Share a Fact from Your Job

[14ledo81]

9 hours ago, Ernest Jones said:

If you eat an orange after lunch, no one will know that you're high. 

What do you do for work again???

[Lihu]

9 hours ago, Pretzel said:

The splinters are awful. I made the mistake of brushing off a part by hand once when I was still pretty new and I was digging metal out of my hand for ages afterwords. Always blow them off with air and properly deburr them before handling.

Or use a CNC mill with circulating liquid to cool things down. I generally use a brush because the air can blow chips over to the next machine. Air is good at the end of the day.

[Ernest Jones]

4 hours ago, 14ledo81 said:

What do you do for work again???

Guidance Counselor. 

[Lihu]

1 hour ago, Ernest Jones said:

Guidance Counselor. 

Well, depending upon the age group, I can't really say I blame you for eating oranges.

[Pretzel]

6 hours ago, Lihu said:

Or use a CNC mill with circulating liquid to cool things down. I generally use a brush because the air can blow chips over to the next machine. Air is good at the end of the day.

A cnc mill is good for many things, but is overkill for simple parts. I only needed to shave down about .75 inches of length and drill two holes into a piece of 7.125" round stock, so a cnc would've taken more time than it was worth to model in solidworks and set up, since I knew the dimensions for the holes and had a target weight since I was making this part for ballast (lots of little adjustments to the thickness of the part to get it correct).

Cnc would've been easier only if I knew the exact material of the part so I could model it with a correct weight in solidworks to create the NC code in mastercam.

[Lihu]

3 minutes ago, Pretzel said:

A cnc mill is good for many things, but is overkill for simple parts. I only needed to shave down about .75 inches of length and drill two holes into a piece of 7.125" round stock, so a cnc would've taken more time than it was worth to model in solidworks and set up, since I knew the dimensions for the holes and had a target weight since I was making this part for ballast (lots of little adjustments to the thickness of the part to get it correct).

Cnc would've been easier only if I knew the exact material of the part so I could model it with a correct weight in solidworks to create the NC code in mastercam.

Yeah, simple parts are easier that way.

I'm doing a lot with 3D printers as well. Many things don't need the precision so it's nice to print at my desk.

We're kind of spoiled, but automated rapid prototyping is becoming the norm. We design around accuracy limitations for convenience.

 

[Fourputt]

On 2/19/2016 at 1:52 PM, Pretzel said:

Interesting thing to note from my current internship with the NASA Space Grant program is that not all antennae are the metal rabbit ears that you may think of. For example, the antenna used in the satellite project I am working with is actually a composite material machined into what looks rather like a spear (and actually is kept covered with foam at all times when removed from the dish to prevent injuries). I can take an image of it probably by Monday to show what I mean.

On a somewhat related note, most people who've never been in a machine shop don't know how much of a pain (literally) steel can be to work with. When you machine the steel, chips of metal are removed from the part and are flung by the end mill. These chips, due to the fact that they were just ripped from the steel, are quite hot. They then fly through the air, often coming to rest on your arms or shirt, burning you and leaving several smoldering holes in your shirt if the chip is large enough and hot enough. Not as bad as welders who have to deal with dripping slag, but a pain nonetheless.

33 years as a journeyman machinist.  During my apprenticeship I ran a gear cutter that was built in 1863 (it was serial number 3 from a company that started in 1860).  It was once used to cut some of the original gears for the locks in the Panama Canal.  During my time in that shop I worked on parts as large as 50 tons for the mining industry.  

Later on for a different employer I ran several CNC mills, programmed and ran them.  I worked regularly to tolerances of .0003 to .0005 (that's 3 to 5 ten thousandths of an inch).

The company I retired from made the machinery that extrudes and print the labels on aluminum (and some steel) cans.  We were the world leader in can decorators.  Our 36 mandrel printer could print 2200 cans per minute in 8 colors with perfect registration (the can passes across 8 engraved plates, each of which applies a different color, and that requires perfect timing).  The tolerances we worked to were necessary to maintain that sort of accuracy.  Think about the speed in terms of an automatic weapon - the only thing I know of that exceeds that is a multi-barrel minigun.  The M-16 only hits about 900 rounds per minute max.  

I machined a lot of the parts for them and saw them run many times, yet I was still amazed watching the cans come off of that machine.

[DaveP043]

The engineers who evaluate soil conditions and design foundations really don't know what's going on in the ground.  We have amazing calculation techniques and models.  The problem is, we don't have any test methods that test the soils in the way they're going to be stressed under a foundation.  In addition, the soil changes both vertically and horizontally, so what we DO test is simply a small sample of the whole.  So we guess, and we estimate, and we average, and then we use correlations to past history, apply a big safety factor, and hope for the best.  Our saving grace is that all of the correlations have been based on worst-case scenarios, so the situation is almost always better than the basis of our design.

[Golfingdad]

2 minutes ago, DaveP043 said:

The engineers who evaluate soil conditions and design foundations really don't know what's going on in the ground.  We have amazing calculation techniques and models.  The problem is, we don't have any test methods that test the soils in the way they're going to be stressed under a foundation.  In addition, the soil changes both vertically and horizontally, so what we DO test is simply a small sample of the whole.  So we guess, and we estimate, and we average, and then we use correlations to past history, apply a big safety factor, and hope for the best.  Our saving grace is that all of the correlations have been based on worst-case scenarios, so the situation is almost always better than the basis of our design.

Everything we do is done this way as well.  I chuckle sometimes because I feel like we take some of this stuff a little too seriously given two of the factors you mentioned:  "big factor of safety" and "worst-case scenarios."

Quick example:  Many of our projects are homes with a basement garage that have a steep (20% slope) driveway leading down to it.  We design the drainage for a 100-year storm event and then many times one of us will just add 2 or 3 times as many channel drains across the driveway "to be safe."  We'll say, "well, it's steep and it's going to be slippery, so we don't want somebody walking on it to fall."  The I step back and think, "what sane human being is going to be attempting to walk down that driveway in a 100-year storm event?!?!  Further, how insane would that person have to be to not notice that it was wet and slippery?"

[14ledo81]

@Golfingdad and @DaveP043, the engineers call it "factor of safety".... The installers grumble about "overkill"…...   :)

[DaveP043]

2 minutes ago, 14ledo81 said:

@Golfingdad and @DaveP043, the engineers call it "factor of safety".... The installers grumble about "overkill"…...   :)

And deny ALL responsibility when something goes wrong.  "He designed it, not me."

I've actually told owners that they could do things cheaper, if they wanted to accept some risk.  Not many think that's a good idea.  They want the cheaper, and still want the designer to be on the hook if anything goes wrong.

[kpaulhus]

Did you know, that during the week of Thanksgiving, French's French Fried Onions is the #3 selling item in edible food (In the USA)

[billchao]

When a restaurant is unexpectedly closed for whatever reason, no amount of traffic cones, signs, nor general "construction site" appearance of the place will stop people from attempting to come inside and order food.

[Golfingdad]

14 minutes ago, DaveP043 said:

And deny ALL responsibility when something goes wrong.  "He designed it, not me."

I've actually told owners that they could do things cheaper, if they wanted to accept some risk.  Not many think that's a good idea.  They want the cheaper, and still want the designer to be on the hook if anything goes wrong.

Man, do I wish contractors/owners could read my mind sometimes.  So often I have to tell them on the record something that they need to do because of some asinine agency regulation or just some stubborn plan checker, and all the while in my head I'm just screaming "don't do this - just do it how you wanted to do it and nobody will know or care!!!"

Other times, I'm very, very grateful that owners and contractors cannot read my mind. 

[DaveP043]

Its interesting, I work for a ground improvement contractor doing a lot of design-build work as well as a lot of work to someone else's specifications.  Because we do this work all the time, we know a lot more than almost every consultant who writes the specifications for our work.  We're always fighting the impulse to tell the owners how little their design team knows about the work we do, and how much unnecessary cost they're requiring.  Hey, they're taking the liability, we'll do it in whatever way they want us to.

[jamo]

1 hour ago, Golfingdad said:

Everything we do is done this way as well.  I chuckle sometimes because I feel like we take some of this stuff a little too seriously given two of the factors you mentioned:  "big factor of safety" and "worst-case scenarios."

Instead of "big factors of safety" we call it "conservative design." It might turn out better than what we're accounting for, but it's definitely can't turn out worse. 

[ppine]

I had a contract with Peabody Coal on the Navajo Reservation for 6 years. We would go down twice a year for 10 day trips.  After work we would wander around on the Res looking for petroglyphs, dinosaur tracks, pottery and shards covering acres of ground. We found some old bows and arrows that are still out there.  We went into Kayenta for dinner some times and could hear the drumming and singing at the community center. Herds of sheep and goats would come by when we were working with a couple of dogs and no people. They would head home in the late afternoon. Once in awhile there would be a big band of sheep with a guy on horseback. We always stopped to chat with them.

Edited March 11, 2016 by ppine

[Big Lex]

On ‎8‎/‎30‎/‎2015 at 1:21 PM, iacas said:

I like weird little bits of trivia, so I thought I'd start this thread.

 

Share something - a fun fact, an interesting fact, something - that you know because of your job. Whether it's something like a civil engineer saying something like "when considering traffic for the construction or maintenance of a road, one semi truck counts the same as 50,000 passenger cars" or what… share an interesting fact.

The number of breast surgeries performed on women today is at least 5 times the number that were performed when I was in medical school 25 years ago. This is a huge increase, and it is an example of how costs continue to escalate in medical care.