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Offline oyvind

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New mortar, I have a plan.
« on: July 06, 2009, 02:14:56 AM »
Hi.
I have a plan.
what you think about this?

Mvh









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Offline KABAR2

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Re: New mortar, I have a plan.
« Reply #1 on: July 06, 2009, 02:44:32 AM »
Looks very much like some of the Confederate coehorn mortars just need to round the base,

your trunnions should be a bit bigger in diameter,  but concept looks sound,
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Offline Cat Whisperer

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Re: New mortar, I have a plan.
« Reply #2 on: July 06, 2009, 02:46:42 AM »
Observe the avitar on the left.

4.55" bore

4140 steel

Uses 4" pvc pipe (4.50" diameter) filled with concrete.

Only differences are that the breech end is rounded a little and that the trunion is cylindrical the entire length.

Industrial hard-chrome plated.

Tube and trunion weigh 103 lbs.
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Tim K                 www.GBOCANNONS.COM
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Offline BoomLover

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Re: New mortar, I have a plan.
« Reply #3 on: July 06, 2009, 03:34:12 AM »
Very precise drawings, easy to see the concept, but I agree that the trunnion needs to be larger in diameter. That is almost identical to the CSA Mortar I built, and should work fine. KABAR2 and CW are both long time members and builders, and they offer great advice, oyvind! BoomLover
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Offline Cat Whisperer

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Re: New mortar, I have a plan.
« Reply #4 on: July 06, 2009, 05:34:17 AM »
The trunions on mine are 2" diameter and extend 2" from the tube.  Trunion is from 1018 steel.  Supported 100% in the base - no fear of bending it.

If you make it from round stock you could mill a flat on one side; or as I did I milled a round groove in the base of the tube.

I used socket head cap screws to secure it much as in your drawing.  You don't NEED 4140, I did it just becasue it was my 2nd mortar and I tend to overbuild things.

Barrel length is good.  It will be a 100-200-300 yard range mortar.  IF you wanted longer range, you could lengthen the tube a bit.
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Offline oyvind

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Re: New mortar, I have a plan.
« Reply #5 on: July 06, 2009, 07:46:44 AM »
Thanks for good advice.  :)
How much weight have your Projectile?
Was going to create a lifting point on projectile
to make it easier to charg and simultaneously have a rope to easily find projectile.
is it good ?


mvh

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Offline Double D

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Re: New mortar, I have a plan.
« Reply #6 on: July 06, 2009, 08:09:58 AM »
Quote from: Cat Whisperer on July 06, 2009, 05:34:17 AM

Barrel length is good.  It will be a 100-200-300 yard range mortar.  IF you wanted longer range, you could lengthen the tube a bit.

I don't realy believe lengthing the barrel will help. If you increase the capacity of the powder chamber range will increase.  The Coehorn's range and siege mortars range were increased by adjusting powder charges.
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Offline Cat Whisperer

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Re: New mortar, I have a plan.
« Reply #7 on: July 06, 2009, 08:27:58 AM »
The longer the barrel, the more use of the charge employed.

With a longer barrel it's then more of a howitzer.

The muzzle blast is much more intense with the shorter barrel too!

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Tim K                 www.GBOCANNONS.COM
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Offline Cat Whisperer

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Re: New mortar, I have a plan.
« Reply #8 on: July 06, 2009, 08:34:59 AM »
The 4.5" cylinders of concrete weigh about 7-1/2 lbs.  Takes 2 or 3 35mm film cans of powder to fill the powder chamber.  Might want one a bit bigger.  I've gotten 450 yards maximum from a 7.5 pounder.  100 - 200 yards is MUCH more comfortable - as you can SEE what you're going to hit.

The zinc spheres are 10 lbs each.
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Tim K                 www.GBOCANNONS.COM
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Offline NitroSteel

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Re: New mortar, I have a plan.
« Reply #9 on: July 15, 2009, 09:20:03 AM »
I've got similar pieces of material at the shop and was thinking of making a similar mortar, this post is actually alot of help.  Mine is 6" in diameter OD and 4" diameter ID.  I was thinking of using a 12inch piece of tube and plugging the reach 4 inches with a piece of 4" round stock (powder chamber bored into it).  Was also planning on using a piece of 1.5 inch round stock for a trunnion and placing in a traditional style carriage built of oak. 

Wasn't sure how big to make the powder chamber.  Distance is great, but I really want alot of volume more than anything.  How long should I make the tube?  What diameter/depth should I make the powder chamber?   

Thank ya'll

NitroSteel
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Offline GGaskill

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Re: New mortar, I have a plan.
« Reply #10 on: July 15, 2009, 10:12:35 AM »
Distance is great, but I really want a lot of volume more than anything.

Volume meaning loudness?  If you simply want to make noise, a thunder mug is probably your best bet.  And it saves you the trouble of making a carriage/mount.
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Offline NitroSteel

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Re: New mortar, I have a plan.
« Reply #11 on: July 15, 2009, 11:27:40 AM »
I saw a "thundermug" on a pyrotechnic website last week.  What is the design criteria for one of these?  How big is the powder chamber and what does it fire?  From what I read, it promised to be very loud, but there was no real description.

I think I rather make it "look" like a mortar (for look's sake), but I'd be just about as happy with it being really loud and firing nothing.  Does being short make it (mortar) louder?  What should I shoot?

Thank you,

NitroSteel
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Offline GGaskill

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Re: New mortar, I have a plan.
« Reply #12 on: July 15, 2009, 11:53:56 AM »
The feature of a mortar that makes it less loud than a cannon of the same size is the small chamber followed by the large bore.  If you make the bore the same size as the chamber, it will be much louder since the expansion will take place in the air instead of in the large part of the bore.  If you make a half scale Coehorn but bore it 1" for the whole length, it will be much louder than the same thing done for beer cans.
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Offline oyvind

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Re: New mortar, I have a plan.
« Reply #13 on: July 15, 2009, 11:58:03 AM »
 ;)
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Offline oyvind

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Re: New mortar, I have a plan.
« Reply #14 on: July 15, 2009, 12:05:19 PM »
Quote from: NitroSteel on July 15, 2009, 11:27:40 AM
I saw a "thundermug" on a pyrotechnic website last week.  What is the design criteria for one of these?  How big is the powder chamber and what does it fire?  From what I read, it promised to be very loud, but there was no real description.

I think I rather make it "look" like a mortar (for look's sake), but I'd be just about as happy with it being really loud and firing nothing.  Does being short make it (mortar) louder?  What should I shoot?

Thank you,

NitroSteel

Design criteria: wall thickness equal caliber.
Good steel quality.
I have one that has 33mm caliber and about 20cm high.
Takes 1 35mm film cans of ffg powder.Good response.
Little rockwool insulation wadding is good   
mvh
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