On 25.01.16 14:28, Peter Blodow wrote: > I have run a machine shop with up to twenty workers for 36 years and I > never heard about percentage of engagement etc.
Peter, On the 10.2mm hole for M12x1.75, given in the table you posted yesterday, engagement is 84% - very strong, but hard on taps. Industry standards are necessary, and we rely on bought bolts conforming to them when we tweak % engagement in the tapped hole to receive them. Please have a look at: https://en.wikipedia.org/wiki/Screw_thread under the heading "Thread depth". You will discover that nefarious tapping practices are institutionalised beyond anyone's ability to eradicate. ;-) The text at the OSG calculator, cited upthread: http://www.osgtool.com/Technical.asp?tid=1&id=1 is also relevant. To wit: » To minimize tapping problems and lengthen tool life, use the largest drill possible to produce a minor diameter that will result in the lowest percentage of full thread consistent with adequate strength. A minor diameter that provides a 55% to 65% thread is sufficient for most requirements, but in some cases a higher percentage of thread may be necessary to conform with the minor diameter limits of the thread class specified. « Seriously, once we buy an ISO bolt, we can use it as circumstances permit. In industry, you just need an engineer to sign off on that. Would you like to post the drill size your tables specify for M12x1.5, and we'll check the engagement on that? (The table from yesterday included only M12x1.75, so does not help Tom, or allow comparison with our preferred hole size. ) Erik ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
