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Tolerance on Sketch Dimensions

Pioneer
Pioneer

Hi

 

Some System (eg ProE) have a possibilitie to define Tolerance on Sketch Diemensions.

We in NX can also do this. But then ProE changes the Distance of the geometry to the middle of the Tolerance.

Meaning: Distance 50 +0.1/+0.2 the meassuered Distand of the Sketch would then be 50.15.

Is there any Way to have someting like this in NX ??

This would be a greate feature and option i think so if not possible yet.

 

Roland

13 REPLIES

Re: Tolerance on Sketch Dimensions

Solution Partner Legend Solution Partner Legend
Solution Partner Legend

Hi oases,

 

Actually we can also define tolerance in that format in NX.

Just right click the dimension and choose edit. See the picture below for reference.

tolerance.JPG

Re: Tolerance on Sketch Dimensions

Pioneer
Pioneer

Hi

 

Thank you. Yes i know but the Size of the sketch does not change.

In NX if you set (example) Dimension 50 +1/+2 the size of the Sketch still stays at 50mm but realy should be 51.5 to be in the middle of the Tolerance.

Tolerance on Sketsches Yes, but geometry change to middle tolerance ????

Roland

Re: Tolerance on Sketch Dimensions

Pioneer
Pioneer

Hi

I tried this but whatever i do the 54.0 stays 54.0.. how did you this exactly in NX10

Roland

Re: Tolerance on Sketch Dimensions

Pioneer
Pioneer

Hi

What you did was in Drafting adding a Tolerance to a dimension where your Distance did not change to middle tolerance.

 

I talk about in sketching adding Tolernance and the system changes the geometry to middle tolerance.

 

Roland

Re: Tolerance on Sketch Dimensions

Siemens Phenom Siemens Phenom
Siemens Phenom
Hi Roland,
This is indeed a long debatable question...if we need to have a mid tolerance model or simply the model with nominal dimensions and tolerances defined. Since every industry has it own manufacturing standards and capabilites so it would be nice to know the exact reason why there is need of mid tolerancing model.May be the milling operator will see benefit from the mid tolerance model but do we need to have a seperate drawings for inspection or other applications. To me the model with nominal dimensions and tolerances specified should depict the correct design intent.
Would certainly like to hear it out from industry experts.
Thanks and Best Regards
Kapil Sharma

Re: Tolerance on Sketch Dimensions

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

Being a CAM person, I would like to see the model size be the middle of the tolerance band.  So something dimensioned as "2.0 +0.0 -0.01" would actually be 1.995.  Saves lots of issues when NC programming.

I actually asked about this a long time ago (I think on this forum or the older BBS forum).

 

Of course, I don't know why they can't just design it to 1.995 and put a +/- .005 tolerance, and dimension as such on the drawing, but old habits die hard, and apparently doing it that way "would be the end of the world as we know it" ;-)

 

Ken

 

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled


Re: Tolerance on Sketch Dimensions

Siemens Phenom Siemens Phenom
Siemens Phenom

I always understood that with tolerances like that that the number was what your would ideally like the final result to be or what we called the nominal value, and that the tolerances represented what you were willing to accept in terms of deviation from the ideal or nominal value.  Therefore, in your example of "2.0 +0.0 -0.01" the value that I want is 2.0 but I'm willing to accept any value  down to 1.99.  Therefore, I want manufacturing to shoot for 2.0 if possible, not some other value.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA

Re: Tolerance on Sketch Dimensions

Gears Esteemed Contributor Gears Esteemed Contributor
Gears Esteemed Contributor

John -

I thought you retired :-)

 

Yes, BUT

As an NC programmer, I'm gonna make it 1.995 +/- .005

Even if my machine & tool and cut strategy can hold +/- .002, I'm (probably) *still* gonna make it 1.995, unless someone forces me to do otherwise.

 

So now I have to modify the model to change the size by .005

OR

Remember in EVERY operation that deals with that feature, to put -.005 stock on that feature.

 

What a PITA!

Ken Akerboom Sr CAx Systems Engr, Moog, Inc.
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled


Re: Tolerance on Sketch Dimensions

Siemens Phenom Siemens Phenom
Siemens Phenom

I may be retired, but I'm not dead Smiley Very Happy

 

But technically that would NOT be attempting to achieve the design intent.  Otherwise we would all be working under a rule that only allowed plus/minus tolerances of the same value.

John R. Baker, P.E. (ret)
EX-Product 'Evangelist'
Irvine, CA