Side Rods

Scale Details
A quick look at these pictures of 1501 and the the plans shows that the plans are nothing like the full size locomotive.

The ends are too large and the wrong shape. The scollop is on the wrong side of the rod too, and the rear boss should be flush with the rod face.

You can also see that the rods have a 'Fish belly' shape.

The detail at the knuckle joint is wrong too. There's a radius at the root of the forked piece and the tongue is flat across the back, not curved to match the rod end.

Of course none of this affects the running of the locomotive but it doesn't take any longer to make it look a little more like the real thing.

The diameter of the crank pin on the driving wheel is rather large as drawn, so it's not really possible to get it to look exactly like the picture.

Bearings


The bearings can be made of Phosphor Bronze PB102 which is suitable for running on Case Hardened mild steel or Silver Steel pins.

The bearings need to be a press fit in the coupling rods.

NB:- Sometimes bearings are made with the hole out of centre to compensate for errors in the centre distance.

Most bearings are plain with a single oil hole in the top and a small drill hole to feed it. The 3D model shows an alternative arrangement that gives a closer to scale external look with a larger oil reservoir. The bearing also has a groove around the outside to hold more oil which is fed to the bottom through a second hole in the bearing.