Screws and Couplings for USS Texas BB-35

[David2011]

We don't know what these are called and since they haven't worked in recent history, the function is not yet fully understood. They have something to do with either the elevation sight trim or motion limits on the 5 inch/51 caliber secondary guns on the battleship. We did know that major repairs were needed. First is one straight off of the gun during disassembly. The big wedge was rusted into the large casting but once it was out the screw came out of the wedge easily. That really surprised me.

The one that's primed in white is fully repaired.



The screws all had to be replaced. They're 1-1/8 x 7 left hand threads. After a lot of searching one of the employees found some 36" all thread in the right thread for a measly $200/stick. Three sticks were needed. The larger diameter feature was part of the screw on the originals. I made these .0015" undersized on the ID, heated them with a propane torch and let them shrink onto the area that I had cut down for the purpose. Each screw had to be cross drilled at a precise location at the blue mark on the right end.



These are the six completed screws and part of an original. I expected this one to be rusted solidly into the wedge but like the others is unscrewed easily. The work was cone on a Grizzly G9972Z which only has a little over 1" bore so all of the work had to be done with a steady rest. It was very time consuming to constantly have to reset the steady rest and re-measure from the reference surface.

 

[David2011]

There's a small coupling/universal joint on the right end of the screw in the first post. Some of them were damaged and had to be replaced. This was by far the most complex pieces I had ever attempted. I started by making a CAD drawing of the bodies. Somehow I made an error on the drawing and wouldn't you know it, the parts matched the drawing perfectly. Not sure how I ended up making round parts asymmetrical in a CAD program. At least I machined them to my own specs! New drawing, try again and they came out as expected. After this photo was taken I went back with a 1/2" ball nose end mill and removed the ridges inside the ears.



Satisfied with the coupling bodies, I started making the "balls" which I had been dreading. I decided to try to gang machine them. The material is 12L14. While I ended up with usable balls, they would have been better had I only attempted to make one at a time. The bore down the centerline of the round stock drifted a little but not enough to remake them.




The balls were parted off and deburred. I used 1/4" music wire for the pins. It was pretty hard on hacksaw blades but it miked at the right diameter. The holes in the balls were reamed .001" under and the ears on the couplings were reamed .001" over. I made the pins to their finished length and pressed them in using a vise. A letter D drill bit filled the holes perfectly so I put the shank of the bit into the holes to prevent pressing the pins in too far.




Red Loctite was used to help secure the pins in the balls. The surface finish isn't great but by the time they're bead blasted and 8-10 mils of primer plus paint is applied it won't matter. If these ever move once in place the movement will be very slow, as in counting the RPMs and timing with a stop watch. The holes had to be placed to align with the holes in the screws. They will be reamed for taper pins once installed.

 

[David2011]

I got excited and pressed the pins into the first one before rounding off the corners of the ears. Had to grind and file them down without dinging the ball. I didn't machine any of the rounded corners; not worth the effort. The thick paint will hide the grinding marks. They're using a coating system that has held up in the weather for at least 30 years so it's not like automotive paint.