Monday, May 21, 2012, 10:30 a.m. — I finally completed a rather rough (emphasis on rough) diagram with dimensions of the weight found on the Bunnell Gold Bug.
I thought the weight was rather ingeniously designed. Rather than sliding on a round rod at the end of the key’s main spring, the spring steel main spring extends the length of the key and is terminated by a brass base for the weight. The weight is attached to the top of this base, and slides forward and backward. The base of the weight is milled so it rides atop the base like a track; the adjustment of the weight is limited in its travel, but I found it pretty easy to add some additional range for the key’s speed.
A FEW CAVEATS. My measurements were made with a very, VERY inexpensive set of calipers which used 1/128th of an inch as the unit of measure. You will have to do your own conversions to metric or decimal. However, the drawing will get in the ballpark. As noted on the diagram, the rear of the weight is curved to match the base, which has an identical curve.
If I were going to make some of these weights, I would make a couple of different ones of varying weights. You don’t have the range of weight adjustment on the Gold Bug as you do with a Vibroplex.
I hooked my Gold Bug to my station and the key plays very well. The dot contact is a little dirty, making it sound a little scratchy; I’m just happy how well it played given its reputation for poor performance. Perhaps its the higher speed telegraphy that exposes its design flaw(s).
Good luck with reproducing the weights … I need to borrow a better set of calipers!
73