K.I.S.S. bowling ball mortar

[The Jeff]

I've been trying to come up with an uncomplicated way to make an easily removable vent liner for a long time. I'm almost ashamed to admit it, but drilling out a socket cap screw never occurred to me!

[Double D]

I've been trying to come up with an uncomplicated way to make an easily removable vent liner for a long time. I'm almost ashamed to admit it, but drilling out a socket cap screw never occurred to me!

I would like to thank you for recognizing my brilliance, but like most things I do here, somebody else probably came up with it first.  I jusy modified or copied it.

[1Southpaw]

Sounds like a more logical explanation Zulu .  I have pulled a few lanyards on 105s when in Artillery school at Fort Sill .

[Doc Brown.]

EDITED TO OPE

[GGaskill]

Normally a mortar is two calibers (bore diameters) long which would be 7" in your case, plus the chamber length.  What are you going to use for shot?  Are you going to use light loads as well as full charges?

[Doc Brown.]

 EDITED T OAPE

[Double D]

The American Artillery Association has standards for a mortar---bbl length, etc.  Look at the  links in the Safe  loads and construction sticky at the top of the board.

There probably is some so simple mathematical way to do this, but..  Compute the maximum powder charge for the diameter of the powder chamber mortar you are building.    Bore hole in a piece of wood the dimater of the powder chamber until it is deep enough to hold the powder charge.

[Doc Brown.]

EDITED TO OPE

[Double D]

Thanks. I like this drill a hole in wood technique.  After looking around online for mortar stuff I come across a few things that make me feel like its almost impossible to blow up a mortar. A guy says he loads this with 800 grains and flour and paper. The breach wall is about as thick as tin foil.
 

There is a difference between a fireworks mortar and the mortars we build here..  If all you want OT do is make a loud nose and irritate the neighbors then this is what you want....to learn more about them and how they are made the Google fireworks and pyrotechnics and see if you can find a dedicated forum for those type things. 

That's not really what this board is about...and definitely not this thread.

[Double D]

Here's where we are on this project.



Left to do on the barrel is attach the trunnion and install the vent.

Lots of work to do on the base.

[Zulu]

Wish I was there to help you.  That looks like it is going to be awesome!
Zulu

[Double D]

I can tell you, I can use the help!

[BoomLover]

Looks like a slightly bigger version of the Coffee Can Mortar! (like twice the size!...and a lot heftier!) Looks great, Douglas!

[Ex 49'er]

Don't break your back moving it!

[Double D]

South Paw and I did the trunnion holes this afternoon.  We used the milling machine  as a heavy duty drill press.

First the set-up.



Then I drilled the holes.  Started with the center drill, followed by 1/2" drill through for a pilot hole.   Then I drilled a 1 1/8" hole for the 1"-14 cap screw.  I then drilled the 1-1/2" seats for the cap screw head.  Because we didn't want to drill into the table top, the 1 1/8"holes were drilled about  1/2" short.



To get the 1 1/8" hole all the way through.  We rotated the trunnion 180 degrees on the table.  Then using the 1/2" drill we lined up the holes and drilled with the 1 1/8" drill--worked perfect.



Time to bolt everything up and see if we got it right. First straght to the plug.



Then with  the  breech plug in place.



We did it right.

One thing Southpaw and I noticed bolting the thing together---its heavy.  So how heavy is it?



Next the vent liner hole and vent installation.

[Victor3]

"Because we didn't want to drill into the table top, the 1 1/8"holes were drilled about  1/2" short."
 
 That's always a good idea, especially when you're using someone else's machine. 

[little seacoast]

Youzah! That is gonna be one huge heavy sucker when you're done DD. The base is going to weigh at least 300 lb too, hope you've got a crane and power lift on that truck of yours. It's amazing how fast the weight increases with scale, I've found my half scale Parrott and the new 3/4 scale one I'm working on to be a world apart in ease of use and movement. I'd love a mortar like yours but I'm not man enough to move it. A few years ago I developed a passion for a drift boat- until I realized it didn't come with a husky 20 year old to row it.

[Double D]

I  noticed the bowling alley was open when I went down town today.   Stopped in and asked about bowling balls. They gave me six.  Five were all orange 6 pound balls.



Here is the best part.....



They float.  Southpaw and I are going to set these aside for shooting in the pond. 


Click on picture to see video.


 

[The Jeff]

Looks great DD! It's really coming together!

[GGaskill]

So did everything pull up tight like it was supposed to?

[jamesfrom180]

Catching up and came across this.  Double D never disappoints.

A quick thought at the weights that seem to be accumulating.  Have you thought about putting a lifting point on this monster?  I was thinking that a recovery point used in 4 wheel drives might be a good start.  See link below for a product that came to mind. 


http://www.bigcountrycustoms.com/store/product/recovery-points/

[Double D]

So did everything pull up tight like it was supposed to?

Yep sure did George....

We'll do the Vent next and then some more test fires.

[GGaskill]

Did you put any gasket sealer around the plug/tube joint on the inside to minimize fouling incursion?

[Double D]

Did you put any gasket sealer around the plug/tube joint on the inside to minimize fouling incursion?

No not yet.  That will be done in final assembly.  The barrel is going to be profiled this winter and the barrel has to be disassembled to do that.

[Double D]

I will  note that in the other K.I.S.S. mortars when disassembled, there was no sign of powder fouling intruding into the space between the wall of the barrel and the breech plug.  What was noticed was the intrusion of water from the cleaning processes into that joint.

For that reason this issue of sealant is an important one in this gun because of it size.  While the popcan and golf ball K.I.S.S. mortars are fairly simple to disassemble and clean, this monster is not.

[Double D]

Catching up and came across this.  Double D never disappoints.

A quick thought at the weights that seem to be accumulating.  Have you thought about putting a lifting point on this monster?  I was thinking that a recovery point used in 4 wheel drives might be a good start.  See link below for a product that came to mind. 


http://www.bigcountrycustoms.com/store/product/recovery-points/

Yes I have though about this and  have not eliminated it.  If use it, and it is likely, it will add after the barrel is profiled


NOTE: the mortar in the video above shooting a ball into the pond is not my mortar but Southpaws before he painted it.

[GGaskill]

I am sure we discussed this once before and came to the conclusion that anything under 12 pounds would float.  That one appears to be only half way under water.

Having rechecked the calculations, 12 pounds is the point.  Depending on water temperature, a 12 pound bowling ball will just float or just sink.

[Cat Whisperer]

GOOD to see it coming together.  400+ lbs is too much for me.  My 4.55" weighs in at 103 (tube and trunnion).  I'll use it until I can no longer move it.

[Double D]

GOOD to see it coming together.  400+ lbs is too much for me.  My 4.55" weighs in at 103 (tube and trunnion).  I'll use it until I can no longer move it.

Yes indeed building a gun this big id pretty daunting.  The design must include how to move it.

This is the concept I will be building to.

[Zulu]

Cool!
Do you have wheels yet?  How tall will they be?
Zulu