r/Metrology • • 5h ago

GD&T | Blueprint Interpretation Datum reference frame

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11 Upvotes

Not here for homework help.. Just raising a question because I think this book is just making stuff up at this point.

Bubble (A) is establishing Datum B .. but the position tolerance is using B in its datum feature reference frame. How is this possible for a feature to reference itself?

Any input? Never ever seen this before.


r/Metrology • • 8h ago

Standardizing cuvette conditions for measure leaf gas exchange (photosynthetis) : constant VPD or constant temperature and RH ?

2 Upvotes

I am currently measuring light-saturated net assimilation in leaves to study their photosynthetic compensation capacity in response to a reduction in leaf area. Measurements are done in the field, in a tropical environment, using a Walz GFS-3000. Also, the measurements aren't all taken on the same day.

I have tested two approaches for setting the cuvette conditions:

Approach 1: I fix the cuvette temperature at 30 °C and the relative humidity at 72%. Under these conditions, VPD varies from leaf to leaf (and plant to plant).

Approach 2: I adjust temperature and relative humidity to keep VPD between 12.00 and 12.99. VPD is then the same across measurements, but the relative humidities and sometimes the temperature used differ among the leaves/plants measured.

I am wondering which approach to choose: does keeping VPD constant by adjusting temperature and relative humidity, while having different measurement conditions (T and RH), risk introducing a bias in the comparison of net assimilation?

To compare leaves under conditions as standardized as possible, is it better to fix temperature and relative humidity and accept variation in VPD, or to fix VPD by adjusting both parameters? Is there another setting strategy you would recommend for this type of field measurement?

Thank you in advance for your help and suggestions,


r/Metrology • • 53m ago

TP20 module assessment of working conditions

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• Upvotes

Hi everyone! How can the proper functioning of a TP20 module be assessed?
Suppose a module sticks upon contact with a surface—this in itself indicates that there is an issue with the module. However, it is also possible for a module to appear to be functioning correctly while actually experiencing operational problems that go unnoticed by the operator.

How can one properly assess whether it is functioning correctly? Are there any tests for this?
The problem is that this can affect the overall accuracy and repeatability of the CMM.


r/Metrology • • 3h ago

Instron, UTM, Tensile Tester Software

1 Upvotes

I have viewed a lot of material about software upgrades for tensile testing machines. We have spent about 3 years developing a Software that can be put on almost any Instron or UTM as a DAQ but has Machine control built in for Instron 4000 series and Chatillon TCD models as well as a few more. It mosly is used for old chart machine frames that can be brought up to Windows 11. any machine that has external control such as up, down and has a speed setting, this software is exactly for that.