Sorry, the mail didn't transport the table like it was supposed to. I try again without table function:
Thread Pitch Core diam. bolt Core diam. nut Drill size mm Wrench size mm M1 0,25 0,693 0,729 0,75 - M1,2 0,25 0,893 0,929 0,73 - M1,6 0,35 1,171 1,221 1,30 3,2 M2 0,40 1,509 1,567 1,60 4 M2,5 0,45 1,948 2,013 2,10 5 M3 0,50 2,387 2,459 2,50 5,5 M4 0,70 3,141 3,242 3,30 7 M5 0,80 4,019 4,134 4,20 8 M6 1,00 4,773 4,917 5,00 10 M8 1,25 6,466 6,647 6,80 13 / 14 M10 1,50 8,160 8,376 8,50 17 / 16 M12 1,75 9,853 10,106 10,20 19 / 18 M16 2,00 13,546 13,835 14,00 24 M20 2,50 16,933 17,294 17,50 30 Now, I hope that's better. Many of the drill size values were even smaller (tighter) before the DIN was changed some years ago: e.g. M2.3 and M2.6 were united to M2.5, M3.5 was (almost) cancelled though it still is a very common thread with electric appliances, etc. Peter. Am 24.01.2016 13:28, schrieb Peter Blodow: > Erik, I don't know wat table you were glancing at, but here is the table > from Europes No:1 tool seller, Hoffmann Group > (http://www.gewinde-norm.de/metrisches-iso-gewinde-din-13.htm), listing > metric ISO / DIN13 threads: > > Thread Pitch Core diam. bolt Core diam. nut > Drill size mm Wrench size mm > Gewinde > Steigung > > Kerndurchmesser > Bolzen > > Kerndurchmesser > Mutter > > Kernlochbohrer > > Schlüsselweite > (Sechskant) > M1 > 0,25 > > 0,693 > > 0,729 > > 0,75 > > - > M1,2 > 0,25 > > 0,893 > > 0,929 > > 0,73 > > - > M1,6 > 0,35 > > 1,171 > > 1,221 > > 1,30 > > > 3,2 > > M2 > 0,40 > > 1,509 > > 1,567 > > 1,60 > > 4 > M2,5 > 0,45 > > 1,948 > > 2,013 > > 2,10 > > 5 > M3 > 0,50 > > 2,387 > > 2,459 > > 2,50 > > 5,5 > M4 > 0,70 > > 3,141 > > 3,242 > > 3,30 > > 7 > M5 > 0,80 > > 4,019 > > 4,134 > > 4,20 > > 8 > M6 > 1,00 > > 4,773 > > 4,917 > > 5,00 > > 10 > M8 > 1,25 > > 6,466 > > 6,647 > > 6,80 > > 13 / 14 > M10 > 1,50 > > 8,160 > > 8,376 > > 8,50 > > 17 / 16 > M12 > 1,75 > > 9,853 > > 10,106 > > 10,20 > > 19 / 18 > M16 > 2,00 > > 13,546 > > 13,835 > > 14,00 > > 24 > M20 > 2,50 > > 16,933 > > 17,294 > > 17,50 > > 30 > > > Greetings > Peter > > Am 24.01.2016 10:18, schrieb Erik Christiansen: >> On 23.01.16 12:27, Gene Heskett wrote: >>> Now we are getting more precise than we can drill with the typical drill >>> bit, which usually drills oversize because the tip flats are >>> un-avoidably off center. Even to a small extent for pricy carbide bits >>> in the smaller sizes. Yesterdays finished tapping looked great, but I >>> think I could have used the next larger #drill. Yeah, my back of a >>> napkin said a .089 drill, kcalc says 0.0984251968503937008 for a 3mm.5 >>> screw. >>> >>> No wonder I felt like I should peck it, the hole WAS too small. >> Ahem, it was WAAAY too small. ;-) >> >> Just a glance at the table upthread shows that 2.6mm (0.102") gives 65% >> engagement, which is as much as I ever want on M3, to avoid busting the >> tap. Even kcalc's 2.5mm (0.098") drill is too small, giving a dangerous >> (to small taps) 82% engagement. >> >> And that .089 (2.26mm) gives an engagement of: >> >> E = (OD - Drill_Size)/2kp >> = (3 - 2.26)/(2*0.613*.5) >> = 120% >> >> That has the tap drilling as well as tapping! >> You did superbly to not break the tap, Gene. >> >> I tried a 2.5mm (0.098") drill for M3. Once. >> Although the tap didn't break, I went straight out and bought a couple >> of 2.6mm drills. Now I can tap M3 without my hair standing on end. >> >> 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 >> > > > --- > Diese E-Mail wurde von Avast Antivirus-Software auf Viren geprüft. > http://www.avast.com > ------------------------------------------------------------------------------ > 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. 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