I've been meaning to get out the T-square and triangles for quite a while. It's been years since I've done any sort of mechanical drawing. So, today I decided to draw a favorite old compass of mine at a scale of 1:1. The compass is an oldie with a large air bubble in it, but I got a lot of use out of it growing up hunting and hiking. I pulled dimensions from it, using dividers and calipers. The process of dimensioning to the nearest thousandth of an inch reminded me a lot of when I used to inspect parts for an engineering firm in Baltimore. While drawing, I realized how rusty I had gotten. I also remembered how easy it is to cut corners and rush through an area. This always results in a sloppy drawing and I didn't succumb to doing it. My lettering in particular leaves a lot to be desired and makes my drawing look as though a first grader had made it. So embarrassed am I, that I have hidden the drawing in this link. The good thing is; now that I've drawn, I'll continue to do so. I can only get better, and hopefully gain back the skills I lost over the years.
I really enjoyed measuring each aspect of the old compass. It has a lot of character. It's a simple design and incorporates a safety pin into its hinge. Through years of carrying it, I thought I knew it very well. Although while measuring the knuckles of the hinge I realized that the knuckle spacing on the bottom plate of the compass was not symmetrical. I wondered why, for a moment and then realized that this allows the safety pin to be completely concealed and not stick out beyond the top and bottom plates. Moreover, one could assume that a large part of the very design of this compass was based upon this standard safety pin being used as the rod in the hinge. The inner diameter of the knuckles were designed to accept the outer diameter of the pin. The knuckle spacing was designed to capitalize on the "grip length", if you will, of the pin so as to mitigate side to side play within the hinge. I know people think I'm strange already but this sort of thing is exciting to me. That's some clever ingenuity and I value it in all of the random old objects I pick up.
Feeling nostalgic for high school days gone by, I played a few Rush albums as I drew. Rush was well before my time, but it was one band that I really listened to a lot of in high school where I took my mechanical drawing classes. Some of the songs I played, I hadn't heard since back in the day. 2112 is still my favorite Rush album.