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Mechanic vs Mechanical Engineer

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I'm sure you've heard this story 100 times. Basically, my friend and I got into a BIT of an argument about the purpose and use of mechanical engineers and mechanics. My friend who is a mechanic, works at this factory and managed to modify this machine to make it run better/ more efficiently...and essentially got to the point where he said mechanical engineers are just overpaid mechanics (as he could easily improve this machine), and that they got their chins up high thinking that they're better than mechanics.

 

Naturally I tried to explain what mech. engineers do. Then he said "why do you need dynamics, statics, or calculus if a mechanic can fix and make this machine better than what some &$@%&! mechanical engineer can do !"...in a very unhappy tone.

 

This is where my side of the argument began to fell apart, mainly because I've never taken an engineering course (I'm biochem), or understood why engineers need to take such rigorous material. Does my friend have a point though? Do mech. engineers receive higher salaries than mechanics because of a piece paper they got? I dont think he is, but I'm not sure why.

 

-Thanks,

 

~EE

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My Grandad once talked about this subject. He was an RAF Airframe and Engine Fitter (mechanic) on bombers from 1936-1972. In a nutshell he said mechanics just do it and engineers can design it ...this is the principle difference. His son was an Oil Project Manager (Engineer) and a scenario for him would be that he was told there was oil in say 7200 feet of water before hitting the seabed and he had to tell the oil company what they needed to execute the task and understand the geology so they would know the drilling equpment needed when they got there. Engineers can deal with the novel but mechanics can't ...generally. My grandad was quite capable of and had designed stuff but never called himself an engineer because he said you needed a degree. The dividing line is blurred somewhat but on the whole I agree with him. Professionally, it's about training.

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Let us say you ask a mechanic or mechanical engineer to fabricate a yacht deck mounting or cleat.

 

The mechanic could go to the metal store, obtain marine grade stainless and make a perfectly satisfactory fixing, possibly a more serviceable one than the engineer could manage.

 

But suppose further that you want it made of some new marine resistant material, then you would need the extra capabilities of the engineer to redesign the shape and size to accomodate the new material properties.

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A mechanic may have learned engineering or good design through a given degree of his own successes and failures at it. Some will even have what appears to be a natural ability to do this successfully. They may have paid extra attention to details of design that most other mechanics have not and through this have had few errors of their own making.

 

But engineering is about being as close to 100 % successful in critical systems like buildings, bridges and aircraft as can be had. Trial and error is not as efficient in money and lives spent as is a careful and educated analysis of design.

 

The decade before the Wright brothers success comes to mind, many mechanically inclined individuals died or were crippled at the controls of their creations.

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But engineering is about being as close to 100 % successful in critical systems like buildings, bridges and aircraft as can be had. Trial and error is not as efficient in money and lives spent as is a careful and educated analysis of design.

 

Do you know about Limit State Design?

 

:)

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Do you know about Limit State Design?

 

:)

Thanks to you and Wiki I do now. :)

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The most noticeable difference is under their fingernails.

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The most noticeable difference is under their fingernails.

And the scars on my knuckles. ^_^

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To me this is quite clear and I always like to use wikipedia's definition to make the distinction clear

 

"An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics, and ingenuity to develop solutions for technical, societal and commercial problems. Engineers design materials, structures, and systems while considering the limitations imposed by practicality, regulation, safety, and cost."

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Late to the thread but the answer to this question that I've always liked is thus....

 

Anyone can build a bridge that stands, but it takes an engineer to build a bridge that *barely* stands.

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An engineer is someone who can do something for sixpence that any damn fool can do for a shilling.

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I liked answer 10 so far.

 

A carpenter can build and repair a house, but it takes an Architect to design the house.

 

A mechanic can build and repair an engine, but it takes an Engineer to design it.

 

The Architect must calculate weights, structural supports, and even evaluate the soil (Consider reports).

 

The Mechanical Engineer must calculate piston circumferences, Metal stresses and much more than a mechanic when designing the engine.

 

An Engineer is capable of design or manipulating the machines in their care.

 

Imagine you were the department of defense and you bought a new truck. Would you want to hire a $65k/year mechanic to maintain it, or a $90k/year Engineer. The answer is a mechanic because most cars have been engineered down to the last nuts and bolts.

 

Now imagine you (same department of defense) were buying a $20 million dollar Prototype self driving car. Would you want the same mechanic overseeing the project? No. This is because the machine is both very expensive, and it needs to be streamlined and improved over time. Each succeeding prototype needs to be smaller, faster, and more efficient than the next, and require calculations of various motor stresses and strengths along with many other self driving related equipment such as cameras and software.

 

In the last situation though it would be a mechanic normally repairing the vehicle but would follow Engineer suggestions regarding all new self driving equipment.

 

The Engineer can calculate the strength of every bolt, or cast metal/plastics in the project, but the mechanic can only screw them together.

 

It sounds like your friend is servicing a rare type of machine that is still in some need of development. A regular mechanic would be fine once all the bugs were worked out, but he should consult with an Engineer before modifying the machine. Imagine a well meaning mechanic filed down an Engine block to reduce the weight of the car. WoW; the car runs so fast.... Until the Engine explodes and everyone gets killed. Who goes to jail then? The Mechanic or Engineer?

 

But many Engineers may also describe themselves as overpriced Mechanics, especially if they are performing mechanic type duties on a unique machine. It is because the machine is requiring improvements. I can go one better. I am a soil Engineer so must have helpers and myself drive to various locations and stake out drilling locations, property inspections, and land title inspections. I tell people I am a glorified driver because I am in my car half of the time, and half my wages seem to be gas reimbursements+. I send everything to labs and do not need to even handle the soil (except in containers for mailing), and everything I write is sent to an editor. Yep. Glorified Driving is fun...

Edited by barfbag

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Your friend is implying (perhaps indirectly but the same nonetheless) that a mechanic, with no mathematical or scientific background, would be able to design a manned space vehicle. A mechanic can fix things, but how did they learn to do this in the first place? The Engineers do not just hand over a complex machine and say "ok guys, you figure this thing out." Mechanics are great because they can adequately service machines consistently.

 

However, does that mechanic have the knowledge to evaluate the geometry of the machine and construct shear and bending moment diagrams to find stress maximums? Can that mechanic use calculus to discover the area of a complex surface that is needed to find the area moment of inertia? Does this mechanic even know what a force vector is (the basis of all stress studies) and how to break it into components? I doubt it.

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An engineer is someone who can do something for sixpence that any damn fool can do for a shilling.

Just as tom_riddle said, can a mechanic evaluate the geometry of the machine, find stress maximums, and break force vectors into its components for analyzation? No, they can't. I'm beginning to think mechanics who complain about engineers are just wannabe engineers who couldn't hack the intense study and commitment and decided to replace valve covers and fix transmissions instead. These particular mechanics think ther engineers owe them b/c they maintain and MAYBE improve their designs, when in reality without the engineer's presence every car coming off the production line would be improved relative to how the driver died in it.

I liked answer 10 so far.

 

A carpenter can build and repair a house, but it takes an Architect to design the house.

 

A mechanic can build and repair an engine, but it takes an Engineer to design it.

 

The Architect must calculate weights, structural supports, and even evaluate the soil (Consider reports).

 

The Mechanical Engineer must calculate piston circumferences, Metal stresses and much more than a mechanic when designing the engine.

 

An Engineer is capable of design or manipulating the machines in their care.

 

Imagine you were the department of defense and you bought a new truck. Would you want to hire a $65k/year mechanic to maintain it, or a $90k/year Engineer. The answer is a mechanic because most cars have been engineered down to the last nuts and bolts.

 

Now imagine you (same department of defense) were buying a $20 million dollar Prototype self driving car. Would you want the same mechanic overseeing the project? No. This is because the machine is both very expensive, and it needs to be streamlined and improved over time. Each succeeding prototype needs to be smaller, faster, and more efficient than the next, and require calculations of various motor stresses and strengths along with many other self driving related equipment such as cameras and software.

 

In the last situation though it would be a mechanic normally repairing the vehicle but would follow Engineer suggestions regarding all new self driving equipment.

 

The Engineer can calculate the strength of every bolt, or cast metal/plastics in the project, but the mechanic can only screw them together.

 

It sounds like your friend is servicing a rare type of machine that is still in some need of development. A regular mechanic would be fine once all the bugs were worked out, but he should consult with an Engineer before modifying the machine. Imagine a well meaning mechanic filed down an Engine block to reduce the weight of the car. WoW; the car runs so fast.... Until the Engine explodes and everyone gets killed. Who goes to jail then? The Mechanic or Engineer?

 

But many Engineers may also describe themselves as overpriced Mechanics, especially if they are performing mechanic type duties on a unique machine. It is because the machine is requiring improvements. I can go one better. I am a soil Engineer so must have helpers and myself drive to various locations and stake out drilling locations, property inspections, and land title inspections. I tell people I am a glorified driver because I am in my car half of the time, and half my wages seem to be gas reimbursements+. I send everything to labs and do not need to even handle the soil (except in containers for mailing), and everything I write is sent to an editor. Yep. Glorified Driving is fun...

Yea, you're actually right. My friend "enhanced" some large turntable machine that should have been out of commsion years ago..kinda like using a DOHC instead of a SOHC...the knowledge for the improvement was fundamental and present, it just took someone to get off their lazy rear to actually do it...and because he did this he thinks he's the next James Watt...oh lard!

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Late to the thread but the answer to this question that I've always liked is thus....

 

Anyone can build a bridge that stands, but it takes an engineer to build a bridge that *barely* stands.

Yes, engineers understand quantitatively the limits of the properties of the materials available to them.

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Late to the thread but the answer to this question that I've always liked is thus....

 

Anyone can build a bridge that stands, but it takes an engineer to build a bridge that *barely* stands.

 

String Junky

Yes, engineers understand quantitatively the limits of the properties of the materials available to them.

 

 

 

@String Junky

Sometimes. Hopefully more often than not.

 

@Inigo Montoya

Having done some failure investigations in my time I have little sympathy for an Engineer who designs a bridge that barely stands.

Such a bridge would not satisfy any code that I know of.

Edited by studiot

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Having done some failure investigations in my time I have little sympathy for an Engineer who designs a bridge that barely stands.

 

 

 

I had thought

 

Anyone can build a bridge that stands, but it takes an engineer to build a bridge that *barely* stands.

 

 

was one of the best (and concise) answers so far.

 

Having done some failure investigations in my time

 

 

Understandably sad and potentially horrific.

 

 

However just because an Engineer designs a Bridge that Barely stands does not mean it was not built to last 100 years or that could not meet strong Earthquakes head on.

 

Those would be the Engineers that make a bridge that does not stand.

 

It is sorry to hear your experiences (last post), but as long as the bridge stands for a long time under all conditions, then the Engineer did a fine job.

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Barfbag,

 

Since you were interested in my last post (#16) I will expand.

 

Firstly the quote as I remember it was due to the builder of one of the NewYork bridges and went

 

An Engineer is someone who can build (make) something for $1 that any fool can build (make) for $2.

 

Which is different from barely standing.

 

 

As to bridges and their design, the bridge has the longest formal design life of anything made by Man. This design life is 120 years, though some have stood for more than ten times that.

 

When an engineer designs a structure she considers a great many other factors besides what is known as 'The limit state of collapse'.

A structural design is judged against a set of limit states to provide

"A quantifiable and acceptably low probability of failure against any of these criteria"

 

This method replaced the older 'factor of safety method' of design.

 

Statistics plays an important part in the design. I will explain further if you like.

 

Anyway the most usual failure for structures is not collapse, although that does unfortunately happen as in Tacoma Narrow and Lodden Vaiduct, but failure of what is known as the

"limit state of servicability"

 

This means that although the structure does not fall down or become unsafe, the deflection under design load is excessive.

 

A good recent example was the London 'wobbly bridge' that was too flexible

 

https://www.google.co.uk/search?hl=en-GB&source=hp&q=london+wobbly+bridge+video&gbv=2&oq=london+wobbly+bridge&gs_l=heirloom-hp.1.1.0l2j0i22i30l3.828.5594.0.10703.20.18.0.2.2.0.265.2845.0j7j7.14.0....0...1ac.1.34.heirloom-hp..4.16.2922.MoPMxhmZDOk

 

One main purpose of the limit state of servicability is to limit deflection in floors/ceilings so that finishings such as plaster or tiling does not crack.

 

;)

Edited by studiot

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An Engineer is someone who can build (make) something for $1 that any fool can build (make) for $2.

 

 

Is also nice, but as a cliche I liked the bridge version if taken with salt. It describes well the job in the briefest way possible, but I am sure nobody wants a bridge that barely stands (unless its floating, cough!).

 

Speaking as an Engineer who will never build anything except models in my spare time. I just play in the muck.

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