Back in May of 2015 I needed a replacement eccentric rod for an N Scale Rowa/MRC 2-8-4 Berkshire to replace a missing one on a second-hand locomotive, and designed and 3D printed the part. The post can be found here.
Since then I’ve had a request to provide a replacement bell crank for the Rowa/MRC 2-8-8-2 Y6B. This mighty steam locomotive was one of the original N scale greats dating back to 1969 when MRC first released it.
It went through a few changes and was re-released in 1977 by Con-Cor/Rivarossi.
One of the main differences in the two versions is the side rods and valve gear. The original MRC, and later Rowa version had plastic parts, whereas the later Concor/Rivarossi ones had metal. The part I’m replacing is on the earlier MRC/Rowa version, which coincidently is exactly the same on their 2-8-4 Berkshire.
The original Berkshire bell crank and eccentric rod are shown below. They simply clip together and the bell crank rotates about the round lug, which is at the other end from the C section.
The new 3D printed bell cranks are printed on a sprue, simply because they’re so small.
Up close you can see the new 3D printed part is slightly chunkier than the original injection molded part to give some extra strength to it. Once fitted it’s very hard to see the difference.
On the Berkshire, with the bell crank removed, you can see the circular hole at the back of the bell housing to receive the round lug.
The new part clipped right in and rocked back and forward with ease. The part will ideally be painted silver before the final install.
The original eccentric rod clips into the new bell crank and the main drive wheel, fixing with ease, and that’s it. This particular Berkshire has no motor in it so I can’t show it running, but it ran freely along the track by hand with no issues from the new bell crank.
The Y6B, as I said before, has the exact same bell cranks, just more of them.
The only difference is the eccentric rod is shorter, which is caused by the altered geometry of smaller driving wheels compared to the Berkshire.
A pack of 6 bell cranks for MRC/Rowa 2-8-4s and 2-8-8-2s are available here.
I’ve had some time to get around to finishing some other long overdue 3D printing projects and over the next few weeks, I look forward to sharing these with you and making them available to buy.
You must be logged in to post a comment.