<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div style="-webkit-text-size-adjust: auto;">The Bolt Science website has some great info - perhaps there's something in here that will answer this?</div><div style="-webkit-text-size-adjust: auto;"><br></div><div><span style="-webkit-text-size-adjust: auto;"><a href="http://www.boltscience.com/pages/info.htm?">http://www.boltscience.com/pages/info.htm?</a></span></div><div><span style="-webkit-text-size-adjust: auto;"><br></span></div><div><span style="-webkit-text-size-adjust: auto;">The Short Bolting article says: "</span><span style="font-style: italic; background-color: rgba(255, 255, 255, 0);">It is common practice to specify that two thread pitches must protrude.".</span></div><div style="-webkit-text-size-adjust: auto;">I guess that implies spec over standard.... There may be other info in a different article.</div><div style="-webkit-text-size-adjust: auto;"><br></div><div style="-webkit-text-size-adjust: auto;">A bit off-topic, the poster under the heading "Why nuts and bolts come loose" would be a great addition to any shop wall, and the contraindication of using "helical spring washers" (split lock washers) was news to me, but makes total sense.</div><div style="-webkit-text-size-adjust: auto;"><br></div><div style="-webkit-text-size-adjust: auto;">HTH,</div><div style="-webkit-text-size-adjust: auto;">Jen</div></body></html>