NG Wondering What To Build

[Mickey_D]

NG here with a strong itch to build a 6 to 12 pound size cannon and I am looking for tips on what to build.  I own a cnc machine shop and have done a fair amount of fab work in the past, so I would like to build the gun and carriage in house (probably going to buy wheels because they look like a PITA to make for the first time).  I have a cnc lathe that will swing 9.25" over the carriage, so a 12 pound Napoleon is out, but I was thinking about possibly a six pounder or a 12 pound howitzer.  Available material is 8"OD 4.5"ID (1.75" wall) certified 1026 steel (fairly easy to weld the trunions on and finish weld the shrunk in breech plug) or 8" 4140 with a 4.25" bore that sucks to weld on and would have to go out for x-ray testing before I would fire it.  If I do a 6 pounder I will have to source some new material.  Both will have to be finish bored to 4.62".  I also need to stay under 72" length because longer will just get to be too hard to handle.  Any tips on which way to go would be greatly appreciated.

[GGaskill]

If this is your first cannon in excess of 1" bore, I would go with something beer can bore (2.65") or smaller.  The full size stuff gets extremely heavy and impractical for one man operation.  And transportation is also a problem.

Maybe a Napoleon in golf ball bore (1.72") would be a good first gun.  Not too big but a substantial gun.  Good for reduction of Ft. Pallet with Fox balls.

[Victor3]

 Someone on here once said, "It's better to have a friend who owns a full size gun than to own one yourself."


 About every increase of 1" in bore size requires what appears to be an exponential increase in everything (manufacture, moving, storing, feeding, etc) associated with a cannon.


 But heck, if you're up to it, go for it. 

[Mickey_D]

Anyone have online dimensioned drawings of an 1841 field howitzer?  The lines on it look nice and I think it will fit in my machines.

[Double D]

Buy the plans for the Guns you want from Antique Ordnance Publishers  http://gunneyg.info/html/AOPCatalog.htm .

[Cannoneer]

Welcome aboard! It sounds like you've got the machinery to make a full scale model, and the means to maintain it; so why not? Please post progress photos of the build if you decide to go ahead with the project.

[Mickey_D]

I figured out how to space up the head and tail stocks on the lathe so swinging 12" over the cross slide will not be a problem, and I can even space up the tool turret to keep the tool tip angles right.  I am going to order a couple of different plans to get a better idea on dimensions.  One thing that I have not seen much about on the web is the shrink fit allowance for the chamber plug.  Looks like the old reliable copy of the Machinery Handbook and some figuring with the Engineers Toolbox will come in handy here unless someone has some other good pointers. 

[Victor3]

 Shrink fit formula...


http://www.engineeringtoolbox.com/assembly-shrink-fits-d_951.html




Edit - Oops, you already found that I see. Link might be a help to others so I'll leave it. 

[GGaskill]

The usual shrink fit allowance is .001" per inch plus .001" and there is no reason we have found to be different.  However, it is expected that the back of the plug will be also welded to the tube with a substantial weld.