After taking a few days off to do a video for the upcoming Gauge IO Guild Virtual show I returned to fitting the motion on the 8F. True to form it continues to entertain and frustrate in equal measures.

I started by fixing the links between the Drop Link, Union Link and Combination lever together with the pins and retaining washers that I made previously for the task.

It was once I had these assembled that I realised that once fitted in place the crosshead travel in the slide-bars was being limited by something and as it was it wouldn’t allow a full revolution of the wheel.

This was the limit of the forward travel. Initially I tried a bit of filing of the combination lever to see if that would allow it to move further forward.

This didn’t make any noticeable difference and I came to the conclusion that it was the fit of the combination lever in the “valve block” (? – I don’t actually know what this part is called)

This is what I came with the kit and I had drilled out the hole which was cast as a dimple on the centre line. I concluded that the hole for the retaining screw was too far forward causing the front of the combination lever to hit the lower front edge of the valve block causing the travel to stop at that point this conclusion was born out when I took it apart because one of the valve spindles had bent under the pressure.

I had also enlarged the side openings in the valve guide castings to allow better fore and after movement of the retaining screw.

Having reached that conclusion I decided rather than try to drill out the existing valve blocks and potentially wreck them that I would make some replacements that were a little longer so that I could set the hole further back.

As is my usual practice these days, I measured the castings that I have I modelled it in 3D.

From there I created a working drawing

At this point I decided to make one to test the theory. If successful I would then document the second one.