How can I change the time on my spollette's? Here is what I have tried.

[Powertech]

I really like the spollette idea instead of an actual time fuse, but I could use some help.  My spollette's all burn at right about 8 seconds per inch, I'd like at least to cut that in half.  I first started with a 70/20/10, but have done 65/22.5/12.5 as well as 75/17.5/7.5.  Between the 75 and the 65 there was only maybe a 2 second difference over 2 inches.  I took the 70/20/10 and screened in some perchlorate, that only seemed to reduce the thrust which is opposite what I would have thought.  I have tried granulated and not, didn't make a difference.  I am using 5/16" ID tubes (bee nesting tubes cut to length) and test them just like Ned does in his you tube video.  My chemicals I have been using are from Skylighter, all fine powder but I milled them together each time for about 6 hours then screened them.  I'll work on uploading a video to you tube or something but any guidance would be greatly appreciated.

I guess I could try smaller diameter tubes, but the bee nesting tubes are so convenient.

Edited July 25 by Powertech

[Kalifireworks]

I dont understand, you change the time of your spolette by ramming more or less Powder. Not by modifying the powders speed

[Powertech]

But to get a small timed spollette I'd have a tiny amount of powder, which i guess may not be bad, I'm very green.

[Arthur]

Ram powder into your tube and measure the time per inch/mm then press a spollette that is the length that times right for your use. Alternatively press a long spollette  and drill a small hole into the shell end of the spollette drill carefully it's a live comp and drill exactly the right distance so that the time gets shorter by exactly the right amount.

There is no reason why a spollette from 10mm to 50mm (3/8" to 2") wouldn't work if that's the length you need to get the time you need. A large shell could need 7 - 9 seconds of flight time before bursting.

[Powertech]

Thank you!  I hadn't thought of drilling a hole to shorten the length.  At the burn rate I'll be using 1/4" to 1/2" as I won't be making anything over 3" until I'm more comfortable.

[Zumber]

Please specify more.

You want to increase timing or you need to decrease timing?

What does it mean "screened in some perchlorate" did you used few percent perchlorate?

Dont drill any holes in live mixture its too dangerous.

Edited July 26 by Zumber

[Zumber]

Just use normal 75/15/10 screened mixture for spolette and ram or press spolette of desire timing.

If you want to decrease timing then reduce amount of bp used to press spolette & if you neee more timing then increase amount of bp used to press spolette, which means if you have filled spolette half inch and you need to reduce timing then press spolette 2 mm less than half inch to reduce timing and vice versa. 

Just use a little water to moist bp mixture using atomizer spray so that composition gets pressed hard.

The empty end of spolette tube is added to shell side and filled end is towards lift charge, empty space inside spolette tube is filled with little coarse bp grain and 2 or 3 pieces of black match  is inserted in tube and wrap kraft paper around tube and tie black match to kraft paper using string.

Lift end of spolette is primed with bp slurry and bp grain or  covered using piece of black match and string.

In this way you dont need to change length or diameter of tube.

Edited July 26 by Zumber

[Powertech]

I was just afraid of using such a small amount of powder that it just blows out instead of getting a time delay.  I do use a little water and get the end rock hard and scratch a small line .  I need to get a video up

  

[Powertech]

 

[LiamPyro]

Spolette looks solid! The way I always made spolettes was using airfloat charcoal black powder, 75/15/10, milled thoroughly. An important aspect of your BP mixture is that you can produce it with consistency, batch to batch, so that you don’t have to recalibrate your length/timing ratio constantly. Faster compositions require longer powder columns, obviously, and this means that small variations in length have less of an impact on timing… thus timing can be made more precise! This would be the only reason to worry about having excessively short powder columns using slow burning comps, in my opinion. 

[Zumber]

2 hours ago, Powertech said:

I was just afraid of using such a small amount of powder that it just blows out instead of getting a time delay.  I do use a little water and get the end rock hard and scratch a small line .  I need to get a video up

  

You have not tested then properly if it burns instantly you have to add more powder and press to increase timing delay.

Only trial and error leads you toward success.

The video you posted takes too much delay. Use fast burning bp like 75/15/10.

Edited July 26 by Zumber

[Crazy Swede]

Sometimes pure black powder gives a too short column for short delay times from a practical perspective. 

There are several ways of reducing the burn rate of black powder. One is to replace 5-20 % of the potassium nitrate with barium nitrate and another is to add small amounts of inert substances that dilute the powder, like the oxides of silicon and titanium. 

[Arthur]

Make some tests using a pressed BP core of 5, 6, and 7mm thickness. If they blow through on the lift then you will have to change the tube. You only need a 3mm diameter of burning fire to pass fire to the shell burst via some quick match to get the fire to the centre of the ball instantly. Always look for the simple answer most firework makers of repute do NOT use CAD or CNC construction, but they do use simple methods with just the right amount of glue and skill.

Edited July 26 by Arthur
spling

[Powertech]

6 hours ago, Zumber said:

The video you posted takes too much delay. Use fast burning bp like 75/15/10.

This was just to test the burn rate, won't normally make them that long

 

[Powertech]

4 hours ago, Crazy Swede said:

There are several ways of reducing the burn rate of black powder. One is to replace 5-20 % of the potassium nitrate with barium nitrate

 

Edited July 26 by Powertech
I'm an idiot

[Arthur]

Press some powder into a tube, measure it, then fire it while timing it. From that you should be able to calculate the seconds of burn time per mm or other measure. From that you can determine the powder length needed to make a specific number of seconds.

[Zumber]

23 minutes ago, Powertech said:

This was just to test the burn rate, won't normally make them that long

 

Oh I see.

[Powertech]

This is about the size I may need.  0.65" of powder.  It's actually about the biggest I will need for quite awhile.

 

Edited July 26 by Powertech

[Powertech]

If anybody is looking for some cheap tubes to use, I cut these down and can get 400 spolette tubes for $13.  I guess rolling paper tubes would be cheaper, but these are by no means expensive.  I use them for bottle rockets too.

Amazon.com: Benvo 100 Pieces Mason Bee Tubes 6 Inches

Edited July 26 by Powertech

[Arthur]

If you want a short time spollette you may NEED to have a smaller diameter tube. It's EASY to wind a tube, get a set of drills from 1/8" to 3/8" and chose which one makes your best time delay. 

Just because a tube is easy to find/buy doesn't make it right.

[Kalifireworks]

On 7/26/2024 at 1:22 PM, Crazy Swede said:

Sometimes pure black powder gives a too short column for short delay times from a practical perspective. 

There are several ways of reducing the burn rate of black powder. One is to replace 5-20 % of the potassium nitrate with barium nitrate and another is to add small amounts of inert substances that dilute the powder, like the oxides of silicon and titanium. 

I have always used blackpowder and nothing else, no issues with 1cm tall colums (1 second delay). It of course also highly Depends on what you are shooting, for heavy cylinder shells you would put the spolette on top of course. One can also simply make a rather long nipple, for example a 1cm long nipple on the rammer will make a 2cm tall column but the delay of only 1cm.

 

All those massive italian or maltese meter long cylinder shells use a 1cm tall powder column in their spolettes with no issues (top fused of course)

Edited July 27 by Kalifireworks

[Zumber]

I always use Black powder for spolette with few percent titanium for white tail effect.

[Powertech]

What diameter tubes are you all using?

[LiamPyro]

1 hour ago, Powertech said:

What diameter tubes are you all using?

My go-to has always been 5/16”, but for very small shells 1/4” or even 3/16” might be more appropriate (but not necessary by any means), or tape-wrapped visco. Just be sure to prime /match the black powder surface carefully on the smaller diameters, as they have less exposed area to catch fire…

[Powertech]

I added some German Aluminum and that drastically cut down the time.  I can reliably get about 6 seconds for 2 inches now....just needed some metal.  Maybe some of my chems are not as good as advertised.

Also doesn't seem to matter if i use sodium nitrate or potassium.  Anybody ever try cesium nitrate?

Edited July 28 by Powertech