Well there are standards but more and more it doesn't look like they are being followed.
Since this forum is all about CNC my request follows with the subject of power tapping. To hold the taps so they don't spin in the collets I found what are called Tap Collets in the ER20 size. The attached chart shows the sizes and the photo is of the JIS variety. The collets are slit 4 ways on each end rather than 8 so they are not nearly as flexible. Where an ER20 collet might be rated as 5mm-6mm or 6mm-7mm the tap collet is marked [M6 6.3-5] or [M8 6.3-5] If you have an ISO 6.0x1.0mm tap the shaft part will be 6.3mm and the square, which fits in the square part of the collet to prevent the tap from spinning, will be 5mm square. When my 6mm tap didn't fit in the M6 collet I complained to the supplier and got the same shrugged shoulders. However both my M4 and M5 taps fit into the M5 collet which is also wrong. So I thought I'd buy American and order an M5 and M6 for $20 each. The taps arrived with several part numbers and Made in USA laser engraved on them. The shaft measured 6.42mm and wouldn't go in. The Chinese 8mm tap with the 6.3 shaft went smoothly into the collet marked M8 (or M6). And it measured exactly 6.3mm. To get the tap in I resorted to force. I jammed 3 thin bladed flat screwdrivers into three of the slots on the collet. The US M6 tap now dropped into the now larger than 6.4mm hole and an 1/8 turn twist of the tap made it drop further into the square hole. Pull the screwdrivers and the tap was held tight. Tighten the collet and the TTS ER20 appears to turn the tap true. All this is of no importance, as demonstrated by the huge forum response of actual tap measurements, unless you have specific holders for tools that are supposed to be of a specific dimension. Then it is important. And I'm sure there are those who hold it in a drill chuck and have no problem with it spinning in the chuck. Or in a standard collet without issues. I don't seem to have that luck. Anyway. My request for measurements was to try and get an idea of how widespread tap shank and square variations are. John > -----Original Message----- > From: Roland Jollivet [mailto:roland.jolli...@gmail.com] > Sent: December-09-21 9:22 PM > To: Enhanced Machine Controller (EMC) > Subject: [Emc-users] Tap size > > There is no standard, but mine are �6 and 5.85mm > > To illustrate, here are two M4 taps from the same supplier, YG. Obviously > SF and SP, but the main difference is that the one on the left was bought > about 5 years ago. > What you see is shrinking, just like your packet of biscuits is getting > smaller... > > I got mad at the vendor, because the new style has less reach and is more > difficult to handle. He just shrugged his shoulders.. > > Roland > > > > > On Thu, 9 Dec 2021 at 23:01, johnd <jo...@autoartisans.com> wrote: > > > Mini surveyIf you have an M6 x1.0 tap in your tool box what is the shank > > and flat dimension?Sent from my Samsung S10 > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > >
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