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Discussion Starter · #1 ·
My first introduction in the hobby that goes boom was an interest in bowling ball mortars. Started with a "K" cylinder and installed trunnions. The "K" provides a nice loose fit for the ball even with fouling. We had a lot of fun until we increased the powder charge until a trunnion failed...that was a sad day.

My thought process on the next iteration was to avoid trying to manage/contain the energy. I really like the design of the seacoast but I did not have your' insight. We did a short diversion with the next smaller cylinder but was uncomfortable pounding the ball to seat.
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Automotive tire Wood Cylinder Gas Asphalt
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Sky Land vehicle Train Vehicle Plant
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Discussion Starter · #2 ·
I got a little meshed-up on that first post I think?

Anyway, on to a new iteration. Next I used the base of the cylinder as a base for the motar. Then we used a 3/8" pipe to cover the chamber for added insurance. This seems to work pretty well for a more "vertical" type of trajectory. Big fun indeed & no welding on cyclinder.

Does 1/2 cup #2 sound about correct????? for a 17 sec hangtime and about 400 yards?

The goal was simple: safe, simple, don't worry about the energy and kind of short range so you don't have to hunt balls all day.

It started off trying to be streamline and not too heavy but with the tilt trailer it's not too bad to handle :-O
 

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Haven't seen a mortar set up quite like that before . It looks like you are loading the powder through the oblong hole then sliding the outer sleeve down to cover it . Would be nice to see more detailed photos. One thing I would caution on near vertical shots is that wind can catch the ball and send it back behind the firing line. We had it happen once, nothing quite like hearing a bowling ball whistling coming down overhead . Everyone froze and waited for it to hit. It fortunately missed everything of value and hit about 100 yards behind the line. After that we only shoot at close to 45 deg.
 

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Discussion Starter · #4 ·
I thought I had better pic's but not. I cut a rectangle hole in the bottom of the cylinder through the real thick meat. Welded a flat plate for the bottom and then cut a fuse hole to install and light the fuse (muzzle loader). Then I welded some square strap to the base and then to the inside of the sleeve just to keep it together. The cylinder can actually slide out with some encouragement.

You are way spot on about the wind (we live in WYO). I put as much lean/tilt as I could but still stand-up. Buying "failed" is a little sketchy but if you can find them clean (no corrosion on the inside) that had an arc spot way up high (anything with any kind of arc is scraped) the odds are pretty good (like a coconut.. you don't really know what you have until you open it up).

With a vertical ish firing angle I feel pretty good about good ignition. I am working on IV that will be more of a distance shooter. Using a cyclinder without a blast chamber I am concerned about the charge laying on its side. Thoughts?
 

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If I am understanding you right the main reason for a powder chamber is to control pressure , a high- low pressure situation. Protects the cylinder barrel from the full pressure of the powder upon ignition. You didn't say just what the oblong hole in the side of your barrel was?
 

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Using a cylinder without a blast chamber I am concerned about the charge laying on its side. Thoughts?

Load it with the tube vertical, then tilt to firing position. The shot will keep the powder centered under it.
 

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I am not understanding what I am seeing and what I think I am seeing, looks scary.

How about some more details about what you are doing?

Do I see an oblong hole cut in the side of the cylinder so you can load the powder. Then the sleeve then slides down and covers the chamber. is the ball then rolled down from muzzle to the powder and the trailer tilted so the gun can be fired? Is that is what I am seeing?
 

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Discussion Starter · #8 ·
Sorry guys let me back-up.

K cylinder cut for desired OAL.

Then bottom cut at an angle for desired lean/barrel tilt like the "mock-up" below
White Light Black Automotive tire Road surface
White Light Black Automotive tire Road surface

Then cut a rectangle in the base for the valve/nipple to be exposed
Wood Musical instrument Artifact Gas Tints and shades

Then cut a slot in the base to gain access to the nip.
Automotive tire Automotive design Automotive wheel system Rim Auto part

The Nip is made the full length so it flush with the ID. SST Nip just cause I got a free chunk.

Then the whole blast/base is surrounded by a 10" x 3/8" thick sleeve (neighbors are great).

Pretty solid & Safe??,
 

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Discussion Starter · #9 ·
My goal was not to put too much "john/me/over-kill" on-it so it was weight manageable, well maybe next time.....

So the carriage design was focused on "no touchy/lifty" so the skid as added with a long trailer tongue so I could just tip it up and drop it off. I need a
 

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Sorry but you have presented a construction method that I am not familiar with , if you can would you please show your build process step by step without skipping any and the steps to fire it. I feel kind of dumb not being able to make any sense of your mortar . Thank you for your patience.
 

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Discussion Starter · #12 ·
Sorry Moose, I mixed topics. This specific version I call #3 (or Who Dat, a little Louisiana lingo).

#3 is a typical cylinder "type K" build but instead of having trunnions I wanted the ground deal with the energy to avoid mechanical trunnion related failure and omit welding or shrink fitting sleeves. Instead, the neck end of the cylinder (where the valve would go but now a nipple for a fuse hole) is inverted and rests in the rectangle hole of the fabricated base (which was the bottle of the cylinder that I cut).

The mortar is charged by:
1. insert fuse through nipple enough to be seen inside
2. Tip mortar vertical and add powder to suit (1/3 to 1/2 cup...but how much is max ANYONE KNOW?)
3. The powder lays nicely in the center and the ball is seated firmly (seating is really beneficial).
4. Light fuse...enjoy

The intent of this post was to introduce a version or a mortar I had not seen before.

I think it best if I start a new post for #4

Does this help?
 

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I think I have this figured out. What think I see is scary,

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I thing what you are doing is filling the empty space of the threaded neck with powder and firing, is that correct. This is not safe.

Basic standards call for a powder chamber to have wall one caliber thick. That is, if the diameter of the powder chamber is 1 inch, then the walls of the chamber should also be one inch. 2 inch chamber, 2 inch walls.

If you are interested in building good safe bowling ball mortar for these cylinders we can help you. Stick with the traditional, they have built safety features. What you have built so far is scary,

Also if you stick with traditional and replicate original you will be on better grounds as replicas of antiques are exempt for the most part from the Firearms regulations.
 

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Discussion Starter · #15 ·
Well I hope I pre-apologized for not being the best written communicator, sorry for all the confusion by mixing topics.

I guess I have blown the newbie of the year award.

The purpose of the cut-way was only to share what the inside of an "S" cylinder looks like compared to a bowling ball (friend has a saw big enough and he had a scrap cylinder and boys will be boys, so I cut it to see). While I have done a little research on compressed gas cylinders I was posting to see if there was any interest in a new topic.

One of the reasons I joined was to learn about those types of rules of thumb (I lean toward bigger is better). So sincerely I would be very interested in general safety standards.

#3 fuse nipple 303 SST threaded 3/4" NPT (the original cylinder thread) and elongated to pick up more thread and match the radius inside.

Does that help?
 

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Discussion Starter · #17 ·
I'd like to finish this topic with just a couple of questions if you will,

Assuming a better understanding of the design & functionality of #3-cylinder design.

1. Seem like a safe design with whole blast/base area is surrounded by a 10" x 3/8" thick sleeve? Or do you think this is scary?
2. Has anyone heard of a max/min load for cylinder mortars (assuming a safe design)?
3. What types of cylinder mortar designs in this forum would you recommend?
4. Do you recommend a patch/t-shirt/wads for BB mortars?
5. Who are some good vendors for builders (preferably in the RM states or central/west?

Thanks,
JohnD
 

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1. Seem like a safe design with whole blast/base area is surrounded by a 10" x 3/8" thick sleeve? Or do you think this is scary?
Powder chamber is not properly constructed correctly. If it ruptures the sleeve has no way to contain the gases. at best it will just divert the gas.
2. Has anyone heard of a max/min load for cylinder mortars (assuming a safe design)?
Look at the stickies Safe loads and Construction. The diameter of the powder chamber determines the maximum safe load. The sticky has that information.
3. What types of cylinder mortar designs in this forum would you recommend?
This is really a long discussion subject. But I'll try a short version. I use to have some drawings but lost them with the loss of my photo host last year, I'll look for them on my back up drive and post them if I find them. I would make a powder chamber to safety specs, I would weld that chamber in the bottom of the cylinder and then weld a trunnion on the bottom of the cylinder. Then build a carriage.
4. Do you recommend a patch/t-shirt/wads for BB mortars?
Patches are not used in cannons or mortars. Wads are some time used in cannons to go between ball and powder and in front of ball to hold it in the barrel. Ball ar always losed loose in cannons and mortars.

5. Who are some good vendors for builders (preferably in the RM states or central/west?

Thanks,
JohnD
I am aware of a couple of builders of bowling ball mortars but only one I would recommend and that is Dom Carpenter of morecannonfab.

From what I have see of you building so far, I think you could build you own. You just need some guidance,

Here is the one I built from seamless tubing .There is not a weld anywhere on this gun and it is built to meet safety guidlines. Fun range for this gun is 100-400 yards, but has fired a ball 1.04 miles. This gun weigh just over 800 lbs.

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If you realy want to build a safe gun we will help you. We will help you build a safe gun and one that looks good also.
 

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Double D Quote

"This is really a long discussion subject. But I'll try a short version. I use to have some drawings but lost them with the loss of my photo host last year, I'll look for them on my back up drive and post them if I find them. I would make a powder chamber to safety specs, I would weld that chamber in the bottom of the cylinder and then weld a trunnion on the bottom of the cylinder. Then build a carriage. "

Douglas, are either of these drawings what you are looking for?
Zulu

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Rectangle Parallel Font Plan Pattern
 

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No Michael the those are drawings for building a proper liner for lining cannon barrels. Thanks for those.

I collected over the years drawing from others and then drew a couple my self that showed how to make and install a chamber in one of these pressure bottles.

I just did a search of my back up drive. I found a couple of drawings for making a bowling ball mortars from tubing. I found one crude hand drawn that I made showing how attach the chamber..

Then I found this, One of our former member wrote this up for a project he was doing, I do not remember and I am unable to properly credit that person for there work. This is not mine,


If I find the original post I will add the link and give proper credit to the Author.

Guide for Building a Bowling Ball Mortar

Section 1: Materials

In order to construct your Bowling Ball Mortar, you will first need to acquire the proper materials to do so. The list that is provided below aims to direct you to the most appropriate materials at the least cost while not sacrificing anything by way of strength or safety.

Mortar Materials:

• K Sized Gas Cylinder. These are also identified by their Department of Transportation designation of 3AA2400. This type of cylinder is the ONLY type that will work and is what you must use for the barrel of your Bowling Ball Mortar. These gas cylinders are the type used by welding shops everywhere to hold pressurized gasses. Empty ones can be found at welding shops and at junk yards for reasonable prices. Before purchasing, make sure that the tank is EMPTY.

• A 6” diameter piece of solid round stock at least 6” long made of either 1018 or 1024 mild steel. This will be used to form the breech plug and powder chamber of your Bowling Ball Mortar.

• At least 12” of 3” diameter steel bar stock. This will be used to create the trunnions of the Bowling Ball Mortar. (Note: trunnion should be no less than the diameter of the powder chamber.)



9/16”-12 x 4” socket head screw for Vent liner



Carriage Materials:

• 4x 2”x12”x36” Lumber, preferably oak

• 4x 4”x4”x8” Lumber, preferably oak

• 10x .5”x14” Carriage Bolts

• 1x .5x 8” Fully Threaded Carriage Bolt

• 11x .5” Nuts that fit on above Carriage Bolts

• Wood Glue

Mortar Sponges:

• 2x .5” x 36” Wooden Dowels.

• 8x Old Socks

• 2x Zip Ties



Section 2: Construction

Following this section are engineering drawings to provide a reference to how to construct and assemble your Bowling Ball Mortar.

Step 0: Open and remove all valves on gas cylinder and leave it outside for AT LEAST 24 hours to ensure that the cylinder is EMPTY.

Step 1: Clean any rust or paint off of the Gas Cylinder.

Step 2: Cut off the top of the gas cylinder to remove the gas stem. The result of this cut should be that there is an approximately 6” diameter flat plane on the top of the gas cylinder.

Step 3: Using the new top of the cylinder as your measuring point, cut the Gas Cylinder down to a length of 18.” This length of cylinder will be your barrel. Ensure that your barrel length does not exceed 18" as this will adversely effect the function and stability of your Bowling Ball Mortar.

Step 4: Bore a 3” diameter hole into one end of the breech plug to make the powder chamber. This hole should be bored to a depth of 3” This is the chamber that will hold the powder and direct it's expanding gasses to propel the bowling ball. WARNING: DO NOT MAKE THE POWDER CHAMBER LARGER IN DIAMETER THAN ONE THIRD THE DIAMETER OF THE BREECH PLUG. LENGTH OF THE BREECH PLUG SHOULD BE AT LEAST TWO TIMES THE DIAMETER OF THE THE POWDER CHAMBER.



Step 4A: Drill and tap hole 9/16-12 for the vent liner in the side of the breech plug so the center of the hole is 9/32” up from the bottom of the chamber.

Step 5: Weld the breech plug centered on the 3 inch diameter trunnion with the vent liner hole 90 degrees to the trunnion bar.

Step 6: Insert the powder chamber with trunnion into the 6” hole in the top of the tank. Weld the tank to the trunnion bar and chamber.


Step 7: Drill a 3/16” hole through the center of the 9/16-12 x4 inch socket head screw


Step 8: Drill a 5/8” hole in the side of the tank 90 degrees to the trunnion to access the vent liner hole in the breech plug. . Insert the Vent liner through hole and screw into breech plus. Cut vent liner down so tip of liner reach chamber but does not protrude in to chamber. See Breech Plug drawing for positioning details.

Step 9: Cut out 2”x12” lumber following the contour shown in the Carriage Pre Assembly Drawing.

Step 10: Glue 2”x12” cut outs together in pairs.

Step 11: Assemble Carriage according to the Carriage Assembly Drawing.

Step 12: Put 4x socks on one end of each dowel, Zip Tie in place.

Step 13: Paint your mortar and carriage as desired. This is an optional step, however, painting your mortar and carriage will help to preserve them and protect them from the elements.


Rectangle Font Parallel Pattern Paper


Head Handwriting Slope Font Parallel


Rectangle Font Parallel Circle Symmetry


Rectangle Schematic Font Parallel Pattern


Rectangle Parallel Font Map Slope


Rectangle Font Parallel Slope Pattern

Rectangle Schematic Font Parallel Pattern



Let's review some basic principles of powder chamber design - which we've mentioned from time to time here.

The thickness of the metal around the powder chamber should be equal or greater than the diameter of the chamber (in all directions).

A quality steel should be used - mild steels are good.

With some alloys (4130/4140 and others) welding requires preheating and slow cooling to prevent cracking AND should be done by professional CERTIFIED welders.

Welding in areas where combustion products are present is NOT acceptable - porosity and corosion over time will cause failures. This is the reason SEAMLESS tubing for liners is a requirement.

Rounding the inside corners - or a spherical bottom of the chamber - is very good as it eliminates 'stress risers' - locations where stress is concentrated.

Tapering the powder chamber also is a good way of making it stronger.

The walls of the mortar can be much thinner because the maximum pressures of the powder burning are concentrated in the powder chamber and then are reduced greatly. Coehorn took advantage of this in the 1700's.

There are general rules for construction outlined by AAA and N-SSA that have been successfully employed for years.

Special attention around the fuse hole should be taken to preclude corrosion when using a liner.

Prudent loading is good.

There are good and bad designs. Probably everything out there can be improved in some way.

To sum it up four things must happen to keep safe: good design, good fabrication, good materials and good/prudent loading practices.

Again this document is not mine.
 
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