Mechanical Calibration References

I salute your patience. I would have did completly ignore such an obviously "homeworkish" question.

Oh, you know some times i really asking myself what do I do here where the level is going so low.

I came on CR4 with the goal to help and give what I know to other and of course learn new aspects of engineering, but I am quite disappointed by the evolution.

Some times I have the feeling I listen to a group of oldies chatting and boasting it is not what I expect from an ENGINEERING group.

The threads and most comments are not creative and if an idea is brought then it is not analysed from the feasibility point of view, neither from a quantitative one it is only brought without any backing.

To give an example the last generator for participation was the spill. I saw a lot of "solutions" but without a logical background.

By the way what I am sincerely surprised is the fact that the "experts" from BP did not realize that methane + water + pressure will generate at the low temperature the blocking crystals! The cover as they put it was without any redundancy in case of plugging with any kind of stuff. It had not a possibility to clean the connection.

And I remember the 1st comment "let the experts do it". Quite special those experts.

I agree that we seem to be getting more elementary in the level of questions brought here.

But, there is still the occasional "good question" that holds my interest.

Don't leave. I know that when you respond to a question that you will always give a well reasoned, educated and technically correct answer. And we don't get too many of those any more.

Are you also bemoaning the fact that there are no good engineers left anymore? I hear that from senior guys all the time, but I am afraid thats just not true.. things were done better back then because they were perhaps simpler... Things are much more complicated these days..

No, not at all!

I only think that level of tuition went down and engineers - especially young ones- believe in computer programs more than in basics for making a model and analyse for optimization. There was an old approach I always was against: cut and try!

It is not any more valid since simulations did a lot of progress but for a good simulation one has to have a VERY good theoretical AND practical background. I have more and more the feeling it is not true in the majority of cases.

I know very well how thinks did evolute and became more complex but the means one has are also wider. When I started my activity gears were computed with same equations but with hand or electrical-mechanical devices and a corrected profile asked for days of work, now a hand calculator brings 12 digits of precision in fractions of seconds and a XLS sheet the whole result in a couple of seconds. I kept abreast with technologies and for giving you a feeling I am equipped with several CAD, CFD, and FEA programs and with mathematical soft since I consider our profession as a mixed one with theory and practice interlaced.

When I was at the beginning of my career I designed a hydraulic system to lift horizontal a platform with a non centred COG supported by 4 cylinders on a NOT plane ground with sensors and all controls with ONLY hydraulics and not using, as would be done today, electronics, sensors and proportional or servo valves simply because such devices were not available. And this -according to what you wrote - "simple" system - worked in all conditions (summer or winter) with an angular error less 0.25°. So that do not believe that years ago technique was simpler it was even more difficult if a high quality was requested. Do not make the error to consider "oldies" as "old stuff". I remember that you wrote that your attitude toward kinematics would have been different under other circumstances.

You have the same behaviour I had when I finished my study and became "engineer", I thought I know a lot and to be more advanced than some body who learned years ago - my father - and I came across a problem and did not know how to solve it, he asked me about what I felt concerned and in a couple of minutes gave me the optimal solution. I was a lesson I kept in the back of my mind for all may life till to day.

Nice sharing of thoughts Nick. I also do agree totally with you.

I defer

For all calibrations preferably we should go to primary units / primary standards. Basic units are force (weight), length, time etc.

Thus for Pressure gauges, instead of Pressure transducer, better to use Dead Weight Pressure gauge tester where force (calibrated weights) and the diameter of plunger (L^2) are the parameters of the reference. (F/L^2)

For Torque also, better to go for force and arm length. (FXL)

Cable tensioner and force gauges... only force (F)

Micrometer vernier I agree with you.

If primary devices for primary units (weights, dead weight tester, length reference) is not available, then only secondary devices (which are calibrated against primary) may be used.

Hello yemenia.

I must say I am a little confused. Since March of 2008, you have asked four questions of this forum, all relating to calibration of measuring tools, or techniques for their use.

Has the advice previously given proven incorrect? Are we answering the wrong question?

Signed, Furrowed Brow in Fargo.

If "calibrate" means "list on customer's test documents that calibrated equipment was used" then you might need to use a calibration lab with appropriate certifications." Having calibrated tools/instruments and being able to sign that calibrated tools/instruments were used are two different things.