The Little Switch, Part 2

Ordinarily I prefer to complete things, such as kit assembly, start to finish; the continuity allows me to remain focused. On this occasion, however, breaking the work up has helped me to approach each of the main components with a fresh, clear mind. So, for example, I was able to tackle the frog without being drained from the effort of modifying and assembling the roadbed.

Before getting down to business, I added the last roadbed connector to the frog area, where the connectors overlap a little. Having slept on the problem (a process, incidentally, that's been clinically proven to be a very real, measurable effect), I devised a way to squeeze in a modified connector:

The frog I'd designed in my mind long before I went to work on the switch. It consists of five parts: four sections of rail all tied together with a piece of .035-inch thick nickel sheet metal. I determined the geometry of the sheet metal part right on the sheet by positioning the rails on it and marking it with a sharp knife.

Using a jeweler's saw fitted with a very fine-tooth blade, I extracted the Y-shape from the sheet metal. A jeweler's saw is quite difficult to control precisely, so I cut the part just slightly oversize; I then carefully ground down to the marks using a Dremel fitted with a diamond cutoff disc.

Next, I chamfered the bottom edges to clear the rail base. This allowed the part to fit snugly against the rail webs. When the part was precisely shaped, I secured it and all of the rail parts, upside down, to a scrap of PC board for soldering. Solder was applied liberally to fuse all of the parts into one solid piece. The assembled frog was then trimmed down and sanded to make all surfaces even and true.

The next step was to devise a method of attachment. I decided to take a fairly direct approach: I drilled and tapped a hole for a 00-90 screw in the middle of the large area at the heel of the frog. An electrical terminal on the underside will allow the assembly screw to deliver power to the frog as well.

This brought me to the close of the second work session. As tempted as I was to press forward with the points, I decided to set the project aside once again; the frog was relatively painless to fabricate, and the result was so successful that I didn't want to put my streak of good fortune at risk. I did, however, test-fit the switch on the layout once again to ensure that everything was still in alignment.

At the risk of repeating myself, I must say this thing is small. It's not as if I hadn't noticed this before; it just becomes ever more apparent as I make each new component. It'll be interesting to see how much it winds up looking like the actual product.

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