Calculating Perpendicularity

[cclaerbo]

I am using a laser tracker which will not automatically calculate perpendicularity as a cmm would. I can calculate an angle between two planes for instance, but do not know what equation I would need to use to calculate the error of the angle as an amount in thousands of an inch.

I need to know the math behind calculating perpendicularity between two surfaces.

Thanks

 

[ctopher]

Does this help? Or maybe be more specific?

http://www.easycalculation.com/analytical/perpendicular.php

http://biodiversityinformatics.amnh.org/open_source/pdc/documentation.php

Chris
SolidWorks 09, CATIA V5
ctopher's home
SolidWorks Legion

 

[KENAT]

Assuming you know the length of the face, it should be simple trigonometry.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

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What is Engineering anyway: faq1088-1484

 

[dingy2]

I agree with Kanat as long as the perpendicularity is not shown in GD&T. In that case, it combines angle and flatness (could be straightness) of the surface and trig won't help.

Dave D.

http://www.qmsi.ca

 

[KENAT]

Good point dingy, if the CMM has worked out it's angle from an averaged face that may affect results.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[sheevaraam]

-take two points on each of two perpendicular faces. Using the coordinates of the two points you can calculate the slope of the two lines.
-By taking tangent-inverse of the slopes you will get the angle.
-Then you can calculate the difference between the two angles and see if they are perpendicular.

 

[PaulJackson]

Take perfect spherical surface like a ping pong ball divide it exactly in two and fixture the edge of one of the spherical segments perfectly perpendicular to a slab surface. Now measure the perpendicularity of the inner spherical surface to the slab surface.

What is its value?
How would you measure that using a laser tracker?

Paul