1979 >> April >> Threadless Corner The Stearns Insulator  

"Threadless Corner" -- The Stearns Insulator
by Ray Klingensmith

Reprinted from "INSULATORS - Crown Jewels of the Wire", April 1979, page 5

This month I decided to cover another insulator of the "threadless era", a patented item which, to my knowledge, has not been found. 

On November 26, 1869, Joseph B. Stearns, of Boston, Massachusetts, applied for a patent on an improvement in the method of attaching insulators to their supports. He was granted a patent on September 13, 1870. The patent actually involved two different, but similar, methods. I've included a copy of the patent drawing (see fig. 1-4), and have also made four drawings of my own (fig. 5-8) 

I felt the patent drawings might be a little confusing, and decided to draw the insulators and pins separately so that everyone could understand the invention a little easier. Sometimes the patent specifications get a little complicated, and this one certainly was no exception. The insulators and pins involved were designed with corresponding grooves and pegs in a way to lock the two together. 

In his first method, Stearns designed a regular threadless insulator. In the dome area was a small opening, from the outside area to the pinhole inside (see fig. 1 and 5). In this small opening was placed a small peg. Picture it, if you will, as a matchstick going into the dome of the insulator. Fig. 5 shows a cross section of the insulator with the peg (C) inserted. It projects into the pinhole a small distance. Figure 6 shows a pin (B) with a groove (D) the same size as the peg. To mount the insulator on the pin one would position the pin in a manner in which the peg (C) would enter the groove (D). The insulator would be pushed downward, allowing the peg to follow the groove. After traveling approximately 1-1/4 inches, the peg would reach another groove (E which traveled almost entirely around the pin. At that point the insulator would be turned in the direction of the groove (E) until reaching point (F), at which time it would be fully mounted. Notice the depth of the groove from E around the pin to point F gets shallower in depth. The pin is designed that way to cause the peg and groove to bind and become firmly joined, to prevent the pin and insulator from coming apart. 

In his other method, Stearns had the peg (C) embedded in the pin. Imagine, if you will, a threadless pin with a matchstick driven through its center, projecting from one side a small amount (see fig. 8). This pin would fit an insulator as shown in fig. 3 and 7. This insulator was a regular threadless insulator with a small groove at one side of the pinhole. This groove (D) started at the entrance of the pinhole and traveled upward to a point approximately one half the distance to the top of the pinhole. At that point the groove (D) joined another groove (E) which circled the center of the pinhole nearly the entire circumference. To install the insulator one would place the insulator in a manner in which the peg (C) would enter the groove (D). The insulator would be pressed downward until it reached a point where groove E is located. At that time the insulator would be turned almost one entire revolution, at which time it would be fastened firmly to the pin. The groove (E) on this insulator is also shallower at the far end, as was the groove in the other method. This allows the insulator to be firmly attached to the pin. 

This design seems very interesting and quite practicable. Had it been invented about ten years earlier, I'm sure it would have seen some use. However, the screw-threaded insulator was becoming popular at the time of the Stearns invention, so it's doubtful it was a success. Probably only a small number (if any at all) were produced. I know of none to exist; but as with many other patented items, it would be no surprise to me if one turned up. I'm a firm believer that if someone went to all the trouble and expense to have something patented, then they would most likely produce at least a small amount of their invention. 

As you are reading this, Spring will be upon us, and that means digging season. It really amazes me how few collectors have ever found even a piece of a threadless. The only way to find something is to look, look, look and look more. It's so much fun to try to find a rare jewel. Sure, many places have been searched before, but there are millions of insulators waiting to be found. Come on, grab that trusty, probably rusty (from lack of use!) shovel and get to digging. I've got my favorite digging places, many of which local residents told me time and time again, "Oh, you're too late. There have been a dozen collectors here before you." Well, that doesn't stop me. I'll find what they didn't find! Don't let the fact that other people have searched the area stop you. I've walked over 60 miles of one line, found some nice broken threadless, which involved a lot of scratching around, digging, sweating, aching muscles and hard work. It involved considerable time. And what do I have? Well, I have many fond memories of great times and experiences. I've many more friends, friends which I'd never have made if it weren't for my "diggin's". And, one of these days I'll find that whole threadless. In the meantime I'll be having a great time and getting some healthy exercise. 

Just thought I'd add that last November I took my sister with me on a dig. She always talked about going with me and finding a threadless. She had gone with me once or twice before, but it was more of a nature trip in the past. This time it was an insulator trip. The two of us hurried to our "site" and started digging. Of course I explained the "right" way to look. One must have that special technique, you know! I guess we had dug for a couple of hours when she started finding insulators, and I found ROCKS! First she pulled up a CD 126 Brookfield with the embossed date on the lower wire projection, then came a CD 126.4 W.E. MFG. CO. in an unusual icy green color, similar to a sage green California. Well, then of course came the top one third of an unembossed CD 736 threadless. Oh well, just a mere threadless!! So as you're reading this, the two of us will probably be out there looking for that whole one. Come on, folks, get in on the fun. Let's see what we can find!



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