Methods in Measuring Angles or Checking Angles for tools?

[Edgarf]

I have a tool that needs angle to be calibrated,i have attached a simple drawing.
Can anyone give their ideas on checking angles for tools?

I've tried calculating the measurements in reverse,although i was able to get the angle,I want to know how the experts do it.

Thanks for replies.

 

[Stijloor]

Use a sine bar.

 

[bobdoering]

CMM, optical Comparator, Sine Bar or angle blocks...just depends on the budget and availability. Biggest problem? Getting your 10:1 resolution at 0.01 degree. Need to measure at .001 degree. That is incredibly tight. I guess it is about 4 seconds (angular) resolution.

 

[iamtroll]

If you really mean calibration and not just measurement, you would probably use an autocollimator and also the angle surface for flatness with an optical flat.

 

[bobdoering]

The digital protractors from Insize only have a 0.1 degree resolution. Even those are not "good enough".

 

[BradM]

What about mathematically calculating it?

http://easycalculation.com/trigonometry/triangle-angles.php

As long as you can measure the linear portions with sufficient accuracy, that may be an option.

 

[bobdoering]

It is best to you can measure directly, if possible. You eliminate possible calculation error. Every calcualtion and additional measurement step is a potential, additive probability of cause for error.

 

[normzone]

Out of curiosity, does the application require this degree of precision to develop the end result as desired, or is the nominal and tolerance a result of having an available stockpile of decimal places?

 

[BradM]

It is best to you can measure directly, if possible. You eliminate possible calculation error. Every calculation and additional measurement step is a potential, additive probability of cause for error.

That's true. Good points.

However... sometimes we take what we can get.

I had a task of verifying a tool once with lengths and angles. I didn't have the correct equipment to accurately measure the angles. I could measure the lengths fairly accurately. It wasn't the best process, but it sufficed.

 

[David-D]

I tHink the first question that really needs to be asked is how big is the part? Is it 1 inch? 1 foot? 1 mil? Depending on the size/scale its going to be a significantly different problem. Also, what is the shape of the tool? Rectangular (w/ a flat reference surface)? Round/cylindrical? I'd think it makes a big difference trying to make the measurement. Also, for all the accuracy being called for, I'm a bit surprised it isn't specified with GD&T.

David