Slot TP revisited

[JamesMannes]

Hello, My name is Johnny Cash,

I've got another question regarding the slot TP from my previous thread...http://www.pcdmisforum.com/showthread.php?t=925
Seeing as there isn't a diameter call-out associated with my FCF, why does PC-DMIS give me a daimetrical tolerance zone using only the one axis? For example, using only the x axis MMC and the LF, My x axis deviation was .294. The TP showed exactly double that number. that does not seem correct? I should only see the .294 deviation no?
Help me to understand.

[david phillips]

True position 1 axis is double @ deviation from nominal.
0.5 true position = ± 0.25

[JamesMannes]

Can you give me a rationale for that hypothesis?

[Matthew D. Hoedeman]

TP is a DIAMETER value, a single axis deviation is a RADIUS value. Thus, to get TP the RADIUS value is doubled to get the DIAMETER value.

[Paul Barriage]

Just wait till they mistake the angle deviation as the true position.....

[Scott Gooch]

True Position Tolerance Zones

My employer held a GD&T seminar last year, and a GD&T specialist conducted the class. One of the things that he pressed on us was the face that ALL GD&T tolerance zones are TOTAL. Therefore, you need not be confused about the shape of any zone. ALL zones for True Position, Runout, etc., are round zones. One thing that helps is to imagine what a hard gage would look like.

When you have a single axis True Position, do not be confused, the tolerance zone is still round, and has a size that matches the number in the control frame, along with applicable bonus.

Hope this helps.

Scott

If we don't hang together, we shall most assuredly all hang separately.

[layout tech]

James

The reason TP is double when you pull TP in 1 axis is:

Formula for calculating TP Is Deviation Squared plus Deviation Squared
Square Root of total multiplied 2 = TP

(0 Squared + .25 Squared take Square root = .25 x 2 =.5

Hope that helps explain

[John Kingston]

James

The reason TP is double when you pull TP in 1 axis is:

Formula for calculating TP Is Deviation Squared plus Deviation Squared
Square Root of total multiplied 2 = TP

(0 Squared + .25 Squared take Square root = .25 x 2 =.5

Hope that helps explain

Well put. I tried to figure out how to type this in, but couldn't get it to make sense. I'm stubborn and like the symbols.

[JamesMannes]

Thanks a ton for the info guys. It is much appreciated. That was my problem I was looking at this another way. Thanks again.

[TRD_racing]

James,

I scanned a couple of pages out of my GD&T book that might possible help you. I zipped it up but it is still to large to get on this page. If you sent me a private message w/ your email I will sent it to you.

[gage guru]

yea I guess it would be nice to have a little more room to get larger documents into this forum for help....it really is a killer at times....