First attempt on shell launch:)

[Visco]

Hey guys got another question. So I made my bp and granulated it yesterday and dried it outside in the slight sun. I'm itching to see my first she'll fly but was afraid something would go wrong(no launch, be too low of a break) so I decided to make up a mock 2" she'll and filled it with clay, no burst charge in the she'll. So I weighed it out and it wighed 35grams so I weighed out 3.5grams of bp and launched. Pretty weak and about 50ft height. I was disappointed a little and decided to try again with 4grams. Little more force taking off and if I was guessing 75 to 80 ft height. So now I have a few questions. Is it common to have to use more than 10% for lift? Is my bp too slow? Made using 75% KNO3 15% charcoal home made spruce 10% sulfur and 2% dextrin. Milled with harbor freight mill, 200 1/2 lead balls for four hours. Wetted with hot water just enough to make it stick together and still be somewhat crumbly forced through a kitchen strainer. What height should I get from a 2" she'll. It didn't seem to have the force of factory 2" shells has on launch. I'm excited that it left the tube though:) Any information is welcome. Edited September 16, 2016 by Visco

[pyrokid]

As shell size decreases toward zero, the percentage by weight of lift that you must use increases. Imaging a small cake insert weighing four grams. You wouldn't use 0.4g to lift it. I saw a commercial cake using ~2.5 g BP to lift a 0.75" comet.

 

You should test with more dummy shells until you find a satisfactory amount.

[memo]

your bp could still have moister that one day in the sun didn't dry it out, give it another day and try again. what kind of charcoal did you use ?

 

memo

[Visco]

It was homemade spruce. Will the cedar animal bedding I keep seing come up be better, I can also get as much kiln dried poplar cut offs as I can use.

 

What kind of height should I expect with a 2" shell?

Edited September 17, 2016 by Visco

[Xtreme Pyro]

My guess is it was still a bit damp, and smaller shells DO require more lift. I've used up to 5 grams on 2" shells of my hottest BP because they are so light, you should expect between 115-150 feet for a shell that size. Cedar animal bedding does works WONDERS for quality BP. If you're still not getting the power you want out of your BP.. mill it for longer. Those rock tumbler type ball mills aren't known for being the best, I'd go 6 hours or so and adjust from there as needed. Best of luck!

[Visco]

Can you reccomend a good ball mill. I have been looking at a 15 lb mill on eBay.

[chuckufarley]

http://www.woodysrocks.com/store/p94/Rebel_Upgraded_Complete_Set-Up_w%2F_35lb_Lead.html

 

Or build your own. There's lots of good info on here about ball mills.

 

Check out Lloyds book as well. Invaluable for information on ball on ball mills. Literally wrote the book on it.

[Xtreme Pyro]

Can you reccomend a good ball mill. I have been looking at a 15 lb mill on eBay.

Absolutely, I use this one myself.. Probably the same one you're speaking of. I can mill 2.5 pounds every 3-4 hours in this, makes some VERY hot BP with good quality nitrate, sulfur and charcoal.

 

http://www.ebay.com/itm/like/351622825001?lpid=82&chn=ps&ul_noapp=true

 

Then go grab yourself some milling media from Caleb.. Hard to beat his prices on that stuff, I've used it to mill hundreds of pounds of powder and they're still going strong.

 

http://www.woodysrocks.com/store/p27/10_lb_Lead_Ball_Mill_Media.html

[dynomike1]

Take your time and look around. You can scrap the stuff and build one a hole lot cheaper.

[Boophoenix]

Xtreme mentions the first idea I'd look at. If another day in the sun doesn't do it ball mill it again and re-granulate and try for full sun to dry instead of slight. If that doesn't work for you I'd look to the charcoal next and ask about your cooking process. Is it possible you may have over cooked it?

 

Caleb's modified Rebel is pretty sweet. I have a standard rebel and one of Caleb's modified ones. I recently loaned the modified out and the fella who has it is rather fond of it as well. To the point I felt it important to remind him it was a loaner setup when he was praising it, lol.

[Arthur]

Visco, you seem to be trying to optimise several variables at the same time, which usually doesn't work well.

The powder ratio is good, were the ingredients dry (warm place for 24 hours?) had the milling been long enough? Was the finished powder really dry?

 

If the powder is perfect, then ensure that the shell is a good fit in the mortar, that the mortar is long enough and that sufficient powder is used.

 

The two things that screw most first attempts are powder inadequately milled, and granulated powder still damp.

Edited September 18, 2016 by Arthur

[Visco]

Thank you for all the information everyone. Arthur you are right about trying to fix to many things at once can have an adverse effect. I will dry the powder for another day, and I made another batch with an hour more run time and I'll see if that helps any. i understand its trial and error. I'll keep working with it and let you guys know as I progress.

 

Don't know how you guys make charcoal but I just used a large metal cooker with a tight lid that had a 1/2 hole in it to vent off any steam and gas, cooked till all smoke was gone and about another 15 min past that. If you have any advice on that feel free to let me know. I'm using the search functions and reading as much information as I can. How can I tell if I have over cooked the charcoal?

[Mumbles]

In my opinion it's basically impossible to overcook the charcoal unless you are extremely negligent or are trying to do it intentionally. What you describe for cooking it sounds about perfect for a retort.

 

With a stock harbor freight mill, you'll probably need a bit more time on it. 4hr or less is on par for an optimized mill. For the slower rotation of a harbor freight, you'll probably need more like 6-8hr. Increasing the diameter of the powered roller is a common way to increase the rpms. With the stock configuration it spins around 40rpm if I recall. Ideally you want it to be around 90 when using .5" media.

 

Both of the mills mentioned already are great. The Rebel 17 is a solidly built mill, and Caleb's modifications convert it into a beast of a mill. I understand that there can be a bit of a sticker shock. I believe his modifications are documented somewhere if you are comfortable with making your own customizations. The one from hobfir is essentially built to Lloyd's specifications if I recall. I used to have one and really liked it.

[Arthur]

Remember that if you hurry pyro, it bites back. IMO drying your powder for 14 days at 5 degrees above ambient will help greatly.

[braddsn]

Visco, I have one more piece of advice for you. I learned this early on: Everyone makes bp in a slightly different way. People use different species of wood for charcoal, they cook it differently, they process it differently, and ball mills come in many shapes and forms. Add to it that KNO3 comes from different sources, as does sulfur. There are other variables as well such as mortar length, and shell clearance inside mortar. With that being said, don't worry about the 10% rule for lift. 10% is ONLY a starting point, and will get you SOMEWHAT close. Find a method to make bp as hot as you can make it, and stick with that method and don't change anything. Then, test fire shells until you get to the desired altitude, then calculate how much lift you need for your shells and you are done. Don't spend time worrying about how hot your bp is, or what percentage you are using. I know a guy who can use 4% of shell weight and reach proper altitude, and I know other guys who need 18%. It will also vary slightly depending on shell size. Smaller shells tend to use a little more lift than big ones.

 

So to summarize, 1) Make your bp as hot as you can.. in other words, use a good reactive charcoal and ball mill it properly. 2) MAKE SURE your bp is COMPLETELY dry. I use a dehydrator to take the guess work out. You may think your bp is dry, but if there is any moisture present at all, you will see a drastic decrease in performance. It MUST be dry. 3) Once your bp is correctly made, determine how much lift you need for each size shell by test firing shells, record this information, and be consistent in the way you do things. Do these 3 things and you will have tackled 1 of the many obstacles of making professional looking shells!

 

And for what it's worth, I suggest trying meal coated rice hulls (break charge) for lift. I have 2 reasons for this. 1) It is much easier to make MCRH than it is to granulate bp. 2) It tends to dry easier. I lift everything from 3" to 8" (ball shells) with MCRH.

 

Here is a 4" shell lifted with MCRH. (12% of shell weight in this case) https://youtu.be/A670_WxPCuc?t=5s

[dynomike1]

And i thought Red was bright. What size stares were those stares Brad? 1/8"?

[Visco]

Thank you brad, I've looked into the rebel 17 and think I'll go that route and purchase the high speed pulley and shaft kit Caleb makes. I'd like to have a bigger capacity mill anyways and use the harbor freight mill for milling other stuff. On the note of drying powder in a dehydrator can you tell me how long and at what temperature its dehydrated at? I picked up a couple dehydrators at a yard sale for a couple bucks a piece and would be great for that. I love this place its full of information and so far everyone has been very helpful and incouraging.

[Mumbles]

Does anyone know if you can put the Harbor Freight jars on a rebel 17 base, and if so if the speed is about right?

[braddsn]

Mike, those color changing stars ended up being 10mm before primed. Visco, as far as dehydrating, my dehydrator heats to 180 degrees. I air dry my stars for a few days until they are rock hard, then I throw em in the dehydrator for about 4 hours. They are 100% dry after that. Also drying has everything to do with humidity in your area. If it is humid, it's going to take a lot longer for them to dry, even with the dehydrator. I hate making/drying stars when humidity is 70% or higher, which is often here in the summer.

[Wiley]

As Brad and others have stated, getting the powder dry is very important. Something that I don't believe has been mentioned is how quickly the powder is dried. I personally ensure that my powder is dry within 24 hours. The longer the powder is moist, the more time potassium nitrate crystals have to grow, thereby undoing the ball mill's reduction of its particle size. This is true of any black powder-based product, including black match. I dry my match overnight, and it burns like I expect it to. In the early learning stages, I let it dry over the course of a few humid days. That match produced a good deal of slag when it burned, and it burned considerably slower than it should have.

 

I also don't believe you mentioned what size screen you used to granulate, how much dextrin was in your formula, or how you classified the powder before testing it. These are the three other paramount parameters to keep in mind when making black powder.

 

Everyone knows the difference that varying the charcoal species can have on the powder's power, so I needn't go into that. However, quite a few seem to discount dextrin's effect on black powder's burn rate. Adding between 1% and 2% to the 75:15:10 formula is about right. Any more than that and the powder's power will suffer. Indeed, simply increasing the dextrin from 1 to 2% has a measurable retarding effect on black powder made by screen-granulation.

 

For shells in the size you are describing, particle size is perhaps the most important variable once everything else has been straightened out. I granulate my powder through a 4 mesh hardware cloth, which gives me about 68% -4+8 mesh 2FA, 20% -8+15 mesh 3FA, 6% -15+30 mesh 5FA, and 6% -30 mesh fines.

 

I've made quite a few nominal 1.75" cylinder shells, some of them quite long. I use the coarse 2FA granules to lift the shells that are "longer" or "heavier" than normal. In my case, that usually means shells of 3 breaks or more. For shells "shorter" or "lighter" than that, I use the 3FA, and occasionally the fine 5FA to lift them to an appropriate height.

 

Here's a visual example:

 

A 3 break 1.75" shell lifted with 2FA at 1/16 the shell weight (6.25%)

 

 

A 6 break-and-report (1.75" nominal) lifted with 2FA at 1/16 the shell weight. The shell weighs a hair over a pound, so that's about an ounce of lift. See how much higher and faster the shell goes in spite of having proportionally the same lift as the 3 break?

 

 

Now look at what happens when a single break is lifted with 2FA. This was a 70g shell lifted with what I assumed to be a generous 6g of 2FA. As you can see, that wasn't nearly high enough. Using 6g of 3FA though, that shell breaks on the way up.

 

https://www.youtube.com/watch?v=XGPJSK7V4Ok

 

Just like when shells get longer and heavier, larger-diameter shells tend to lift comfortably with 6.25% of the shell weight in 2FA.

 

And, if you want to just "belch" a shell out of the mortar, even less than normal can be used. This was about 2% of the shell weight in 2FA.

 

https://www.youtube.com/watch?v=VEF3mLAWH68

Edited September 22, 2016 by Wiley

[Arthur]

I have a dehumidifier for when I have to dry laundry in the house, a friend has one for drying stars and powders. The warm dry air is about 10C above ambient and about 20% humidity, just feed it into a box full of damp material.

[Visco]

Thanks for all the information everyone. I dried my powder another day in direct sunlight and haven't had a chance to test again. I've ordered a rebel 17 and will try again when it gets here and I cast all my media. I figured up the revolutions per minute and realized that using the mill I should have ran the harbor freight mill for two more hours to get the same time as the rebel with upgraded pulley kit. I think the main thing was the time it was in the media. As a side note the animal bedding everyone is talking about is the aromatic red cedar correct? If so I'm doing some fencing and have been pulling a pile of these things out of the old fence on the farm. May try making a batch out of these posts. I'll let everyone know how it goes when I get a chance to try again this weekend. You guys sure do make some beautiful shells.

[Wiley]

Yep, aromatic red cedar pet bedding. I get my bales from Walmart now that Lowes decided to stop carrying it. Cook up half to a whole bale in a TLUD (or an array of three little ones if you're me) in an afternoon and have enough charcoal to make a good bit of powder. I get about 30g of coal per gallon of shavings.

[Visco]

I have a question about the rebel 17 I ordered? I was reading about it and was wondering all the information I have red says it has a 17 lb limit. And I just got to thinking! The media will weigh over 17 lb. Will it handle 25-30 lb of media or am I automatically going to have to upgrade the motor before I can use it?

[Arthur]

Overloading a mill makes it likely to stall, probably a good reason why not to use a rock tumbler. Underfilling a mill makes it slower to get to desired particle size. Sometimes it's a choice, sometimes it's a compromise. If the mill takes two drums, assume it will only turn one drum full of led media. This is why some people use ceramic media, the balls are lighter so you can get more in before the stall.