Switch Handle Page

The original PDP-8/E switch handles. The picture is blurry, but does a good job of capturing the orange-brown shade of the darker handles.

Another try. This one gets the yellow shade better. A kind of mustard yellow, with a hint of green.

Another picture of the original switch handles.

This is the first replica that I cast. It is yellow, but the saturation is wrong, and the hint of green is missing, though you can't tell that from the photo. Notice that this is the "down" side when it was cast, so there are very few flaws (introduced by trapped air).

Here's the other side of the first attempt. Here you can see some largish pockets of air where there should have been plastic. These air bubbles naturally float to the "top" of the mold.

Here's another attempt, this time for the darker shade. Although when cast, it looks quite dark, you can see that it hardened to a lighter (taupe) color.

The other side. Again, a few trapped bubbles of air. None of the trapped bubbles affect the function, but you'd have to decide if the cosmetics were acceptable.

Another try. This was actually trying to darken the too-light yellow color. The result is a kind of peach color.

Again some minor issues with the top side, quite serviceable.

Now some pictures of the hinge detail. This picture is dark, but you can see that I got the hinge detail to come out in this version.

Here's the flip side (much brighter) but the hinge detail is there.

Same thing, but a little sharper. This is the latest attempt, with the latest modifications to the mold (to deepen the "cups" that form the hinge pins).

Back to the first attempt. Neither hinge tab came out, so I have drilled through for a pin.

The flip side of the same thing.

The second casting, with one good hinge tab.

The other side, where air was trapped in the mold, preventing the hinge pin from forming. This must have been a surface tension thing, since the air would have risen, if it had escaped the "cup" in the mold that forms the pin.

I have made a first attempt at a mold for 14 switch handles, which would be enough to make a complete set of handles in two castings (one for each color).

I suggested I could make RL01/RL02 drive select keys, because they have a simple shape, and don't need the added coloring. I believe any bubble defects can be kept small and confined to the non-cosmetic areas. (Basically, if I can get the hinge tabs to come out, the larger pins on the drive select should be doable.)

Last updated on 04/30/12 02:07