Author Topic: FIRST ATTEMPT AT MORTAR PLANS (Read 706 times)

pmmarionneaux · « **on:** January 15, 2005, 08:46:03 AM »

POSTED DRAWING ON GBO PHOTO SITE...MAYBE THIS LINK WILL WORK http://www.graybeardoutdoors.com/phpbb2/album_pic.php?pic_id=611

SEEK COMMENTS

Cat Whisperer · « **Reply #1 on:** January 15, 2005, 09:07:56 AM »

Good show Dude!

It will be pleanty heavy and strong.

Suggest doing a radius on the inside of the tube in two places (insted of the sharp inside corners). A sharp inside corner (at the bottom of the bore) is a stress point - with a radius it's MUCH stronger.

You will find that doing a radius on the inside and outside corners at every change of diameter will have a very good affect on looks as well.

Cat Whisperer · « **Reply #2 on:** January 15, 2005, 09:11:26 AM »

Also - you might want to move the two bolts out closer to the edges of the tube.

Double D · « **Reply #3 on:** January 15, 2005, 05:46:22 PM »

I would skip the drilling and tapping and mating up process, and weld the trunion on. Seems to me to be a much stronger connection at point of high stress.

I agree with CWabout the radii in the corners inside for strength and outside for cosmetics.

You are going to end up with a neat looking gun.

Cat Whisperer · « **Reply #4 on:** January 16, 2005, 02:53:14 AM »

This is a point where DD & I choose different methods. My choice is to avoid the issues of cracking (with 4140 and welding) and use socket head cap screws (SHCS) to bolt the trunion to the tube. I figure it's in the area with the most mass and has the greatest ability withstand the forces within and that two tapped holes at the edges wouldn't affect necessary strength.

Either method will work if done right.

A minor advantage of being able to disassemble the tube and trunion is that on iron base the trunion rings can be permanent, being able to unscrew the SHCS's to disassemble the tube from trunion and slide the trunion out.

FWIW