Metric thread form tap, drill chart

[conceptmachinin]

Hello there and thanks in advance for the help.

I'm looking for a link or a file for metric thread form tap drill chart. Can someone please help me out?


Thanks

Jimmy

[Ken_Shea]

Jimmy,
Not a Freebe but invaluable IMO.

http://mrainey.freeservers.com/MEPro.html

http://mrainey.freeservers.com/METhreadPal.html

Ken

[star-turn]

Try this:

lists most threads and you can open up an excel file with all the data supplied ( as per Zeus book)

http://www.colinusher.info/Livesteam/mewdata.html


ST

[ctate2000]

Metric tap drill is easy. Subtract pitch from nominal diameter the result is your tap drill daimeter. M8x1.25 would require a 6.75 diameter drill.

[HIRAH]

Metric tap drill is easy. Subtract pitch from nominal diameter the result is your tap drill daimeter. M8x1.25 would require a 6.75 diameter drill.

actually, this won't work for thread forming. regular tapping yes, but thread forming has a bigger minor diameter and a tighter tolerance for the hole size.

here is how to figure out thread form drill sizes

m6x1=.23622 diameter
65% thread
threads per inch 25.4
drill size = .23622-((.0068x65) / 25.4)

=.23622-(.442/25.4)
=.23622-.0174
=.2188

there is only about +/-.0015 from here for 55% or 75% of thread.

now you don't need a stupid chart