DIAL INDICATOR MADE WITH OLD MANOMETER!

[machining 4 all]

The main function of a dial indicator is to center and align surfaces. So, this project works in the simplest and most practical way possible!

[machining 4 all]

[machining 4 all]

Idea never seen on this forum, agree?

[Toolmaker51]

The main function of a dial indicator is to center and align surfaces. So, this project works in the simplest and most practical way possible!

Not to disagree, DI's operate to detect variances, centering and alignment fit that description. As your adaptation proves, this usage is one of repeatability, not accuracy, distinctly separate interpretations of position. It is possible to attain one, both, wrong or none to coincide.
l, ;
Mechanically, the manometer dial is correct. One drawback has contact not perpendicular to movement, introducing sine error. That detracts accuracy more than repeatability. Extending the lever arm ratio [increased point to axle vs axle to dial] would make this extraordinarily sensitive, reading extremely small increments, or 'resolution'. Again that is distinctly not same result as 'repeatability'.

For elevated levels of inspection, used in proper conditions, DI's are made capable detecting increments of .00005 [fifty-millionths] and less.

[machining 4 all]

Toolmaker51, thank you for your interest and comments. As soon as possible, I intend to carry out comparative measurements, to try to relate the reading of the manometer with the actual reading of the dial indicator (if there is, of course!). Of course, the purpose of this project is not to replace the dial indicator, but to create a cheap alternative to perform the centering of a surface, since the mechanism of a dial indicator and a pressure gauge have similar characteristics. I hope it is clear that there is no interest, at least in principle, in the nominal value of the eccentricity, but in the location of its position on the surface (basic use of this instrument). I will try to post the results here, soon.

[Toolmaker51]

Understood. Applauding the utilization of similar action entirely at odds with original mechanism. I'd think adjusting ratio making dial increments approximate .001, qualify this capable of your intent.
You might be aware of an indicator from way back, before watch-like designs, entirely lever operated. One great example is the Starrett No 64; not only one, just easiest to look up with results.

[machining 4 all]

I understand your concern and I should just add that unfortunately I don't have original factory tools at hand. My optimism always leads me to believe that the null hypothesis H0 will be a manometer = dial indicator with limitations.

[Hans Pearson]

Interesting idea. A larger scale movement would be easier to see. I wonder how a hydraulic cylinder attached to a low pressure gauge would work? (I made a unit along those lines to test the force of presses etc.)

[machining 4 all]

Hans Pearson, thank you for your interest and comments! Probably a greater movement of the pointer could be obtained by moving the point of rotation (fulcrum) of the lever. This is a physical principle taken into account, at least when analyzing forces. However, as there is no scale with smaller divisions on the manometer (as this instrument does not have this function) I believe that this project is particularly useful to fulfill the basic function of the dial indicator, that is, to find the eccentricity point to be modified. I made some measurements varying the contact pressure, I will post here soon and we will see if there is a consistent relationship between displacement and pressure. Your idea can be promising, develop your line of reasoning and if you find something, share it with me.

[machining 4 all]

After a few measurements, the results follow. I inserted five eccentric displacements at three different pressures. It can be concluded from the graph that, under less pressure, the pointer has a linear displacement. As pressure increases, displacements become more unstable and not proportional. Probably at higher pressures the pointer was more sensitive to surface roughness, and at lower pressures it was not as accurate. However, the ecentricity points inserted were identified by the manometer and it was possible to center the surface. Thus, it can be said that this assembly fulfills its qualitative function and is a low cost option when there is no dial indicator for any reason.