Sunday, March 3, 2024

Harp Stand Build

 Harp stands were the way for switching track mid 1800's. These of course were known as stub switches, the most common turnout configuration until point switches were created.

I had installed a 3 way switch about 10 months ago. My initial throw mechanism was an Arduino. Unfortunately, although it worked, knowing how to program it was WAY outside my wheelhouse!

Necessity is the mother of invention, as the saying goes. And I had more than necessity; I had HIGH need. This is a key area for my operating plans. I decided to use or build my own harp stand. First choice was the PCS hand throw. Al Mueller built one to operate. Unfortunately this stand is good for only a 2 way. I'd need to convert my rail from code 83 to 55 to make that a possibility. That was out of the equation as I had close to 200' of track. Build the harp was the most obvious possibility.

Using the PCS stand as the idea, I did a crude drawing, guessing the size needed. I went with about O scale to give it the length to reach across three rails.


Fabrication of the throw bar positioning cap was a critical build. Overall, my build came with a lot of luck as I measured only the distance the headblock would need to travel to ensure the fly rails reached the outer stock rails.

Initially I used a tri-corner file to start the cut for each of the three slots to hold the throw bar position. 

Next I used a razor saw. With a cross cutting motion I sawed the edges as well as the depth. This gradually created the tree openings large enough to hold the piano wire throw bar.  

Fabricating the legs and frame required 2 sizes of KLM angle brass stock. Angle was chosen for greater stability. The way to bend the angle is to make a notch which reduces an awkward bend and a cleaner angle in the leg.  

A quick touch of solder and the two legs are secured. The other half has been built and secured.

Spacers were inserted to ensure clearances for the headblock and throw bar movement as the reinforcing side panels were secured. 

Here is the Arduino servo that my friend Ray Russell built and helped me install. Unfortunately, however, the programming was too technical for me which led me to build the harp. 

The image below shows the harp installed and I am shiming the base, made from flat brass stock.