Profile measurement question

[Burunduk]

What would be your preferred way of manually inspecting this profile tolerance?

 

[mfgenggear]

Burunduk
I would use a sine plate with a magnetic v block
On a surface plate. Sin plate kicked to 105 degrees. Dial indicater holder on a surface plate.
Slide dial indicater over the face while locating on datum-A- and -B-

An other would be same set up except CMM

 

[Burunduk]

mfgenggear,
Do you mean like that?

 

[mfgenggear]

Burunduk
precisely my friend.
the gage block for zero is dead on

 

[pmarc]

Burunduk,
In this setup, is the height of the stack of gage blocks used to establish the zero reference calculated based on the distance between the intersection point of datum axis A and datum plane B and the surface plate? Is the point-to-plate distance going to be maintained for the measurement of all piece parts (assuming there is more of them to inspect)?

 

[mfgenggear]

A quick calculation of the stack up would determine gage block setup.
Also a quick cad drawing would make short work.
Once this setup is completed. It is a very fast method to inspect a lot of parts.
I done it many times.
I can ad one two three blocks can aid in the location of datum B

 

[Burunduk]

pmarc,
I merely illustrated mfgenggear's suggestion as I understood it. I think yes, with the dimensions of the sine bar and the exact and constant placement of the pair of V blocks taken into consideration, it will be necessary to calculate trigonometrically the vertical height from the surface plate to the intersection point of datum axis A (center of the pair of V blocks) and datum plane B (the inclined top face of the sine bar). Can't tell the exact math right away, I'd probably check that with CAD. To that, I would add 35cos15° to know the height of the zero reference stack of gage blocks.

 

[Burunduk]

mfgenggear,
Thanks a lot for your advice and confirmation.

 

[pmarc]

pmarc,
I merely illustrated mfgenggear's suggestion as I understood it. I think yes, with the dimensions of the sine bar and the exact and constant placement of the pair of V blocks taken into consideration, it will be necessary to calculate trigonometrically the vertical height from the surface plate to the intersection point of datum axis A (center of the pair of V blocks) and datum plane B (the inclined top face of the sine bar). Can't tell the exact math right away, I'd probably check that with CAD. To that, I would add 35cos15° to know the height of the zero reference stack of gage blocks.

Got it.

One more question: Assuming the flat surface was manufactured exactly at the true profile (for this condition we know the measurement reading should be zero), how does this setup ensure that the flat surface is parallel to the surface plate?

 

[Burunduk]

pmarc, unless I'm missing something critical, this nominally parallel orientation is obtained by setting the sine bar's angle to 15° (can be done by piling the small stack of gage blocks shown on the right side in my illustration to the height corresponding to the opposite cathetus of 15° in a right angle triangle with the hypotenuse being the distance between the rollers). Obviously the accuracy of all the gage components in this set up will contribute to the measurement uncertainty.