Can you explain what that means ?
Is that something like someone saying ' they proved the null hypothesis ' ?
Something by definition they have done wrong if they are doing that ?

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

My definition of "Mechanical Feel" translates to my trade as this...

Detail drawings in ACAD are generally done in a "3 view drawing", meaning 3 sides of the part are shown, so someone is able to machine the part and make it to print.

A "Datum" is a point on the part, usually a corner, where dimensions generate.

Someone who has no "Mechanical Feel", or mechanical experience will use multiple datums to dimension from for each view...meaning they will have some features dimensioned from the left side, some from the right side, some from the tip and some from the bottom. When this is done, it creates more work for the person machining the part, because they have to re-dimension the part to make it easier to machine.

Therefore, when someone lacks the "Mechanical Feel" they lack the experience to properly draw a part. They may be able to draw, but they cannot draw it in such a way that it can be made properly.

I hope that's clear as mud.

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1987 560SL
85,000 miles

I see your point as far as what you consider a datum. On ASME drawings you genrally have three datums, for Geometric Dimensioning and Toleranceing. Basically, you are dealing with a three dimensional or Cartesian cordinate system. So, usually two or three datums are needed. 'A' is usually the base, "B" locates in the 'X' plane or a hole and 'C' clocks the part or keep it from rotation. Mating surfaces usually have another datum. Usually, your dimensions come from 'B' or 'A'. On some parts, dimensions will be from another datum or feature. That signifies or keeps say bolt holes related to that feature. A good example would be bolt holes for a starter boss on a flywheel housing
Tom

For clarity purposes, I'll explain it as such...I'm an old school tool and die maker. I use manual machines to produce parts as needed for my projects, mainly because my employer is too cheap to buy newer machines. Our machines were state of the art in 1980...LOL

Anyway, when running holes spreads, I work off of one X,Y datum, or "0", if you will. The prints we are given, quite often have holes dimensioned from different surfaces. Holes on the left side of the part are dimensioned from the left edge, and the right side from the right edge, instead of having a corner as the datum. To produce it as dimensioned would add to the time to produce the part, because you would have to zero your read out a multitude of times.

Dimensioning it from one edge means you have one starting point, and all numbers come from that one point.

This is why I request part prints and such to come to me on a disk...I'll take a few minutes to re-dimension it in such a way that it's faster to produce. Other people don't care to think that far ahead in advance to find an easier way, and IMHO, take too long on the part.

Perhaps it's due to my years of experience in management and design that I try to find the easiest and best way to draw and dimension the part, because I know the information that the tool maker needs to produce the part.

I just call it common sense...do your job in such a way that the next guy down the line in the process can't make a mistake.

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1987 560SL
85,000 miles

well, there was my rock star wannabe co-worker, who told me that the shop-vac was "broken", because it was blowing out air?

and then said we had to turn the "water main" off, to change out a toilet. (how can you be 40 years old and not know what a shutoff is?)

and my israeli friend, who believes that copper pipe and galvanized pipe are easily connected - dielectric unions are a big scam - yet wondered why all his water pipes were corroded and leaking?

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"The law, in its majestic equality, forbids the rich as well as the poor to sleep under bridges, to beg in the streets, and to steal bread."

My father is a highly educated, well spoken gentleman; unfortunatly mechanically declined. I once drove 60 miles round trip to repair his mower........Yes it was out of gas.

I have a friend who should have his meager tool selection confiscated. He "gears up" for his automotive repairs with a pint of Johnny Walker. I cant begin to enumerate the amount of **** he has utterly destroyed.

I done some construction inspection for TARGET stores. You would love them. They have had it with plans that have too many dimensions on them---when they make a change, there are too many places where they have to change that dimension, and all the others that would now conflict. So they dimension everything only ONCE in the drawing set. You may have to search for it, bit the dimension you need is somewhere in the 30-40 sheet set of drawings. But when they revise the location of a wall by 6 inches, they only change the dimension; not the drawing.

Very intelligent on their part, IMO.

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

in high school I had the wires wrong on a chevrolet starter, I cranked it and the starter did not disengage. my mom didnt bat and eye and said "you turned the key to hard"

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1982 300CD Turbo (Otis, "ups & downs") parts for sale
2003 TJ with Hemi (to go anywhere, quickly) sold
2001 Excursion Powerstroke (to go dependably)
1970 Mustang 428SCJ (to go fast)
1962 Corvette LS1 (to go in style)
2001 Schwinn Grape Krate 10spd (if all else fails)