Saturday, March 19, 2016

The Most Terrifying Phrase in Engineering: All You Gotta Do

I think that's so old a joke that every engineer, technician, mechanic or other person who actually does things has heard it.  It's right up there with, "what could go wrong?"

Before the antenna project was completely wrapped up, there were just a couple of things that had to be done.  The system uses a 2x4 to clamp the tower to the house bracket.  The 2x4 has two 1 5/8" holes cut in it to go around the tower legs.  It's pressure treated pine, but even that goes bad eventually, so I had to make a replacement.  Over the 25/26 years this system had been in place, I've done this a handful of times, and I know the drill.  I take the old one off, trace the layout of the holes for the legs on a new piece of 2x4, cut the holes for the legs out with a hole saw, then duplicate the placement of the small holes.  One set of holes is for the bolts that hold the wood to the angle iron house bracket, the other is a smaller set that passes lag bolts that hold the clamp together. 

All you gotta do is make a new one and put it up.

I did that Thursday morning, so all that was left in the afternoon was putting that in place and cranking the tower up.  I waited until it was past the hottest part of the day (it was in the upper 80s this week) and then the comedy of errors happened.  First, I swapped it end for end when I put it up.  You should have seen the cloud of Looney-Tunes style question marks over my head when I first got the tower back vertical and the legs didn't line up with their cutouts.  OK, all I gotta do is crank it back down, and turn the piece end for end.  No big deal.  Only the two bolts I used to attach it to the house bracket were 18-8 stainless, as all of my project has been, and one of them galled.  More like self-welded.  It took a half hour and every tool in the house but by using a half inch drive ratchet on one side and a half inch drive breaker bar on the other, I was eventually able to shear the 5/16" bolt off.  Now I flipped the board end for end and replaced that bolt and nut (I bought spares of everything) and rebuilt it with Teflon grease, which is supposed to help with galling.  Cranked the tower back up; this time it fit.  Put it all back together and got everything done for the next few years. 

This is a somewhat sloppy drawing.  I suspect that a couple of dimensions and angles are bit off, but it looks something like this (from above and to the left).  The 2x4 is in brown.
All's swell that ends swell, but it sure was a three Advil night. 

Friday, while cleaning up some mess I made Thursday and getting the shop ready for the next project, it occurred to me that I should check the antennas electrically to make sure I didn't barf something up.  I have a piece of radio test equipment (an AIM4170) that allows me to measure the quality of the antenna match over wide frequency ranges.  While not exactly the same as previous plots, they were close enough for me to think it was just the different environment from the last time I tested; dry season vs. rainy season.  Then I tested the other antenna I have, one that I didn't touch and didn't even get close to, except for the buried coax that goes to it.  That one is way off.  Once the passing rains are over, a bit more antenna troubleshooting and repair is in the future. 

All I gotta do is make some measurements, and decide what went bad.  What could go wrong? 


  1. Off topic but I thought you might enjoy this one

    1. You're right. I really enjoyed that.

      Readers, it's a great story about education and the educational establishment vs. one little girl and a father that won't back down.

    2. That's awesome. The comments, however, are depressing. Apparently, "you know what I meant!" is considered the correct response to a bright student who gives an answer that doesn't match the rote, government - mandated response, regardless of that answer's correctness. Yay. Gods, I hate public education and standardized tests!

  2. I always use a generous amount of anti-seize compound on stainless hardware.

    Otherwise it will gall, usually resulting in the bolt head shearing off when you go to take it apart.

  3. Spent twenty hours of overtime plus regular time troubleshooting a valve group last week and still no closer to a solution when I was relieved by another co worker.
    What could go right?


    For the next time you have galled fasteners. It even works on galled stainless. It ain't cheap, but it's worth it. I still have one of the three cans I bought about eight years ago. Ended up giving the other two away to people who now swear by it as well.

    1. Seriously - bless you, Mark! I'm going to order some of that somewhere today and have it on hand.

      I also had one of my stainless cable clamps gall on me earlier in the week. It was easier to work around because all I had to do was pull the cable out of it and put a spare in its place. I think a can of this will be worth its weight in silver eagles.

    2. I found out about that stuff a few years ago when I was trying to unbolt the exhaust system from my car's headers. The stainless nuts had galled on the bolts, and wouldn't move. I walked across the street to see if my neighbor had a nut splitter, so that I wouldn't have to try to grind them off (no room for a hacksaw). He pulled out a can and suggested that I try it. I didn't think it could possibly work, but figured I'd at least give it a chance, since I wasn't looking forward to grinding away overhead. Sprayed it on and waited five minutes like it said. Went back out and put a wrench on the first bolt, and nothing moved. Was about to give up, but decided to try another one of the bolts for the heck of it. Surprise! It came right off! Four of the six came off with the first try. I sprayed some more on the remaining two bolts, waited another five minutes, and they came off as well. Of course, all the bolts and nuts were stainless.