The Craftmans Shop > Backyard Ballistics

Black Powder Cannon

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bertie_bassett:
That looks a very long job making it from solid bar. And a lot of wastage.

cnc would probably do a good job of milling away the trunion ring complelty, and in sure with the right tools and a huge amount of time it could even be done manually. Would certainly be an accomplishment to make it from on big lump

Arbalist:
Agreed, but it must be the strongest way of making a cannon barrel, especially if it's a high grade steel.

BronxFigs:
I need your experienced opinions....

Let's say that I will turn a barrel from solid steel, and either silver-solder, or weld the trunnions onto the barrel.  The full diameter of the barrel where the trunnions will be welded is 3.00". 

My question is:

Should I do all the work on the trunnions, i.e. welding, etc.  BEFORE drilling and reaming the barrel bore?  I'm thinking that if I first drill and ream the bore and then apply a welding torch, etc... is it possible for the localized heat to warp the barrel, and thus, have a warped bore as a result?

Also...does it matter if I machine a barrel using either hot-rolled or cold-rolled steel?  Are there any real differences in this particular application?  Are there warping stresses involved with machining these steels?  Could I use either, one or the other?

Comments and suggestions are wanted.


Frank

Jonny:
I would drill and finish the bore before turning o/d.

Trunions the easy bit unless 5 axis in bulk but then have to set and proggy the thing for one part. Far easier and quicker manually, i do things like that daily that cnc ers refuse to do, well they just want easy work - too much hassle.
Far easier bore through to dia required, make a jig to suit bore and horizontal rotary table jobby, spigot either before, during or after.

Eugene:
Here is a link to a site that shows the making of a full size punt gun. The processes would easily scale down for your purposes.

http://forums.pigeonwatch.co.uk/forums/topic/217901-making-a-gunning-punt-and-punt-gun/

The simplest way to attach trunnions which avoids any chance of compromising the barrel metallurgy is to enter/ weld them into a collar and shrink fit the collar to the gun. I've seen a lot of punt guns done that way.



In the gun above the entire breech section complete with trunnions welded in is shrunk on very neatly and successfully.

Eug

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