F7b Drive and Underbody

Well, as I continue to work to get the F7b back on line, I took the drive and tested it on a straight track. The engine kept jumping off. As I looked at it, I could see that one truck was skewed up and to the right. Something in the truck was out of line. So, I disassembled the truck and found that the bolster screw was bent, Probably, from the drop to the floor. I slowly tried to straighten it but it snapped. You can see the brass screw less any threads. The silver screw was used to determine the thread pattern.  Needless to say, I did not have a replacement, so a project is in my future. 

Fortunately, I have a lathe so I can make a screw. Taking a brass rod of sufficient diameter, I turned the end down to a shaft that I can cut a 3X0.5MM thread on it. 

Taking my threading die, I carefully cut the threads on the shaft.

I then test it on the truck bolster and it spins right on. Part A of our problem solved. Now I have to address the shaft through the bolster pad.

Now I turn the bolster shaft to the dimension of the original screw. Next, I get to cut off the blank with the same sized head. Part B is done.

Here is our blank with no slot to turn it with. It is sitting next to the original screw. 

I need to remove the tang from the cutoff and reduce the thickness of the head slightly. Part C finished.

Done! Now I take it to my mill and, using a saw blade, I cut a slot into the head so it is really a screw. I also reduce the length of the threaded portion to match the original screw. 

Finished screw. Time elapsed - about 2.25 hours. So, using the Government's accounting approach - this is a $50 screw. But, then, I did not have another one, so I am happy to have it. 

I reassembled the truck and ran the chassis on the layout. It was solidly on the track and ran well. I am a pleased railroader. Now, back to the body and finishing of the painting, adding a lighting circuit and reassembly.