Posted by NEWTEC on December 02, 1998 at 16:12:42:
Hearing you talk about pressing a barrel into the trunnion and fixing a locking steel pin afterwards. I assume that barrels outer diameter and trunnion hole diameter are machined to allow a friction or roughness based adhesion. For those of you who do this sort of work on a constant basis there might be another way to make this fitting without expensive tooling or material.
This principle is applied in the industry as well. It is based on the expansion/shrinking phenomena encountered when one exposes material to high or low temperatures. I would try it this way: First cool down the complete barrel (especially the trunnion end) by placing it into a plastic bag and cooling this bag from the outside with ice cubes & salt in waterin a tub for a while until it is completely cold & this way reduce the outer diameter (optionally one could put it into the freezerfor a longer time)
Step 2: heat or warm the barrel trunnion with a bowtorch (of course under the temperature that has undesired effects on hardening qualities /NOT red hot) to enlarge the barrel hole by expansion of the steel. Then one can simply slip the hot barrel trunnion onto the cold barrel and wait until the expansion/ shrinking process that made the "fit" loosely reverses and closes the trunnion hole/expands the barrel dia. to make it fit supertight again at room temperature. I would not advise to heat the fitted barrel trunnion piece to speed up the locking action, rather let itcome back to room temperature slowly so the material can "work". When the trunnion & barrel are at room temperature, one should cool them both again and then heat them (100-200° C )up to make material stretch and fit for a strong lock, instead of firing it immediately.
ATTENTION: Be sure that you are able to place the trunnion right on the barrel within seconds. While you can heat/cool the parts when they are seperated, obviously this is not possible when they are installed. So removing this barrel again from the trunnion will require a hydraulic press for sure.