has it's own built in oxygen.

Having said that, I still don't think puck pressing nor dehydration of the pucks is especially dangerous if normal precautions are observed.

IF all prudent precautions are taken, I feel the DUST is the greatest hazard.

Vettepilot