On Thu, 23 Oct 2008 10:00:47 -0700, Jim Stewart
wrote:


Another question, if I'm making a set of drawings for
a machine shop to fabricate, do I have to draw the
whole form with all the dimensions or can I just spec
7/8-20 UNEF 2B on the drawing?

That's the complete and proper callout for a standard UN thread,
there's no need to graphically dimension the thread. You can specify
thread depth either in the callout or by dimensioning the appropriate
drawing view. Barring any ambiguity, I prefer putting it all in the
callout.

Here's what my templates for thru and blind holes look like. (DP)
stands in for the ANSI depth symbol, the one that looks like a down
arrow with a cap.

7/8-20 UNEF-2B THRU

7/8-20 UNEF-2B (DP) 1.25 MIN
TAP DRILL (DP) 2.00 MAX

--
Ned Simmons