Controling a very simple "localisation"

[guillaume_martin]

Hello !

First of all, how do we name in english the french word "localisation" ? (You can see it in the attached document)

So, excuse me, but I will say "localisation" in this question !

So, to control the very simple "localisation" in the exemple, I would do so :
- Measure the plane "A".
- Construct a plane, parallel to to plane "A", but translated of 45 mm.
- Measure points of the "toleranced ?" plane.
- Verify that the points of the "toleranced" plane are not at more than 0,1mm of the translated plane.

Is it correct ?
Is there a more simple method ?

Thank you very much for your attention,
Excuse me for "localisation" and "toleranced" !,

Guillaume

[Wes Cisco]

The symbol on your sketch, we call "True Position". You can use it, but "Flatness" and or "Profile" generally work better with planes than truepostion. I would do it this way.

1) Measure Datum A
2) Alignment > Level to Datum A
3) Measure the plane to be toleranced
4) Make sure I am in the correct work plane
5) Dimension plane for True Position in one axis only, the one the 45mm applies to.

HTH

[John Kingston]

What Wes said is correct. This could also be called location if it used standard tolerancing. True Position is the Geometric Dimensioning and Tolerancing method.

[cmmguy]

I saw you other post about constructing a plane. Both Wes and John pointed out that it is not necessary to construct a plane to measure it or tolerance the measured plane. Hopefully I am not missing why you constructed the plane in the first place.

[guillaume_martin]

OK ! Thank you !

Wes : Why have I to be sure that I am in the correct work plane ? If I did an aligment, (for exemple), Z is perpendicular to the plane, so, if I measure the true Position in axis Z, it should be correct ? No ?
In fact, I think I did'nt understood the concept of workplane !!!

cmmguy : I wanted to construct this plane, because I'm 28 years old but already have grandpa practices ! In an old cmm software (programmed by french teacher bhouhh !), we needed to construct this plane, for reasons of the last century !

Thanks a lot !

Guillaume

PS : Now, I can read the 11 pages founded with the keyword "True Position", and the 17 ones with "lication" !

[Wes Cisco]

Guiluame,
The software "sees" your part in two dimensions. Some objects are always 3 dimensional and work plane independant, but many are not. It is good practice to always be in the proper work plane for the software to "see" what you want to do. The example I like to use is take a coin and lay it on the table of the CMM. When you stand over it and look down, that is the Z+ work plane and you "see" a circle. If you squat in front of or beside the table and look at the edge of the coin you "see" a line. These are the Y and X workplanes. With planes, since they are 3 dimensional objects, trueposition of the Z axis while in the Z workplane might work just fine, or it might not. Pc-Dmis is quirky about this. I do know if you tried to get a 2D dimesion you would have to be in either X or Y workplane, not Z. HTH

[guillaume_martin]

Thank you Cisco !

With this answer, I have to reconsider my way of using PCDMIS !

For somebody "theorical" like a teacher, I seems to be curious ! : it could be so easy to work in 3D ! But I'm sure it has very practicals reasons in the "concrete wold" !!

Thank you again !

Guillaume

[Paul Sarrach]

There are to many ways for me to give one solid argument.

I would ask for a clarifaction on this one.

But as another option you could take points at 45.0 and tolerance the T Value at +/- .1 Or a

Or Take the Distance from the Plane and points @ 45.0 +/- .1