some of my latest bits

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Dalemartin
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Joined: Mon Aug 29, 2016 2:38 pm

some of my latest bits

Post by Dalemartin »

hi guys hers a hand full of vids of mine and my friends latest bits,any tips or advice welcome

2" shell
https://www.youtube.com/watch?v=Pj1JyuJ ... EeUMKSgpxA

300mm wheel 1"x4" Ti spark gerb drivers
https://www.youtube.com/watch?v=c4DkPjs ... xA&index=3

1"x4" Ti spark gerb
https://www.youtube.com/watch?v=1U-bWPw ... EeUMKSgpxA

1/2" core burner test Ti spark
https://www.youtube.com/watch?v=LMVNl1h ... xA&index=1

let me know if the links work as there set to privet
i have a photo of the un fired wheel but im not sure how to post it on hear ?
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richardh08
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Re: some of my latest bits

Post by richardh08 »

I can't see any of those videos. That's probably because they are private. Perhaps you need to change their status.

To include an image, drop down below the input text window for your post and click on 'Browse'. Locate the name of the file you want to include and click on 'Add the file'. Then, if you wish, you can also click on the 'Place inline' button, which positions it at the current cursor position in your text.
Even when I'm wrong, I'm convincing.
Dalemartin
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Joined: Mon Aug 29, 2016 2:38 pm

Re: some of my latest bits

Post by Dalemartin »

thanks for that i have changed them to unlisted
300mm wheel fineshed1.jpg
300mm wheel fineshed1.jpg
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Dalemartin
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Re: some of my latest bits

Post by Dalemartin »

ooops the photo is huge
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Boophoenix
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Re: some of my latest bits

Post by Boophoenix »

Nice stuff Dale. Have ya ever tried bumping the gerbs? Just Incase you've not heard the term a tiny increment of BP is pressed as the last increment to clean the tube abruptly. It changes the end sligly and clearly marks the end. Notice I said tiny it can also cause a CATO if over done.

I have the same problem pretty often uploading pics. I finally broke down and went searching for an image editor to adjust the size via pixels to fit on the page better.
Dalemartin
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Re: some of my latest bits

Post by Dalemartin »

Hi Boophoenix I herd the term "bounce" but from the description I read it sounded more like self destruct lol so I left it alone, but how you describe it sounds interesting I'll give that a try,
I have 12" girandola in the pipe line but I'm waiting on a friend to contact a farmer he knows about using a space to fly it before I build any drivers for it , I've just built the frame so far
Dalemartin
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Re: some of my latest bits

Post by Dalemartin »

Thanks for looking BTW
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Boophoenix
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Re: some of my latest bits

Post by Boophoenix »

Not the best example, but this was from my early early days of getting involved. I believe it was a cone fountain, but the same principles apply.

https://youtu.be/0V09mwPlG2w

While the fountain wasn't much pumpkin the bump was about right. This one was a 1/2" ( 13mm ) tube. Done with homemade tooling made of Al and a wood block. It was a challenge with a cordless drill that drilled straighter than the drill press at a friends, and I could see the wobble in the cordless.

https://youtu.be/gNHgd4wna7s
Dalemartin
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Re: some of my latest bits

Post by Dalemartin »

Ah yeah see what you mean I like them mate the second one still looked as
Good as any from a selection box .how do you press/ram a proper cone do you need multiple size rammers ?
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Boophoenix
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Re: some of my latest bits

Post by Boophoenix »

Dale, I just usd the largest dowel rod I had at the time and worked my way around the comp the best I recall. Slightly moist comps should consolidate fairly well this way. They won't be as good as a good pressed comp, but they'll work
Dalemartin
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Re: some of my latest bits

Post by Dalemartin »

Thanks I'll give it a go, I have a textile spool That has a thick wall
sambo
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Re: some of my latest bits

Post by sambo »

Nice one Dale,
Good stuff and really enjoyed the vids !
Just be careful you're not ramming comps with rather high metal content ?
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Boophoenix
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Re: some of my latest bits

Post by Boophoenix »

Good point Sambo. Thank ya. I'm think I just tamped mine in with the dowel, but there are still issues with metals there too.
Dalemartin
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Re: some of my latest bits

Post by Dalemartin »

yes i hand rammed them or rather taped them
26% Ti the same as Ned G used

i did it out doors wearing a full face shield welding gloves and welding sleeves,
BUT your right it is a little risky so i will be investing in an arbor press soon.
I'm a welder faby by trade so i could build a 4 post frame to extend the range,

i have a question if you could help me out pleas
im a little confused about star/gerb formulas that use Al and Kno3
as i know to never make flash with them as it can become unstable,
so... is it the mesh size of the Al that makes the difference?
as a larger mesh has less surface area
the formulas i have seen don't include boric acid and use water as the solvent

id rather ask and be safe

cheers
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Boophoenix
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Re: some of my latest bits

Post by Boophoenix »

Dale, as I'm still fairly much a newbie still I'll give your question a go, but I may get corrected.

In regards to sensitivity and Aluminum ( Al ) most of that is going to take place with fine mesh flake. I have read some about some really really fine atomized being used, but you'd almost have to special order that. I've tested -325 and while not physically reactive n the since it will flash super bright eventually with enough heat. Fine magnalium ( MgAl ) when really fine can be reactive as well.

Now more inline with your question the ratio's should not be in a range to be reactive in the since you are asking when used the n gerb and fountain formulas. You'll have to use your better judgement on where you get your formulas as that could render the previous statement false. I don't believe KNO3 is as reactive with Al n the since of flash either ( guessing a little ).

It's not that flash is unstable really it's just very sensitive and doesn't react well with mistakes or oopsies. Keep in mind many of the things we use can have reactions especially if you don't practice good cleaning up practices. The dusts drift around and accumulate even if you don't notice.

I've not experianced any adverse reactions from formulas that give you the option of adding boric acid or not, but I do include it if the formula outright calls for it. I may have a reaction the next formula I mix though.

A personal thought of mine and I Try to be careful of this many a times we're tinkering with things we're exposing ourselves
to a fuel/air reaction should a spark or flame be introduced. I don't worry endlessly about that, but I do keep it in my mind.

I'm sure someone will step in soon and give some more details or corrections if I need them. :-)
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richardh08
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Re: some of my latest bits

Post by richardh08 »

What Bradley says is pretty much on the button. A mixture of pure potassium nitrate and aluminium isn’t chemically unstable, but its speed of burning will be greater if you use materials with a smaller particle size. However, it can be unstable if other substances are present.

One chemical test for a nitrate is to add the substance in question to a solution of an alkali, such as sodium hydroxide. You then add a little powdered aluminium and, if necessary, warm the solution. The unmistakeable smell of ammonia indicates that a nitrate is present.

Commercial grades of potassium nitrate contain impurities, some of which could be alkalis. Also, since charcoal is usually somewhat alkaline, any mixture containing a nitrate, charcoal and aluminium – such as a glitter composition – could, in principle, react in this way once water is added. How likely it is to happen depends on a number of factors, including just how much alkali is present, the size and shape of the aluminium particles, how much water you add and whether you dry the mixture under heat. Atomised aluminium mainly consists of roughly spherical particles, which offer a relatively small surface area, but flake aluminium has a much larger surface area – particularly if the particle size is small – and is much more likely to react. The danger is that much greater in a large batch, where the heat generated by the reaction can’t escape so easily.

Some people always add a little boric acid to this type of mixture, regardless of whether it is or isn’t listed in the formula, and some don’t. I can’t make a recommendation either way, as the actual level of risk can vary widely, depending on both the composition and the exact nature of the substances you use. Most charcoals aren’t that alkaline, so the risk is generally not that great, but I wouldn’t be entirely comfortable if I were using dark pyro aluminium.

However, as with any potentially hazardous undertaking, you need to be aware of the risks and make your own decision on how you deal with them.
Even when I'm wrong, I'm convincing.
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Boophoenix
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Re: some of my latest bits

Post by Boophoenix »

Thank ya Richard I learned something new even without a correction, lol.
Dalemartin
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Re: some of my latest bits

Post by Dalemartin »

hay thanks guys

that has helped

the reason i asked and believed it to be hazardous is that i read a thread on (i think it was)
Pyro society uk, a Noobe started a post about his flash using kn and Al
those that replied said that kn Al should not be mixed and to come back after learning why
in that tread it mentioned some thing about the Al pulling oxygen from the nitrate and heating up
(maybe when wet )

if i can fined it ill post a link

and my friend read about old skool photo flash that was kn al and was mixed on site and used in a short amount of time and never stored

that is what put me off using it till i new more

i have 5kg bucket of coarse aluminum used in a casting process i brought for gerbs



thanks for that i feel more at ease with those star comps
Tyvole
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Re: some of my latest bits

Post by Tyvole »

Hi Dale, welcome to the forum. I don't have much experience with this, but.. I did have a minor issue once with Granite stars (Zinc, PotNit) using a water-based binder. The mix got pretty hot and scared me - I just spread it out some to allow the heat to escape better and kept mixing. I got away with it and the stars worked just fine but it's not an experience I want to repeat. I don't remember now if there was a smell of ammonia, it was a few years ago. So, next time, still not having any boric acid, I substituted for a different binder that used acetone as the solvent. No issues. I now assume that, unless a couple of percent boric acid is added to the water, a similar nasty reaction can occur with pretty much any finely divided metal when mixed with a nitrate and water. Having said that, I have read that while this is ok with 50/50 MgAl it is NOT done when using pure Mg. Someone more educated may be able to explain why not...

Nice videos, btw. Thanks for sharing them.
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Dalemartin
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Re: some of my latest bits

Post by Dalemartin »

Hi thanks for that I did a little reading on wiki about
Old photo flash and pure mg was used and only mixed on site and never stored
As a mixture. But in contradiction to what I had read else were
It says that amateurs Often use kn and al

I will have to re watch Ned Gorski's gerb
Vid again as I'm sure he mentioned about it
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