On Tue, 18 Jan 2011 12:30:02 -0800, Rich Grise
wrote:

The machinist called me over and asked me to help him design an o-ring
groove. We looked up a chart at
http://www.parker.com/literature/ORD...g_Handbook.pdf

and on page 89 of the above PDF, there's a chart: Design guide 4-2.

It's clear that for nominal 1/4" (actual width .275 ± .006) the gland depth
(dim. L) is .226-.229.

But on the chart, it seems to indicate that the groove width, G, for a
nominal 1/4 width, is .375-.380, which he thinks (and I tend to agree, but
I'm not the machinist - I just draw the pretty pictures) is too wide and
the o-ring would flop around or something. He thinks the groove width
should come from the line above, and be .281-.286.

Anyone got the definitive answer for that?

Thanks 10E9 in advance!
Rich

You're not working at TCFNA Morton-Thiokol are you?

I think the number is about right. The O-ring squishes out sideways,
and you have to consider the tolerances of all dimensions and the
O-ring itself. A maximum size O-ring has to fit a minimum size groove
and gap.

Not much bad will happen if the groove is a bit wider than required
for the particular O-ring, but bad things will happen if the depth is
out of tolerance or the groove is too narrow.

Here's another source with exactly the same numbers for radial squeeze
applications (see page 9). Smaller numbers for axial and smaller again
for vacuum axial.

http://o-ring.info/en/technical%20ma...nformation.pdf