I made a block (aluminum) that screws to the action using the bottom plate screw hole, and two set screws at an angle to engage the followers & retain the compressed mainspring(s) and followers.
Works nicely.
You need to make a push rod to use to compress each spring and follower deep enough so the set screw will jam the follower in the mainspring hole.
I set the whole thing up in a Mill/Drill using the vise to hold the frame and the quill to compress the springs. I can lock the quill in any position to hold the spring follower compressed
as I tighten the set screw.
But usually just hold the quill down and turn in the set screw with the other hand.
Simple enough but use some care in compressing the spring w/follower. Make sure the rod is squarely in line with the follower and spring and help guide it down into the frame a ways with a gloved hand/fingers.
The spring while initially being compressed w/the follower can kink suddenly to one side and the follower w/spring disengage from the pushrod. The parts go free & flying off into areas of the shop heretofore unkn.
Once compressed and held in place with the set screw, the push rod is retracted. The hammer is then dropped into the slot in the frame and lined up with the pivot hole. There is no spring tension on the hammer when doing this so the hammer can be pick up easily thru the side with a tapered punch and the pin started thru the frame and hammer to secure it and into the center section of the frame.
Then do the other side as well before releasing the spring tension on either side. Keeping the spring tension off of the hammer(s) allows the pivot pin to be easily driven into place.
