True position Formula

[Shelia Moser]

Can anyone tell me what the formula is for True Position? For whatever reason this engineer thinks that the true position should have a bilateral tolerance. ( print calls out true position of 12) The engineer thinks that it should be like a profile point and be +/- 6.

[MIKEY]

hahahaha, DUMB ENGINEERS.

[John Kingston]

This thread.

This site.

Such a helpful answer there Mikey.

[Paul Sarrach]

Can anyone tell me what the formula is for True Position? For whatever reason this engineer thinks that the true position should have a bilateral tolerance. ( print calls out true position of 12) The engineer thinks that it should be like a profile point and be +/- 6.

Well is it a Diametrical True position? Then no, if it does not have a Diametrical symbol then yes it is plus or minus 6.

x(dev)^2+y(dev)^2+z(dev)^2

(x(dev)*x(vector))^2+(y(dev)*y(vector))^2+(z(dev)* z(vector)^2)

[Paul Sarrach]

This thread.

This site.

Such a helpful answer there Mikey.

John I thought the same thing, only I think I said " WTF?"

[John Kingston]

Well is it a Diametrical True position? Then no, if it does not have a Diametrical symbol then yes it is plus or minus 6.

SQRT(x(dev)^2+y(dev)^2+z(dev)^2 )

SQRT((x(dev)*x(vector))^2+(y(dev)*y(vector))^2+(z(dev)* z(vector)^2))

FIFY, forgot the square root.

[philwell]

He's half right. In your case the TP would be a circle with a 6 radius centered at the theoretical center of you feature, per your print. So if your x dim is 100 and you y dim is 100 then you TP circle center would be at x 100 and y 100.
And the center line of your feature would then have to be inside the circle

[John Kingston]

I like Phil's description. Draw a 6 inch radius circle. Draw a 12 x 12 square using the same center. The square represents a +/- 6 inch tolerance zone. The circle is the 6 inch TP zone. See how much of the square falls out of that zone? Show the engineer.

[John Riggins]

(squarerootofxdeviationsquaredplusydeviationcripes iwishtheywouldputtheignoreuseroptionbackineffecton thisforum)

[John Kingston]

(squarerootofxdeviationsquaredplusydeviationcripes iwishtheywouldputtheignoreuseroptionbackineffecton thisforum)

whydoyouwanttoignoremeandithinktheyfixedthatoption

edit:theydidifixthatoptionjohn

[John Riggins]

whydoyouwanttoignoremeandithinktheyfixedthatoption

edit:theydidifixthatoptionjohn

icantseemtofindtheignoreuserfeaturewhereisitexactl y?

[John Kingston]

icantseemtofindtheignoreuserfeaturewhereisitexactl y?

clickonUserCPtheignoreoptionisintherecheckyourpmIs entyouamessagehthereIamhavingablasttypinglikethisa ndthebeerhasnothingtodowithitdoyourealizehowhardit istotypelikethiswithouthittingspace?

[Darin Steiner]

true positionpythagorean

If you are measuring something in XY plane for example the formula for true position is: The square root of ("X" deviation from nominal squared * "Y" deviation from nominal squared)*2. It's the pythagorean theorum*2.

[mdobb829]

Can anyone tell me what the formula is for True Position? For whatever reason this engineer thinks that the true position should have a bilateral tolerance. ( print calls out true position of 12) The engineer thinks that it should be like a profile point and be +/- 6.

I know PC-DMIS still uses TP, but technically as of ASME Y14.5 -1994 it is no longer called true position. It is just position, and it is calculated, as others have said, by taking the square root of the deviation in one axis squared + the deviation in the other axis squared and multiplying that answer by 2.

Maybe you need to talk to this kind of engineer:

http://i203.photobucket.com/albums/a...ock/rae2-a.jpg

Not this kind:

http://i203.photobucket.com/albums/a...n_engineer.jpg

[ir a programmer]

Maybe this is the one...?

http://www.sliderulemuseum.com/SR_Im...seEngineer.jpg