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Discussion Starter · #1 ·
This one is a little out of the box. I picked up this WWII era Blasting Machine. I cleaned out the rust, and got it turning properly. I made this little video, where I test the current, and set off a little bit of black powder with it. My goal is eventually use it to fire my Civil War Coehorn Mortar. I thought that would be a pretty cool, and really fun use for it. Next stage of the project is to work out how to make a filament that will fit into the fuse hole for the Mortar.

 

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Just a suggestion and not even sure it would work. For filaments, maybe get some small wire guage stranded wire and unravel some and use 1 strand cut short and see if that would work. Don't know what voltage or amps your machine puts out. Frank
 

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Thought crossed my mind to try rocket engine igniters from the local hobby shop.
Not being familiar with your gear....??
 
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+1 to rocket igniters


But different principle of ignition--high temp from current versus magneto spark gap of the WW2 gizmo.

Rocket igniters go at 6V, fresh batteries. 12V from a lawn mower battery, the wire burns up to soon. But....an old Chrysler ignition ballast resistor will knock the current down.

But getting the WW2 thing to work....cool idea, let us know how it goes.
 

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You can get miles of nichrome wire for cheap, that's what we always used to ignite rocket engines, making a cannon fuse would be as simple as "Casting" the nichrome wire into epoxy or anything that would keep it from touching at the tip or shorting out on the metal of the mortar, hell, even wrapping each side in a small piece of electrical tape, or even nail polish, in a few layers,

The wire size/diameter can be sized to fit your power source, IE, a 9V transistor radio battery,(Dating myself here).

Shape it like this. For some reason, it gets hottest at the bend at the tip.

We always used micro alligator/roach clips to attach it at either side, hence the bend on each side of the bottom.

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Another thing that came to mind is the little flash bulbs that used to come with the film packs for instamatic cameras. Break the glass bulb and attach the wires and drop it down the tube and secure with tape. One shot deal unfortunately. I have an old hit and miss gasoline engine, a ford model T type coil is fed from a regular 12 volt battery and is then connected to a ground on the engine and spark plug. Supposedly puts out about enough juice to fire the plug. Frank
 

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Discussion Starter · #8 ·
Just a suggestion and not even sure it would work. For filaments, maybe get some small wire guage stranded wire and unravel some and use 1 strand cut short and see if that would work. Don't know what voltage or amps your machine puts out. Frank
That’s the direction I’m looking into. It’s been a busy week, and haven’t had time to mess with it more.

- I also saw a video of guy making starters for model rockets. - I might be about to use a thin enough gauge bridge wire and then coat it in whatever the product it for model rocket igniters to give it a boost. One of many options. The key will be to find a thin enough bridge wire made of a material to give it enough resistance.


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Discussion Starter · #9 ·
Thought crossed my mind to try rocket engine igniters from the local hobby shop.
Not being familiar with your gear....??
That’s kind of the theory, but the mortar only has a hole drilled for a fuse. A model rocket igniter won’t fit and I’d prefer not to enlarge the hole.

- I think I might be able to make my own igniter - and scale the wires down thin enough to fit with a bridge wire. Just haven’t worked it out yet, but that’s what I’m kicking around


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Discussion Starter · #11 · (Edited)
Thought crossed my mind to try rocket engine igniters from the local hobby shop.
Not being familiar with your gear....??
Actually bought a couple. Haven’t had time to mess with it yet. They won’t fit in the fuse hole, so I’ll probably have to make something, but using that principal.


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Discussion Starter · #12 · (Edited)
+1 to rocket igniters


But different principle of ignition--high temp from current versus magneto spark gap of the WW2 gizmo.

Rocket igniters go at 6V, fresh batteries. 12V from a lawn mower battery, the wire burns up to soon. But....an old Chrysler ignition ballast resistor will knock the current down.

But getting the WW2 thing to work....cool idea, let us know how it goes.
Thanks! Absolutely, my friend mentioned the Wylie coyote plunger, as a joke - and it sparked the idea for the wwii blasting machine. I’ll get it to go, just working out the details.

An actual igniter doesn’t fit, but that’s the general concept. Just need to work out the gauge and material to make a filament/ bridge wire.


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Discussion Starter · #13 ·
Another thing that came to mind is the little flash bulbs that used to come with the film packs for instamatic cameras. Break the glass bulb and attach the wires and drop it down the tube and secure with tape. One shot deal unfortunately. I have an old hit and miss gasoline engine, a ford model T type coil is fed from a regular 12 volt battery and is then connected to a ground on the engine and spark plug. Supposedly puts out about enough juice to fire the plug. Frank
That’s the general concept. I don’t think I want to track down flash bulbs... but I can make a filament, just need the right material and gauge to make the bridge wire... clever suggestion, thanks.


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Discussion Starter · #14 · (Edited)
You can get miles of nichrome wire for cheap, that's what we always used to ignite rocket engines, making a cannon fuse would be as simple as "Casting" the nichrome wire into epoxy or anything that would keep it from touching at the tip or shorting out on the metal of the mortar, hell, even wrapping each side in a small piece of electrical tape, or even nail polish, in a few layers,

The wire size/diameter can be sized to fit your power source, IE, a 9V transistor radio battery,(Dating myself here).

Shape it like this. For some reason, it gets hottest at the bend at the tip.

We always used micro alligator/roach clips to attach it at either side, hence the bend on each side of the bottom.

View attachment 3902111
That’s the general concept. Nichrome is probably the way to go, for the bridge wire. Appreciate the suggestions!


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Discussion Starter · #16 ·
As kids we used jetex fuse to ignite power charges in home made guns. However, that would defeat your objective, although it meets the 'KISS' principal - no offense intended.:whistle:
I have a huge bag of canon fuse. However, the only place I have where it can be shot, has strong fire restrictions. One of those restrictions is anything ignited by a fuse, which is to keep people from shooting fireworks.

Thus the brainstorm on how else to fire it, and not be subject to a huge fine.

- black powder muzzle loaders are allowed, which it is.


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Discussion Starter · #18 ·
Love this project.

What is the diameter of the flash hole and how deep in does the igniter need to go?
The fuse is 3.35mm. I'm gonna guess the hole is around 3.5mm. It needs to travel around an inch and a half. The barrel has an inner powder chamber to focus the charge, so it doesn't need to travel very far. The recurring response has been to use nichrome wire, and I found some on ebay for 5 bucks, so yesterday I purchased some. I'll play around with it when it shows up, and see if that makes it consistent enough. - I've found other videos about making model rocket igniters. Those also coat the bridge wire in a product that helps it burn. If my bridge wire isn't consistent enough, I'll look into either making or buying that coating product. I don't see this being difficult, I've just been busy and haven't had time to work on it.
 

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As you know the nichrome has to be just at the ignition point. How do you figure to join the nichrome wire to the conducting wire? I believe rocket ignitors use a tiny weld, like a thermocouple welder. I'm guessing the flash hole is self-cleanin and will blow out the conducting wire when it goes off. Maybe copper magnet wire to carry the current up to the nichrome?
 

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Discussion Starter · #20 ·
step one, I'll probably just twist them together to see if it works. When I work that out, I'll probably put a drop of solder on it to secure it. Simpler is better on this. I'm certainly not buying a thermocouple welder to do it. I've got a bunch of wire out in the garage, I'll pick a proper gauge of copper wire and cut it to a proper length. I'm not worried about cleaning the flash hole, If I need to clean it, I'll clean it.
 
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