"Rich Grise" wrote in message
...
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


Roughly speaking, the o-ring will increase in width by the inverse of the
fraction it is compressed. In other words if it is compressed by a factor
of 0.8, the width will expand by a factor of 1.25 .

In your case the maximum diameter is .281 and the minimum compressed height
is .226, So the maximum width is .281(.281/.226) = .349 so a groove of
..375 makes sense.