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REDesigner09 (Aerospace) (OP)
20 Apr 11 10:38
Hi,

  I'm curious to know if anyone has a turbine blade drawing template with proper GD & T datum schemes on it. Preferably, seeking a template for a jet engine turbine blade with a core, but I'm more interested to see how:

  CAD Datums (from ProE, NX or any CAD application) are used for
GD & T datums.

  For example, when creating CAD models, CAD datum features are often used to symbolize the centers of a (symmetrical) part. However, I'm aware that GD & T requires datums to on surfaces. I'm curious to know how other (turbine) industries use or deciphers these CAD datums vs. GD & T Datums.

Thanks
dgallup (Automotive)
20 Apr 11 12:03
I would expect that to be highly proprietary.
ctopher (Mechanical)
20 Apr 11 13:57
I agree with dgallup.
I have done fan blades in the past, they were highly proprietary...especially for jet engines.
You must have previous drawings at your company to use as reference?

Chris
SolidWorks 10 SP4.0
ctopher's home
SolidWorks Legion

Belanger (Automotive)
20 Apr 11 15:43
Agree with the above... but I am guessing that such a geometry would require datum targets.  Perhaps investigate that route; talk to the folks measuring the blades and see what would make good CMM points to establish the datum center line.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

REDesigner09 (Aerospace) (OP)
20 Apr 11 15:46
Hi,

  I'm not asking for your actual part drawing.  I just want to reconfirm some basic datum usage between CAD Datums & GD & T datums & how they are deciphered or referenced between the CAD Model(s) & Drawing(s).


  I don't need to see title blocks  or company names.  A screen shot of a partial view will do, highlighting the Primary, Secondary & Tertiary GD & T Datums compared with CAD models Primary, Secondary & Tertiary CAD Datums.

Thanks

 
lifttrucks (Mechanical)
20 Apr 11 16:41
Hi REDesigner,

What do you mean by CAD datum? The plane/axis you are mating a part to?
KENAT (Mechanical)
20 Apr 11 16:52
I'm guessing he means the CAD model 0,0,0 coordinates and/or default datum planes or similar.

This practice would seem questionable.  I think looking at datum targets like Belanger says might be worth while.

Posting guidelines FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm? (probably not aimed specifically at you)
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?

REDesigner09 (Aerospace) (OP)
20 Apr 11 17:59
Lifttrucks,

  Yes, CAD Datums used within ProE, NX or whatever other CAD system that are typically used as Primary, Secondary or Tertiary datums when creating (symmetrical) CAD models.

 I'm guessing the terminology is getting confusing because "Datums" within CAD modeling practices is different than "Datums" within GD & T standards.

  What I'm trying to figure out is why some major turbine companies, both in gas & aerospace use "CAD Datums" as their "GD & T Datums" also.

  This does not appear to be an acceptable practice within the ASME standards & yet, it's been used for years & far as I know, is still being used.

  Trying to figure out if there's an exception to this standard or another explanation that I'm not aware of.

Thanks
 

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