Progress on Dragon robot: Puff's Daddy gets back to me - more help - would be grand.

[rosie x]

Firstly, apologies I could not find the original thread of this discussion.

As some people may be aware I have been asking for help to build a Fire Breathing Dragon I originally saw at http://letsmakerobots.com/node/6427

The paperwork as Puff's Daddy Gareth refers to is not that obvious to me, or even others who have also read it. This prompted me to contact Gareth for more info. He kindly responded and this is his reply. I am still in the dark about the exact next steps I should take, although I think I can source what Gareth suggest in terms of purchases, the actual mechanics of how to make the Pyro tube fire is still unclear. 

If anyone "gets it" or has had experience with something similar please let me know or perhaps visit Hackerspace on Tuesday night if you have time.

Thanks in advance. Rosiex

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Hoi geekgirl (rosiex) 
  Wot....Yeah "Puff " re-kindled ..... i have to say it was a good learning 
experience. 
It would be really neat, (-: go-for-it :-) 

I guess you have already seen the posting here 
"Puff"<http://letsmakerobots.com/node/6427>which shows the mechanics 
and paperwork. 

The electronics are pretty straightforward  :- 
An Arduino with one of these motor controllers 
<http://www.adafruit.com/products/81> 
Running gear Gear motor & Tread 
<http://www.solarbotics.com/product/gmtpkg//>(although cheaper tracks are 
out there) hardest part was to secure the tracks "Tight" i wish i had 
devised some for of screw adjust to take up the slack (haha something for 
you) 
Simple ventilator fan motor (can be bought dirt cheap from supermarket)... 
this is controller via the motor controller above. 
The Pyro tube was the challenge :- hollow glass tube with a Glowplug fitted 
snug to the end (you can get glowplugs from any good model aeroplane 
shop...apply a couple of volts across it and it glows and sets light to 
"Flash Paper" (search ebay) pushed down the glass tube.......this is also 
controlled from the motor controller above. 

The fire detect part was just two photo-resisters placed in long light 
proof tubes open at the end - these where connected to 2 of the  arduinos 
analog inputs and some simple differential code worked out the direction to 
turn the head/& or the tracks. 

Thats about it ...... i has been a while since i wrote the code..... if you 
want i will dig into the archives and see if i can find it again. 

Good luck with the project .... and for sure "Beep" me anytime ... 

Best Regards Gareth 

--
rosiex
geekgirl pty ltd
po box 1216
fitzroy north
melbourne, australia 3068
mb 0423 513 452
http://card.ly/geekgirl

[Jarrod Tuma]

Ok, you have awakened the pyro in me.

Firstly, i'll try and explain the method he uses:

A glow plug is just a coil of resistive wire in a screw plug, which as mentioned, glows red hot. He then puts flash paper up against the coil, which catches fire and violently burns.

Flash paper is made by soaking paper in some chemical mixture containing an oxidiser and maybe some fuel, this means it can burn without air, thus effectively 'explodes' in a contained area (the more contained, the faster it burns and the more force this explosion will have. an open end tube simply produces a fireball) 

Black powder would be a great substitute and produces a beautiful fireball if you can find/make it, although it is probably more likely to burn down your house.. (fyi: it's pretty easy to make, safety and legality is a bit iffy though)

Both black powder and flash paper are probably going to be hard to buy legally in Australia, but the components they are made out of are common, possibly already in your garden shed. So long as you are sensible and aware of just how dangerous this stuff is, the risk can be greatly reduced. (have I scared you yet?) 

A bunch of match heads is another thing you could try.

I agree with a comment Luke made in the last thread of yours, a gas lighter type system would be easier to source parts for, safer in some ways and have no need to 'reload' between fires. A BBQ lighter could be hacked to fire using a servo, if the timing was done right, a gas/air mix could fill a tube, then fire a spark to ignite the mixture, shooting a ball of flame out the end. I'm thinking of this kind of effect: http://www.youtube.com/watch?v=eMPtSXQ17hE (if you have never done this then maybe you are not enough of a pyromaniac to take on this project :P) Maybe a device like this -> http://www.instructables.com/id/Butane-badness/?ALLSTEPS but you would need a 'richer' fuel/air mixture to get a slow burn fire ball effect rather than an explosion.

Or, forget the tube, simply spew out lots of flaming gas, flame-thrower style, this is by far the easiest approach, but also the most likely to cause a fire since it is a constant flame instead of the brief 'flash' of an ignited fuel mixture.

A spark could be made using a mechanical sparker and a servo (the same servo that fires the gas.. half pushing the trigger usually lets gas flow without a spark, then push it that last bit and the spark fires)

Can you imagine what I'm suggesting here? I could elaborate.

Please be safe, don't attempt any of this until you understand  and can control the forces at work.

Enjoy

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[rosie x]

Hi Jarrod

Wow you really are a pyro! :)

The flash paper I ordered has arrived - there was a supplier in Geelong, that Zac kindly sourced for me.

Reckon I don;t know enough yet and as Puff is made out of paper, so it all sounds rather inflammable to me.

I knew taking it on this project wouldn't be easy nor be done quickly. 

I appreciate your help - thanks so much for taking the time to reply. And yes I will be very careful.

Kind regards Rosie

[Jarrod Tuma]

Yeah I dabble, went through a rocket building stage back in high school, 6 years ago now.. still have all my fingers ;)

Great, you were able to source the paper (nitrocellulous?). That will make it all a lot easier for you. Any hobby shop will carry the glow plug you require. They are usually designed to run off a 1.5V battery, at significant current. Keep this in mind when designing the driving electronics.

Play around with small pieces of that flash paper to get a feel for it if you haven't already, make sure you have the rest in an enclosed container, safe from sparks and flying debris when lighting the small pieces, or it will all disappear in a flash and puff of smoke!!

It's probably unlikely to light paper on fire when your robot is constructed, since the flash will be so quick.

[Michael Sullivan]

Being that I am a magician I know everything about flash paper, keep it in a cool dark place as it does not need a flame to ignite it only enough heat will cause it to burst into flames.
If it is the type that comes still moist in a zip lock bag then keep it in the fridge and only dry out what you need as it us much safer and will have a longer life span.
For what you are trying to do flash wool which is like flash paper but much like cotton wool and packs in a barrel better

Michael

[rosie x]

Hey Michael

Yes the supplier explained to me to keep it moist. It is already in an air tight back but I had not thought of keeping it in the fridge. (good suggestion), which I will follow. The supplier also said you can use it for years if you look after it, and to only dry it out when needed. I will probably start to experiment with some this week. Gosh though I feel like a kid and will do so under supervision :)

Thanks for your input.

Kind regards, Rosie

[rosie x]

Highly inflammable idea;) thanks!

On 2 October 2012 17:15, Aloz1 <kno...@gmail.com> wrote:

Hi, my name's Alastair. This is my first message in the mailling list.

A quick idea comes to mind for puffs flamey breath. What you could do is use a solenoid along with lynx deoderant and some kind of small spark as an ignition source.
Just a quick suggestion.

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