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Author Topic: My first mortar - and first post, and a few beginner Q's  (Read 927 times)

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Offline bloomautomatic

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My first mortar - and first post, and a few beginner Q's
« on: March 16, 2006, 06:11:12 AM »
As if I don't have enough projects, I had to go and browse this board and see the little micro-mini mortars.  Here's a pic of my first one in .177.  It's not a scale replica of anything, just kinda made it out of some 3/4" brass (pretty sure it's Alloy 360.)  Still needs polished, trunions installed and flash hole drilled (1/16").  Not sure what kind of base I'll do, but it will be something metal - I'm not much on woodworking!

I've never really messed with blackpowder, but I have built golf ball launchers, machine gun simulators, air cannons and the like.  I'm no stranger to firearms and reloading (smokeless).

Here are my questions -
What kind of powder and how much to start with?  I can't imagine even getting enough powder into this thing to blow it up!

For the brass coehorns, how are you attaching the trunions?  Are they pressed in or brazed or soldered?

I've seen reference to using a hot wire for ignition instead of a fuse.  How does that work?  Would it be feasible to run a piece of Nichrome wire into it and use a battery for ignition?

The next project is going to be either a bowling ball mortar, or preferably a bowling pin mortar - I can get pins easier than I can get balls!  Maybe  a soda can mortar as well.  We have a machine gun shoot coming up in June and some big boomers would be a nice addition.

Thanks in advance!

Vince

http://bloomautomatic.com/177mortar.jpg (link if the pic doesn't work)
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Offline Will Bison

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My first mortar - and first post, and a few
« Reply #1 on: March 16, 2006, 07:41:10 AM »
Way back in another century I had some .177 M/L guns. Seems like a .22 short case of 4 or 5f BP worked OK. Mine were all drilled for JET-X fuse but I don't know if it's still available.

Bill
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Offline GGaskill

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My first mortar - and first post, and a few
« Reply #2 on: March 16, 2006, 09:27:12 AM »
I have used nichrome ignitors and they work well although I see a problem preventing a short circuit in such a tiny touchhole.  Maybe you could pre-heat the wire to get an oxidized surface on it and that would be enough insulation to keep the mortar tube from shorting the loop.  Maybe just paint the wire and renew the paint as needed.
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Offline bloomautomatic

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My first mortar - and first post, and a few
« Reply #3 on: March 16, 2006, 11:05:59 AM »
I figured the nichrome would be tricky for something this small.  Was thinking of using insulated copper with a small bit of nichrome at the end - kind of like a model rocket ignitor.

I dunno, I'll probably just go KISS and stick with the fuse.

Got some ideas for the base.  Will post pics when its done.

Vince
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Offline Santa Dave

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Jetex fuse
« Reply #4 on: March 16, 2006, 12:05:06 PM »
Jetex fuse is RARE!
The only seller that I know of only will sell it as part of another sale!
I did manage to find some on ebay and got  2 yards from england (american made fuse)
Dave
Anybody else even looking!
for those of you who have not thought it out; as the bore gets smaller the touch-hole (vent) bcomes a larger percentage of the total.
when firing a .25 cannon with .125 vent AT LEAST 1/3 of the gases escape from the vent! very hard on performance!
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Offline Cat Whisperer

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My first mortar - and first post, and a few
« Reply #5 on: March 16, 2006, 12:06:21 PM »
Vince -

Welcome to the board!

We'd love to see some of your action shots of mortars and cannons (non-class III of course - outside the scope of this forum).

Bowling pins eh?
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Offline Santa Dave

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Jetex fuse
« Reply #6 on: March 16, 2006, 12:07:24 PM »
Jetex fuse is RARE! :shock:
The only seller that I know of only will sell it as part of another sale!
I did manage to find some on ebay and got  2 yards from england (american made fuse) :)
Dave
Anybody else even looking!
for those of you who have not thought it out; as the bore gets smaller the touch-hole (vent) bcomes a larger percentage of the total.
when firing a .25 cannon with .125 vent AT LEAST 1/3 of the gases escape from the vent! very hard on performance! :x
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Offline Cat Whisperer

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My first mortar - and first post, and a few
« Reply #7 on: March 16, 2006, 12:27:35 PM »
Jetex fuse - it's been early 1960 something since I've seen it!


I wonder, though, if it could be mimicked?
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Tim K                 www.GBOCANNONS.COM
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Offline bloomautomatic

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My first mortar - and first post, and a few
« Reply #8 on: March 16, 2006, 06:01:11 PM »
So what exactly is Jetex fuse?

Also, what about just countersinking a hole and have some powder lay in it like a flashpan in a muzzle loader?  As long as it was at low elevation, it shouldn't lose much.

I'm not real concerned about "performance" and how much is lost out the flash hole.  I'm mainly making it for the fun of making it.  Will probably shoot it a few times and put it on the desk!

What I really want to build is something sizeable that leaves a mark when it hits!

Vince
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Offline GGaskill

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My first mortar - and first post, and a few
« Reply #9 on: March 16, 2006, 06:37:39 PM »
A Jetex was a little rocket engine used on model airplanes back in the dark ages.  They used a fuse to ignite them instead of the electrical ignitors used by today's Estes rockets.
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“If you're not a liberal at 20, you have no heart; if you're not a conservative at 40, you have no brain.”--Winston Churchill
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