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Confessions 24

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D Scullion

D Scullion

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Sep 1, 2016
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Many interesting links shared detailing other peoples screw ups. Anybody on here willing to admit to their own?

Not trying to entrap anybody, don't admit to anything you could still get prosecuted for. Just want to hear a few funny stories.

I'll start: My first job in a small engineering firm with very little senior experience, almost every day was a near miss:

- Prototype 24 ton dump trailer, my first folly with hydraulics, on placement from uni. I designed the small hydraulic rams that open and closed a gull wing style back door to operate on the same circuit as the very large rams that lift the 24 ton laden body, without any flow controls. On first operation the back door closed so hard and fast it damaged the solid steel door.

- Ordered a laser cut sheet steel kit for a first production batch of a new product. Didn't realise AutoCAD was set so that all files were scaled 10:1. Received a delivery of miniatures.

- Made a tolerance error on the pivot of a large arm that moved a prototype piece of machinery into operating position. It seized up so tight only the hydraulic ram on the arm could turn it, couldn't even get grease into it. Prototype was on a tight deadline for a demonstration in front of a large group of customers which we had to go ahead with. Started to move the arm and the screeching from the pivot was mortifying. needless to say we waited until everyone had left after the demo before folding it back in again.

 
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My latest was a measuring error.
I recently acquired a newer truck to pull the rodeo trailer (3 horse trailer with living quarters).
I thought it would be a good idea to have a socket on-board to fit the wheel nuts. I pulled out the new, bargain caliper that I had bought a few months ago and not yet used.
30 mm wheel nuts.
The next time in town I bought a new 30 mm socket.
Didn't fit. That was a first. I had never in a long career seen a socket far enough off of the marked size to not fit.
But, you know, things are going to hell all over these days.
A few weeks later I was at a friends place and borrowed his sockets to check. Wait, his 33 mm socket fits?
When I got home I took a close look at my new caliper.
The scale was printed 3 mm offset from where it should have been. All measurements come out 3 mm short.
I guess that's why it was on sale cheap.

Bill
--------------------
"Why not the best?"
Jimmy Carter
 
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Had a boss from Europe who did the conversion from metric to english for his height for his driver's license and came out 9 feet tall.

Same boss had us fabricate a stainless steel backsplash for his kitchen that, per his hand sketch, was 2"x3" - we gave it to him in a picture frame with the caption under it "Check Your Units"

We had a bonafide rocket scientist working for us (it was a gig after he retired from his real job) and he wired a digital clock to battery switch power, so every time the vehicle was power cycled the clock would flash 12:00 and need to be reset. He went back to the schematic and sure enough that was how he designed it. "Huh, how about that" was his reply. When he did retire from the company I sent him a thank you email with an animated flashing 12:00 gif and cc'd the department
 
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I mentioned this on the tower settlement site.

I may have caused the settlement of the Millennial Tower. In the late 60’s I was a concrete inspector for BART on the Lower Market Street Station, near the Tower. As you know, the station was constructed using soldier pile/slurry concrete walls. The slurry walls were used as both water cutoff walls and as the actual structure walls, a first at the time. While I watched the pours along that side of Market, just beyond where Millennial Towers is now located, I was also watching a gorgeous woman walking along Market Street. I think I watched her too much and missed some bad concrete that was placed here. And is now leaking and allowing the Tower to settle. I married the girl and we ran away to N.Y.

 
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Well, you got the girl and had a hand in creating a future landmark. I think this is a win all round.

------------------------------------------------------------------------------------------
If you can't explain it to a six year old, you don't understand it yourself.
 
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You're just bragging now.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF
 
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Aussiejohn2,
I guess that name would fit too. The patternmakers called it an expansion rule because it was bigger than the standard rule and was pre calculated to allow for the fact that the pattern had to be that much bigger to allow for shrinkage when the iron cooled . So your name of shrinkage rule is a bit after the fact.
B.E.


You are judged not by what you know, but by what you can do.
 
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Confession:
I designed a power supply/relay board for refrigerated rail cars. It was part of a system to save Union Pacific $2M a year in fuel costs by forcing the Detroit 3-71 to an idle when the temperature setpoint was achieved.

It was a simple board that had a custom transformer, caps, rectifiers, and relays on it. We mounted it in the big electrical control panel associated with the generator and refrigeration controls. I built it on a nifty aluminum L. It weighed about 3 pounds. Unfortunately I had the board on the horizontal part of the L.

Everything worked just peachy in a month of testing in the rail yard and out in the fleet. Yay! We promptly cycled a hundred cars thru the Watsonville yard installing our fuel saving kits in the cars.

BTW: Never park with a rail switch lever unit directly behind your truck as you can't see them in any mirrors...
316wvna.gif


Anyway about 5 months after releasing all the cars out into the wild my boards started coming back... stinking with huge carborized gaping holes blown thru them. After getting about 5 back I figured out that there was a bunch of metal dust raining out of the contactors above my horizontal board. It took months for it to build up until it conducted, heating up things until the board literally toasted.

My boss said, "Fix it!"

I came up with a conformally coated board mounted vertically. This solved the problem except the cars were scattered to the for corners of our great country..

My boss said, "Go change them before they lose a railcar full of avocados or cured hams". (200,000lbs of them)

So I found myself in Seattle Washington, in the rain; Pocatello Idaho, in 2 feet of snow (midnite); Salt Lake City Utah; Jacksonville Florida, Dallas, El Paso, New Orleans Louisiana, and about 5 other places I'd never heard of, asking people, "Have you seen a refrigerated railcar around here?"



Keith Cress
kcress -
 
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I designed a pedestrian bridge with 8 in. square tube columns at a 20 ft spacing along each edge. The roof was a translucent barrel vault arch system that had a thrust that pushed the tops of the columns apart. To counteract this, I added a small turnbuckle and rod system to hold the columns together. When they were installing the rods, the turnbuckles were sagging down a few inches. They tried to tighten them, but the rods pulled the tops of the columns closer together. I just eyeballed that the catenary-like force would be small, so didn't run any numbers. Boy was I wrong. We had to ditch the rods and turnbuckles scheme and change to a small steel tube that held the columns the correct distance apart.

On one project, I designed a composite spandrel beam that twisted so that the edge of the slab was an inch or two low. The overhang was 15 in. and the spacing to the first interior beam was very small, so the bulk of the load was on the outside. I think they also had a shear tab connection, which didn't help matters. We had to add a topping slab near the edge to result in a level surface.

I had other situations in which stuff wouldn't fit together, but these two actually failed to some extent.
 
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Ha Rod. About, I'd guess, 2% of my handle.
I made a college senior project that was an intricately designed electronic apparatus that was carefully designed to self-disassemble over time in synchronization with my oral description of its function. It was carefully crafted and worked perfectly as capacitors exploded, MOVs smoked, and transformers fried.

As a high school student, with my crazy life-long friend, we did tons of destructive testing in his mad shop, lots of which let smoke out. Speakers hooked to the mains. Motors run under water. A display stand based salt water rheostat which we could modulate the voltage delivered to all the houses on our block with, etc., etc.

One especially memorable test was when we clamped a helicopter magneto in out bench vice and drove it with a large motor as fast as we could. Just as we peaked the speed/output the high voltage lead got loose and landed on the ancient workbench surface covered in grease and impregnated with metal filings and dust. The 3 dozen blue arcs that instantly appeared everywhere on its surface lit that sucker on fire instantly.

Finally I was kicked out of Eng-Tips 4 times (I have absolutely no idea why) and so was getting kinda cavalier about my usernames by the time I got to this one.

Keith Cress
kcress -
 
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Yeah, itsmoked, I had a few projects in my garage that turned out similarly. As my sound tech mentor kept telling me about electronic components, letting the smoke out is bad.
 
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One of the other posts reminded me of the time as a graduate I had some steel diagonal angle bracing under a timber floor. I had long vertical gussets full height of the supporting girders for two beams framing out the braced floor bay that were running orthogonal to two larger steel floor girders at roughly mid span. I had detailed some short vertically orientated gussets for the diagonal brace with two bolts orientated vertically. These gussets were recessed right into the beam web/beam gusset intersection. All looked good on paper at least.

Turned up on site and the contractor had sliced a 20mm wide piece of plate out of the bottom flange all the way from the edge of the girder to the web, because there was absolutely no way that they could get the diagonal brace in past the full height gussets and the beam flange. Cutting the slot allowed him to lift the brace into position with no issues.

Once I discovered it, he proudly pointed out the fact that he had solved the issue without involving me. Much to my annoyance they had never asked, and never even pointed it out to me until I noted it myself on site.

Suffice to say I learned a few things that day around detailing/constructability and also fixing on site issues. Never done anything like that again. Always think about how someone is going to build what you draw.

 
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How many of us have flipped up the welding helmet to discover something is on fire?


No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF
 
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Agent; I was very surprised to see a bunch of ~6 inch I-Beams in a new wood house construction by my house about 2 weeks ago. Today I went by and was surprise to see they'd filled in all the contours of the I-Beam with wood, even the flanges!

Keith Cress
kcress -
 
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I haven't had any spectacular failures, however there has been the occasional tolerance stack error mistakenly applying LMC or MMC when the other condition should've been used. I've never not had parts fit together, but I have sweated in front of techs a time or three. For me its always the little things, never the engineering that is flawed.
 
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Spar web,
Been there got the tee shirt.
At one job I was doing, I discovered that the burning smell was coming from my beard.
About three very energetic seconds later it was out.
B.E.

You are judged not by what you know, but by what you can do.
 
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We had an apprentice who set fire to his coveralls. He put the fire out and went back welding. There was some pain but he expected that and kept working. The pain got worse. Finally he stopped welding and discovered that he had not put the fire completely out and he was still on fire. He was burned badly enough that he was on light duties and on crutches for a time.
And if that wasn't bad enough, a few months later he managed to set fire to his prints. He wasn't welding. I was afraid to ask what he was doing. He may have been smoking in a restricted area and stuck his cigarette in the prints to hide it when he heard someone coming.
I'm guessing but it's an informed guess.


Bill
--------------------
"Why not the best?"
Jimmy Carter
 
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Wow Bill.

Reminds me of a vivid episode in junior-high metal shop. The teacher, Mr. Streeter, had us all around while he pulled a yellow hot crucible of molten aluminum out of the furnace during our casting phase of the class. I don't recall what caused it but a dollop of aluminum slopped out of the crucible while he was holding it in long tongs and the dollop went right down the inside of his right boot.

To this day I am very appreciative of his spectacular grimace, loud involuntary gurgling sound he make, and the slow care with which he set the crucible down before screaming and ripping his boot off.

Keith Cress
kcress -
 
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