trunions

[Cat Whisperer]

Attaching a one piece trunion to the base of a mortar is relatively easy - just cut the groove and sink two socket head cap screws - that's why I've used it often.  But on the 1841/1861 seacoast mortars the trunions were cast into the barrel near the muzzle.

So far I've cut the bore and OD of the tube.  Now to inlet the holes for the trunions to set into prior to welding:




Some folks have threaded the trunions or put a bolt inside, but I think just inletting a 1/2" deep for a 1-1/2 or 2" diameter trunion should be enough - especially in golf-ball caliber.

[Cat Whisperer]

The dial indicator was out of curiosity.  Since I cut the OD and the bore from holding the tube in about the same place with a 4 jaw chuck I wanted to see how true this setup was to the other - .003" TIR!  

Have to cut the trunions next, then mill and weld them in place.

[CU_Cannon]

Here are some plans I found a while ago.  They might give you some ideas.  

I don’t know origin of the drawing; I can't remember just where I found them.  I don’t think they are copy writtenbut if there are any problems I can remove them.

[Cat Whisperer]

CU -
Thanks for the pix of the 1861/13" Seacoast Mortar.  I think I've got a set right much like it.  Mine will be similar, but closer to the 1841/10" Seacoast because I like the sideplates' simplicity a little better.

Cut the pockets for the trunions:



If I ever do it again I'll have a much more sturdy fixturing than what you see here.  Got away with it.

Trunions and welding next.  Maybe this weekend.

[Cat Whisperer]

Well, spend most of the day at work.  Asked the boss if I could have some of the scraps from the machine shop - he said to help myself.  So, a couple of pieces of 1116 are shown here in slightly modified form -




Smooooooth cutting steel!  Won't need any polishing.  I'll weld them in after the next operation - cutting the spherical radius on the end.

Now I HAVE TO make the radius cutter!