I've added this information on the 75 grain steel BH adaptor thread, but figure some won't check there. It's beginning to appear that there is a vast construction difference between some of the 75 grain Bh adaptors on the market. The ones I got from 3 Rivers have proved very fragile, and prone to failure.
Here are the measurements from those I have, which are snapping apart with alarming frequency. See the '75 grain steel adaptors' thread for full details.
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MEASUREMENTS
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Ok, borrowed some vernier calipers from Harrold. He's a retired machinist/metal worker, so pretty good at precise measuring. Here are the dimensions we're measuring on the 3 Rivers 75 grain adaptors I have.
(1) 'Straight line' length of the taper (outside): 0.650"
(2) Depth of the counter-bored hole at the center (Check photo of broken shank, on page 1. The counter-bore has a conical termination): 0.671" (Note that the center of the counter-bored hole extends 0.021" beyond the taper - actually extending that far up into the metal of the shank.)
(3) Depth of the counter-bored hole at its edge: 0.640"
This means the calculated thickness of the metal holding the shank to to tapered portion of the adaptor is 0.010". That's ten one-thousands of an inch.
The "break-ring" showing on the shank(s) is so thin that neither Harold nor I could accurately measuring it with the vernier calipers; to verify the calculated thickness of attachment. However, we both did a visual comparison of the break-ring's width to some feeler guages, and both came up with 0.010". Appears to be an accurate measurement of the thickness of steel holding the adaptor's shank to its tapered portion. That is far, far too thin, by anyone's standards.
Ed
TGMM Family of the Bow
Topic: Need Assistance - Measurements on the Snapping Steel Adaptors (Read 287 times)
