Spolette questions

[Download]

Just made my first spolettes which did not perform on a ground test anything like what I've seen in other people's videos.

 

I used green mix powder (75:15:10) that I pulverized in a blender before mixing (my non-sparking media is still in the mail). I filled my home rolled tubes (6mm ID, about 1/4") with packed them down with an aluminium rod and a small hammer. When lit they burned really slowly. It took a good twenty seconds to burn 2" and didn't burn very vigorously. Nothing like the very energetic spolettes in Gorski's videos.

 

I suspect it was the fact I used green mix, but I had thought in something tightly packed like a spolette that wouldn't matter too much. Does this sound right? As I'm still waiting for my media to arrive, does anyone have an interim solution? I was thinking wetting it into a cake, drying and then breaking it up and using the granules. I saw a video of someone using granules instead of meal, does that sound right?

 

My second issue was my home wound tubes, they seem to be shrinking. I used a 6mm aluminium rod (the same type for the rammer) but only half of the two dozen I initially rolled fit the rammer. If I tried to force it, the inside layers of the tube delaminate. I used a 50:50 mix of PVA and water for the glue. Is using different sizes for the former and rammer normal?

 

Cheers.

[Arthur]

Mixed powder is much slower than meal powder. You make a spollette with the intention of a time of burn and then adjust the amount of powder to achieve the time that you want. Very much a hand crafted product not a "cut off the roll" product. Fast powder makes short duration delays, slow powder makes longer time delays. The tube of a spollettte may very likely not be full! the powder column length is adjusted to fine tune the time.

[SKC]

One week back I made my first shell successfully with homemade spolette so just sharing my experience. First I dry rammed BP in my 4mm homemade spolette tube and noticed it was spitting fire towards shell direction at beginning of burn.

Then I added 3% dextrine with the rest of the mixture & just wetted it a little. Then made 3-4 spolettes with different length increments of BP & kept a note. The one which burnt out within 3-4 seconds was of my choice.

I made few of that in same measurement dryed them well & and all the shells bursted at apogee.

Waiting for better ideas from experts.

Thanks in advance.

[SKC]

I forgot to write that I mixed KNO3,C & S through 200mesh screen only.

[Arthur]

There is no better advice than what you did, only different! What you did worked and you chose a time for your purposes, that's all that anyone needs to do.

[kingkama]

Hand made spolettes tube are 3 turns of cardboard and 3 turns of craft paper, the inside diameter and the outside diameter are a chose of you, bigger spolettes bigger Shells, so, 6mm inside 10 mm outside are a good starting point, paper glue, wheat paste, pvb glue are equally good when well dryed. Mr Gorsky ball mill his powder for the time he need to reach a burning time of 10mm - 1second, also using your hand made powder you can tune the burning time, if ingredients are airfloat and well mixed can be used with a good result, you must to granulate with water at F4 or meal size, let dry then press in the tubes, ram rod are good in non sparking metal, i used a wood one for a lot with good results. Start with 6 mm, test the burning time and add 2mm untill you reach 3 seconds of burning time, that is the good timing for a 3 inch shell.

IMO you must read some books on BP making, before start to make spolettes, BP is the mother of pyrotechnic, fairy fountains, black match, pass fire, papers works, carbord recover in the shopping backyard are parts of the funny, don't be hasty it's a hobby not a work and remember with what are you playing with.

Search on internet there are many free books on pyrotechnic are a good start point.

PS don't blend green mix, blend ingredients by its own then mix them together with a sieve. The green mix can explode or burn fiercely if catch fire and the blender's blade are not spark proof.

Edited November 1, 2019 by kingkama

[Mumbles]

I suspect the the issue you're encountering is related to not having fine enough components. It's possible to make decent BP and spolettes without milling everything together. The next best case scenario is milling everything separately. Blenders are good for reducing particle size, but do not really get the same level of particle size as a mill. If you have any finer sieves (probably 100 mesh at least), you could try passing your materials through this first and only using what passes. I think you might be surprised at how much is retained. The nicer thing about milling the components is that it does not necessarily require non-sparking media. It's always good practice to use it of course. For instance though, milling with stainless steel still makes me feel uneasy. If I were just milling one chemical, I'd have no issues with it. Stainless steel should be non-sparking, but it just doesn't make me feel entirely at ease.

 

Everything else you're doing sounds good though. If you're having issues with tube shrinking, you can roll a few turns of clear packing tape over your mandrel and rolling over that. It gives a little more wiggle room for fitting your rammer in after they dry. Tubes do tend to shrink a bit when drying. Different glues will give different results. Generally speaking, higher solids loading and thus less water give less issues with shrinking and delaminating.

 

Wetting, granulating, and drying will probably help your current powder. It can help to break down some larger nitrate particles, and will often achieve better incorporation. A lot of people do use granulated BP for making spolettes. This has a couple benefits. Firstly, it's not uncommon to use commercial granulated powder for making spolettes. It is easy, and gives some consistency. It's of course also more expensive than making your own. On the homemade side, granulated materials keep dust down while ramming. It also tends to be more easily and consistently measured by volume. There is some thought that granulated particles tend to bite into the tube better. This is probably more applicable to pressed and corned powders than screen granulating.

[Download]

PS don't blend green mix, blend ingredients by its own then mix them together with a sieve. The green mix can explode or burn fiercely if catch fire and the blender's blade are not spark proof.

I explicitly said I blended them separately.

 

 

I suspect the the issue you're encountering is related to not having fine enough components. It's possible to make decent BP and spolettes without milling everything together. The next best case scenario is milling everything separately. Blenders are good for reducing particle size, but do not really get the same level of particle size as a mill. If you have any finer sieves (probably 100 mesh at least), you could try passing your materials through this first and only using what passes. I think you might be surprised at how much is retained. The nicer thing about milling the components is that it does not necessarily require non-sparking media. It's always good practice to use it of course. For instance though, milling with stainless steel still makes me feel uneasy. If I were just milling one chemical, I'd have no issues with it. Stainless steel should be non-sparking, but it just doesn't make me feel entirely at ease.

 

Everything else you're doing sounds good though. If you're having issues with tube shrinking, you can roll a few turns of clear packing tape over your mandrel and rolling over that. It gives a little more wiggle room for fitting your rammer in after they dry. Tubes do tend to shrink a bit when drying. Different glues will give different results. Generally speaking, higher solids loading and thus less water give less issues with shrinking and delaminating.

 

Wetting, granulating, and drying will probably help your current powder. It can help to break down some larger nitrate particles, and will often achieve better incorporation. A lot of people do use granulated BP for making spolettes. This has a couple benefits. Firstly, it's not uncommon to use commercial granulated powder for making spolettes. It is easy, and gives some consistency. It's of course also more expensive than making your own. On the homemade side, granulated materials keep dust down while ramming. It also tends to be more easily and consistently measured by volume. There is some thought that granulated particles tend to bite into the tube better. This is probably more applicable to pressed and corned powders than screen granulating.

Sieves are also still in the mail unfortunately. All I have right now is a kitchen sieve I got at the dollar store.

 

I'll give wrapping something over the mandrel a shot. I've been told paper is common? This was a problem I'd had in the past with larger rockets, but it seems to be more pronounced with the smaller tubes. There's certainly a lot less wriggle room here.

 

I'll try wetting next. Keeping the dust down sounds like a good idea too. It's definitely a problem.

Edited November 2, 2019 by Download

[BetICouldMake1]

Like mumbles said, couple turns of packing tape on your mandrel ought to enlarge it enough, and it's nice and slick. You might try rolling your spolette tubes with 3" gum tape. Spolette tubes are pretty cheap, so I usually buy them now, but I have rolled a bunch from gum tape. I figure out the length of tape I need to get the desired OD, then I roll it up on a mandrel dry with the gum side out. I make sure to roll them tight enough that they're really gripping the mandrel. I dampen the finishing edge and tube ends to lock the layers in place. Once I have a bunch rolled I steam them for a minute or so using a veggie steamer over a pot of boiling water. I like this process because you can square up the tube while rolling it since you're rolling dry, so you don't need to deal with trimming. The only downside is, since the gum side is out, they sometimes stick to one another when you steam them. But a small spray of water lets you easily separate them once they dry.

 

Dampening your bp mill dust/mix will help keep dust down but also aid consolidation and make a nice uniform grain, which is what you want. You could also rice the dust by moistening to a brown sugar type consistency with water or alcohol and running it through a screen. I wouldn't add any binder, it will just slow your burn and you're not looking to get durable grains, just something easier to scoop and pour. It's possible that wetting might improve the power since some of the KNO3 will dissolve and be absorbed by the charcoal.

 

Hotter powder makes it easier to do shorter timings, but you don't need crazy fast powder for spolettes, just consistent powder.

[Daniel1J]

Like mumbles said, couple turns of packing tape on your mandrel ought to enlarge it enough, and it's nice and slick. You might try rolling your spolette tubes with 3" gum tape. Spolette tubes are pretty cheap, so I usually buy them now, but I have rolled a bunch from gum tape. I figure out the length of tape I need to get the desired OD, then I roll it up on a mandrel dry with the gum side out. I make sure to roll them tight enough that they're really gripping the mandrel. I dampen the finishing edge and tube ends to lock the layers in place. Once I have a bunch rolled I steam them for a minute or so using a veggie steamer over a pot of boiling water. I like this process because you can square up the tube while rolling it since you're rolling dry, so you don't need to deal with trimming. The only downside is, since the gum side is out, they sometimes stick to one another when you steam them. But a small spray of water lets you easily separate them once they dry.

 

Dampening your bp mill dust/mix will help keep dust down but also aid consolidation and make a nice uniform grain, which is what you want. You could also rice the dust by moistening to a brown sugar type consistency with water or alcohol and running it through a screen. I wouldn't add any binder, it will just slow your burn and you're not looking to get durable grains, just something easier to scoop and pour. It's possible that wetting might improve the power since some of the KNO3 will dissolve and be absorbed by the charcoal.

 

Hotter powder makes it easier to do shorter timings, but you don't need crazy fast powder for spolettes, just consistent powder.

Sounds great, I'll try to do it on your advice.