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Geometric tolerances: concentricity

EddyVE

New member
Hi all,



I'm having some difficulties creating a 'concentricity' geometric tolerance (WildFire 1.0).



Suppose a shaft with a reduced diameter at one end. I want to specify
that the reduced diameter must be concentric to the main diameter of
the shaft.

In WF, I can not directly connect both diameters with the concentricity
GTOL symbol as I used to do on the manual drawing board, so I have to
set a reference datum.

But how to set a cilinder surface as a GTOL reference datum?? I can only set a flat datum plane as reference datum.



I managed to get a GTOL reference symbol attached to the shafts axis,
but I can not reference that in the concentricity GTOL symbol, nor can
I 'Show/Erase' the axis reference symbol.. It seems to lead a life of
its own...



Can anybody give me some advice or point me to a tutorial or something?



Kind regards

Eddy





Edited by: EddyVE
 

dr_gallup

Moderator
You must use an axis for the Gtol datum. When you set the axis as a Gtol datum you have the option to apply the datum to a dimension. Pick the main shaft diameter dimension. Now the datum symbol only shows on the dimension, not the axis. You will be able to use the set datum axis in creating your concentricity Gtol.
 

EddyVE

New member
Dr_Gallup,


I finally managed to get what I want. It was a little more complicated than the simple example I mentioned because my model in fact is a welded assembly, composed of 3 rings. This made things a bit harder, but I succeeded thanks to your help.


Thanks a lot!!


Kind regards


Eddy
 

BonesNTX

New member
Most all occurances as you describe are more correctly called-out as "runout". Your concentricity most likely will be machined (?) and most certainly measured via runout measurements. Concentricity checking requires more work from the inspector to establish the centerline of each feature and is typically not of any advantage.
 

EddyVE

New member
Bones,

You are correct. Specifying geometric tolerances and checking them are 2 different things.
Using geometric tolerances is basically a way to let the man, who produces the part, know what YOU, as the designer, think is important about the part regarding its functionality.
Rarely ever have I had the need to ask for a measuring report.
The fact alone that there are GTOLs used on the drawing will make the operator pay more attention to the part. Unfortunately sometimes it also increases the manufacturing price...



Kind regards
Eddy
 

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