Do Not Assemble

"I see. I hadn't correctly divined your attitude towards your tenants." — Monty Python

[Product Design for Manufacture and Assembly]

I have uncovered yet another evil plot. In a day and age when product designers are encouraged to make things easy to assemble, certain things continue to be difficult. Design For Manufacture and Assembly (DFMA) is a formal body of knowledge that provides design rules to assure ease of assembly, among other things. People write books and they teach courses on the subject. Magazines write articles on it. I have written an article on it!

Most of the rules for easy assembly are simple. Your assembly should be a base that sits stably on a table, or in a fixture. Your parts should retain themselves in place while you attach fasteners. You should make things snap in place so that you don't need fasteners. There should be adequate finger clearance around the parts.

[75 Ohm connector] Consider the humble 75Ω connector, known officially as an F connector, used mostly for cable TV, and antennae. The threads are 3/8‑32UNEF. The photo shows two of these things in the back of a VCR, in a pocket with not enough clearance for fingers. I was able to tighten them with an open-end wrench. I do not think an adjustable (monkey) wrench would have fit in the space. It helped that I have sets of SAE and metric wrenches. It did not help that there was not much room to turn the wrench. I lost count of the number of wrench engagements and turns it took to install and tighten these things.

[SVGA connector] [SVGA connector inserted] [SVGA connector and fingers] Here is an SVGA plug I am connecting to my LED TV. The plug on the cable is a DE15P size D subminiature. Fortunately, I do not need to use this thing, Both of my external devices use HDMI connectors. I am in charge of photo slide shows for a ski club and I have experience connecting to SVGA ports on TVs. I have not yet encounted a TV with an accessible SVGA receptacle. In addition to the pockets, these usually are located at the bottom, in the middle, behind the mount feet. LED TVs are expensive and tippy, so you don't want to be messing around behind them.

The pocket this SVGA connector sits in, is not long enough to accomodate the rather large backshell. There are screws on either side of the plug that retain it in the receptacle. There is minimal room around these for fingers. A lot of the screws on D-subminiature backshells have screwdriver slots, but not these ones. If it did have screwdriver slots, you would have had to fit the screwdriver around the TV's mount base.

The cable TV F plug (white cable) is very difficult to acccess with the SVGA connected.

[HTMI connector] Here are my two HDMI plugs on the side of the TV. These are smaller than the SVGA plugs, but the backshells still are bulky. They are, however, accessible, as they do not sit in a pocket. There is a minor aesthetic problem with the one of the cables extending outside the side of the TV. There are RCA receptacles on the bottom and side of this TV, but they are small, and the plugs slide on without turning. Since this TV is not subject to impact and vibration, there is no problem with the slide-on HTMI and RCA plugs coming off.

Why do the black helicopters hate SVGA and cable TV connectors? Are these connectors evil? Are the people who use these connectors evil? Maybe the black helicopters are evil, and SVGA and cable F connectors are pure and virtuous. That would make the HDMI and RCA connectors evil. Why were we not taught this in college?