Our latest Build 11 work session was held on July 15-17. Quentin Bethune brought the eccentrics back from his home shop where he had finished machining the interior surfaces. That’s a lot of steel in Quentin’s truck! On top of this load you can see the fixture Quentin designed and fabricated at home.

This fixture is used to precisely locate the center of the eccentric on the lathe so that the outside circumference can be turned.

Each eccentric pair is mounted on the fixture twice – once on each eccentric face. The raised hub locates the cylindrical surface that will mate with the driving axle; the tall pin registers the tooling hole in the eccentric half. The tapped holes are used to secure the hold downs. And the 4 notches are pry notches. This is a fine example of the behind the scenes engineering that propels our progress.

Let’s go back in time for a moment – Quentin’s provided working photos from his shop. Once Quentin brought the castings home he took them to D. S. Greene Co. in Wakefield Massachusetts to remove a substantial amount of material to get the pieces close to our final thickness.

Quentin was able to program his home CNC mill to cut matching profiles in each eccentric pair. This critical interface contributes to an extremely precise fit of the eccentric halves.

The resulting pieces are shown below. Quentin added a small tooling hole to aid in alignment when turning the eccentric pair in our lathe.

After this step, Quentin drilled, tapped and bolted the halves together. He then brought all the material back to D. S. Greene Co. to finish the material to final thickness.

The eccentric ridges can be clearly seen in the following image. Quentin elected to stay an additional day beyond the work session to complete all 4 eccentrics – to avoid breaking down his setup and reinstalling it on a following work session. And we’ll bet you can’t see the beautiful profiles when the halves are joined together. Quentin estimates he’s got more than 100 hours in machining these pieces for the Build 11 project.

Harold Downey and Rick Sisson used our horizontal mill to drill and ream holes in the lead truck frame and swing link pins to accept taper pins. Each taper pin penetrates the lead truck frame casting and swing link pin, preventing the pin from turning and potentially loosening.

And, finally, Harold and Rick applied Epifanes two-part epoxy primer to the lead truck components. We expect this primer to provide a durable, long-lasting undercoat.

It may be hard to discern, but all the lead truck components are visible in the following photo.

The lead truck wheelset looks pretty good in its black primer. It will look even better after the color coat (a close-as-possible match to “Baldwin Green”) is applied in an upcoming work session.

…and thank YOU for giving 111% to this project! In 2025, our friends and followers have donated an astounding $134,775 towards Build 11 – 112% of our $120,000 goal (for 2025.) All additional funds will be used to ensure the locomotive is on the rails as quickly as possible.

Learn more and contribute at www.build11.org