On Thu, 23 Oct 2008 16:01:10 -0500, Richard J Kinch
wrote:

Ned Simmons writes:

It seems you're confusing allowances and tolerances.

No. Design sizes (what one actually attempts to fabricate) are derived
from the "basic" size (the geometric ideals) with allowance applied.

That's what I said.

The
design limits are then subordinately derived by application of tolerances
to the design sizes.

I don't doubt that's what you meant, but not what you said,
specifically, "To cut real standard threads, you must stay within
allowances..." The allowances are single values, not ranges that "you
must stay within." That's a better description of tolerances.


The common UN threads are a surprisingly complex subject. Consider that MH
takes five pages just to define the terms. Unless you respect them all,
you're just kidding yourself that your results are anything but
accidentally within standard.

Which was my point. It may seem like quibbling, but your use would
likely confuse the concept of allowances vs. tolerances for someone
who hasn't read those pages carefully.

--
Ned Simmons