GD&T True Position Question

[Jason @ CPM Industries]

Does anyone know how to calculate true position from 3 hole datum's. I have attached a file that shows what the print in asking. I am knew to this and only know how to get the position from a X dim. and Y Dim.

Not sure how to relate all 3 holes. Thanks

[kh012]

your third axis or 'z' is basicly a perpendicular call out.

with the referance hole perficly level then the c/l axis of the other holes

must be inside of the dia .038 call out thru the hole.

without a cmm a quick way is to find the x/y locations at the top of all the holes

then repeat at the bottom of the holes all the locations must fall into .038 callout.

 

HTH Ken

[metalmansteve]

Also, the M stands for Maximum Material Condition.

The tolerance is .038 when the holes is at its smallest allowable dimension (13.005)

Your tolerance grows relative to the hole size. The larger the hole the more tolerance you gain.

[Jason @ CPM Industries]

Thanks for the help Ken. I am using a master3dgage cmm and I was reporting the true position of a circle but wasn't coming up with good results. Sounds like what after you are saying is I need to check it as a cylinder to pick up the top and bottom of the hole. That should work. Thanks again,

 

Jason

[generaldisarray]

http://www.engineersedge.com/calculators/spherical-true-position-calculator.htm

[crazy^millman]

Should give your dealer a call or Verisurf and let them do a gotomeeting to help you get the results you are after. With the Gage make sure you have nominals for the system to calculate from. If there is not wireframe then you could get bad results, because there is not the needed correct information for the calculation to come from.

 

Here is a topic I did for Verisurf that might help.

http://www.verisurf.com/forum/viewtopic.php?f=7&t=224

 

 

HTH

[Verisurf - Ernie Husted]

Jason,

 

If you're new to GD&T you can find a lot of good information here.

http://www.tec-ease.com/gdt-tips.php

 

Ernie

[kh012]

Thanks for the help Ken. I am using a master3dgage cmm and I was reporting the true position of a circle but wasn't coming up with good results. Sounds like what after you are saying is I need to check it as a cylinder to pick up the top and bottom of the hole. That should work. Thanks again,

 

Jason

 

yes you will need to measure a cylinder to define the axis of the hole.

as stated above the max. mat'l cond. is your friend to get more tol.

how ever much the hole is from the max. mat'l size you add that differance

to the dia .038 to get more pos. tol.

never used the mastergage but the software should calculate all these factors

 

added note: you will want to measure the cylinders in the same direction ie: bottom to top.

this will make the c/l axis directions all go the same way.

 

++11 on the tec-ease site i use it all the time

 

HTH Ken