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Re: Draft


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Posted By<" ">peterN on April 10, 2002 at 19:06:22:

In Reply to: Draft posted byDonald on April 10, 2002 at 15:32:26:

Don,
Here is my opinion of your situation. FYI, I am a mechanical designer with over 20 years experience, and have designed and detailed my fair share of molded parts. Wish I could see the print. Brace yourself..........

Issues regarding draft are not addressed in Y14.5M-1982.

In my opinion, if ANSI Y14.5 is applied 'by the book', then the feature can not exceed the upper and lower limits of the feature size dimension on the drawing anywhere along it's entire length regardless of whether it has positive or negative draft. Draft direction (plus or minus) does not appear to be clearly stated nor is draft defined in the part view as 'per side' or 'included angle'. Therefore, as previously stated (in my opinion) the feature can not exceed the upper and lower limits of the feature size dimension on the drawing anywhere ALONG IT'S ENTIRE LENGTH. Harsh, I know, but the 'omissions' with regard to feature draft direction and per side/included angle unfortunately constrain the part to feature size tolerance limit only. OUCH!

(for anyone reading this, I highly recommend drafted features to be stated as follows on drawings so as not to be open interpretation.)

Feature = .xxx diameter

Always specify
1. Feature size
2. Tolerance (if different than title block default)
3. Draft PER SIDE
4. Direction of draft

Therefore an unambigiuos dimension for this feature becomes (all stated as ONE DIMENSION):

.XXX +.XXX/-.XYZ PLUS (or minus) X DRAFT PER SIDE.

Peter N




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