#### ndfightingirish1971

##### New Member

- Joined
- May 14, 2013

- Messages
- 6

I am currently dealing with a problem that I cannot seem to find any information for. Here is a screen grab of the feature control frame. I realize that the FCF may look odd to some GD&T users, however, I do not wish to debate the accuracy of the FCF to ASME standards. I only need help with the composite portion of the FCF. This is not my engineering drawing and the customer is unwilling to change the FCF.

I have a spreadsheet that uses the following formula to attain the true position of 0.0200 to A, B, & C: =2*SQRT((A7*A7)+(B7*B7)+(C7*C7))

A7 is the deviation in the X direction, B7 is the deviation in the Y direction, & C7 is the deviation in the Z direction. I have another series of formulas that establish MMC bonus tolerance and a formula that uses an IF statement for "PASS" or "FAIL". The formulas all seem to work accurately as I have confirmed the numbers using an online calculator, as well as, my CMM software.

Here is where I need help. I am trying to write a series of formulas using PLTZF (Pattern Locating Tolerance Zone Framework) and FRTZF (Feature-Relating Tolerance Zone Framework) that will determine if the pattern of holes is accurate and I have no idea where to begin. I cannot find any mathematical formulas for hole pattern true position. As a general rule, I measure products on the CMM but in this case, the supplier is sending me raw data from manual measurements and they need help reporting the data. Any assistance would be greatly appreciated!!!

Thanks!