16 replies to this topic

[Farnet]

Hi all,

Just before I disappeared off the face of the earth a few years ago (actually got a job in london and spent my life living in crappy B&B's during the week, and in Central London they are crappy), I saw a thread about who could make the best BP for use in propelling a tennis ball the furtherest using a cannon.

I found this fantastic and after reading about Balsa Charcoal being the best I decided to make my own. Well I think I did too well as the stuff is SOO light I really am having issues weighing it.

When I made the first batch there seemed a hugely disproportionate amount of charcoal to Saltpetre and Sulfer. Anyway I continued and when actually trying it I was extremely disappointing (I used the basic mix rather than granulating it, as I'm still learning, and haven't got that far yet), well it was very slow and it was quite obvious that a lot of the charcoal hadn't burnt as there was a huge amount of residue left on the floor, and if anything the residue seemed larger than the original mix .

I'm using jewellers scales that are acurate to 0.1g and retried the mixes, but the same happened.

It there something fundemental that I'm doing wrong? or is my charcoal just too fine (if that is possible) ?

I have just received some willow charcoal and it is so much denser than my homemade stuff so I will retry the basics again this weekend with that.

I still have a huge amount of balsa powder left, it's stored in a glass jar and after shaking it briefly, it really does act like a liquid, interesting in it's own right but frustrating at the same time.

Farnet

[Farnet]

Before any of you say it, I should have tried the basic stuff first, but I was very interested in making my own charcoal at the time, and I always have the opinion, if you are going to do it, do it to the best of your ability.

I am pround of my charcoal, but not how it reacts as a component, I do think I should have wet the mix and used dextrin, but this was 3 years ago, either way, I shouldn't have been left with such a huge amount of residue... and that is what bothers me.

BTW whatever happened to that thread, as it was a really good piece, and most people were rising to the challenge, as well as creating rules and measurement, I did learn a lot from it.

[megabusa]

Are you mixing the BP in a ball mill ?

[Farnet]

Are you mixing the BP in a ball mill ?

No, and I'm coming to the conclusion that it is probably my mixing, as I don't think that KN03 had bound properly to the charcoal. even with best intentions doing it manually was painstaking and ineffective....

Ohh well, as I mentioned in another post this morning, I should have the makings of a ball mill at home waiting for me tonight :-)

[Arthur Brown]

Some of the Americans who post on USA based forums say Balsa is good for fast charcoal. However before you commit yourself to your batch please get the basics of the process right.

[Algenco]

Balsa is excellent, Pawlonia is a little better.
I make Pawlownia charcoal and thought the same thing, it is so light and fluffy.

You need to use a ball mill, the stuff will be so fast it will scare you!!

Someone else said " the bigger the kilo(charcoal), the faster the powder will be

[pyrotechnist]

I have seen balsa bp that was just a simple green mix burn very fast so not sure what may be happening with your comp. I know this sounds stupid but could your scale batteries be going causing inaccurate calculations. Another charcoal that is good is cork charcoal though its a pain due to its spongy nature even when cooked and lightness.

[Farnet]

I'll set them up and run some tests... have some very accurate weights that will give me a result.

Went down to the shed to start setting up for the weekend and found that the entire inside is saturated, with water dripping off the electrics.

One dehumidifyer later, heyho.

I'm really looking forward to retrying those tests now I have a firmer knowledge of what I am trying to achieve. so watch this space.

[pyrotechnist]

Also try using CIA method with the BP though over fuel it! as quite a bit of charcoal is lost on filtration which degrades performance of the powder. If the balsa still doesnt work then I really am not sure what is wrong with it.

[MDH]

If it is not burning fast, then it is the charcoal that is at fault. I have made straight, unmeasured, unmilled and crude powders out of balsa that still burned like a well milled pine...

[Pyro.1]

i agree that the balsa bp green mix should be quite fast too, maybe the OP has some moisture in his chems if his scales are reading fine.
it sounds like his workshop is damp prone.


Paul.

[Farnet]

lol, when I did the test the shed was rather new and VERY dry and it was in the summer, all the chems were brand new from inoxia, all apart from the charcoal.

I do think I wasn't hitting the target due to inexperience and being over excited at making my very own charcoal....sad I know but true.

As for the shed, well I have 1x60 litre/day and 1x28 litre/day dehumidifyers going (its an 18ft by 9ft shed) and things are starting to dry out, so I will be on track for next weekend, hoping I get the orders from inoxia and ebay on time.

[Deano 1]

You say you've made this charcoal yourself, is it possible you've over cooked it and your actually using ash. Balsa is that light and I don't think it would take much air to burn it through when you think its cooling down. How did you make your charcoal?

[Farnet]

I don't think it was over cooked as there would be a very noticable colour change, the charcoal when taken out of the improvised oven was jet black, hard 'ish' but very light.

I crushed it in a pestel and mortar, and mashed it to an extreme fine powder, I must admit I starting to change colour myself by the end of it and I literally had to hose myself down before being allowed back into the house.

overcooking, or allowing oxygen into the container would have spontaniously ignited the charcoal and the edges would have turned a grey colour so I am very confident that that didn't happen as I allowed to oven to go cold before I opened the lid.

[megabusa]

The green mix should be quite fast if the chems are fine enough. BUT, for example, If the KNO3 is like salt it won't be that fast.

You will see a massive change in BP quality when you start using a ball mill with decent media. It grinds all the chems properly & mixes them well.

I used to make good 1" ID rockets with the chems ground by hand. When I got a ball mill with lead media I had loads of CATOs. I had to adjust my ratios, nozzle size & even tube strengths to get them to work again.

My normal BP (using BBQ charcoal) that I now use for lift is way faster then my hand mixed BP used to be with commercial A/F charcoal.

It all take lots of practice, many failures & then when you get it right, you think its so easy !!!

Phil.