POWER CHAMBER

[ROGER W]

BUILDING A GOLF BALL CANNON using 30" 1.75" ID DOM PIPE & 18"DOM PIPE OVER THE 30" PIECE ,don't KNOW ABOUT THE POWER CHAMBER, WILL BE using A FUSE TO IGNITE, DO I MACHINE A HOLE IN THE END PLUG,    PLEASE HELP

[Double D]

Roger,Welcome you are among friends here.  You will get the help you need.

First turn off you cap lock key, it makes your post hard to read, besides all caps is the same as shouting on the  internet. Some of us here need yelled at, being deaf O.F.'s, but most of us e can read just fine.

Is your base plug solid or have you built a powder chamber in the plug?
If you have a chamber drill your vent or fuse hole in the side of the tube so it comes out just before the bottom of the chamber. If you don't have a chamber, drill the hole just before the end of the bore.

If you are drilling through an outer tube and inner tube into the chamber in a plug or just through two tubes in to the end of the bore you will need to make a vent or fuse liner to keep black powder fouling out from  in between to the two pieces.  If you don't the fouling will corrode out and make your gun weak and your gun could burst.

What ID is the 1.75 id DOM tube?  What is the purpose of the 18 inch DOM? You can use any kind of Seamed pipe over the DOM for visual effect.

Use that 18  inch DOM to  make a second cannon.

[Cat Whisperer]

Roger -
 I'm going to assume the shorter DOM is to sleave over the smaller.  Good technique for adding strength.

Measure a few golf balls.  I've done mortars in either 1.70 or 1.75 id.  I have a Napoleon cast iron tube in 1-7/8 (which is a bit large but it works).

Design of the breach is important.  DD has some realy good techniques on this.  Typical method is to thread and weld.  If you're welding my concern is cracking of the metal.  What material is the DOM?  4130 is commonly available and is weldable IF done right (4130 is just at the end of the range considered weldable).  Preheating is a must, as is slow cooling.

You will get really good velocity with this length - I have yet to find ANY golf balls I've fired with the Napoleon.  Most move out too fast to see and all are gone out of sight or deep into the backstop.  (I much prefer to watch the golfball coasting along in a high arch from the mortar.)

[ROGER W]

thanks for the help sorry about the all caps , the base plug is solid i will drill the vent hole jest before the plug , the 18" dom pipe was for added strength , good ideal for the 2nd cannon,    i don't know the dom pipe # [4130] it is dom 3/8" wall seamless 1.75" id pipe , can i thread & thru bolt the base plug and not weld it would be nice for cleaning ?  thanks again for your help       from the mountains of virginia also ,roger

[Double D]

A threaded and pinned breach blug is a good idea.  You will need make up some sort of spanner wrench for removing the plug.  You also want the face of this type plug to be larger that the bore diameter so the face of the plug seats against solid flat in the tube.  Much like a gun barrel seats in  Mauser rifle.