Problem- Metric thread depth

[surfit]

I am reverse engineering a draw tube adapter for my collet chuck that has an internal metric thread that has a Ø58mm minor dia with a 2.0mm pitch. I looked in the machinist handbook and did not see anything that fits those domensions. I figure that if I knew the thd depth for the pitch I could use that to get me close. I googled "metric thread depth" and found a site that showed a metric thread depth spec 0.614 x pitch. On the same site they show a table with Thread size, pitch, tap drill size. I found a Ø58mm drill size with a 2.0 pitch and a thread size Ø60mm. That would be a depth of 1.0mm but if you multiply .614 x 2.0 it equals 1.228. What am I missing? I would use the draw bar for a gage but that is attached to the 3 jaw chuck that I am using to machine the part. Any ideas?

[Bent]

When you make a metric thread the depth is always the same as the pitch. Depth is on the dia.

Regards Bent

[surfit]

Thank's that makes it quite simple and easy to remember.

[juergenwt]

You are looking at the tap drill size - as Bent said : Nominal size minus pitch. This goes for metric threads
and 60 deg. inch threads also.
the full theoretical depth "H" is given as 0.866xP. This is from a (theoretical) sharp point on top and bottom of the 60 deg. .
0.614xP (h3) is from the radius (R=0.144P) at the bottom of the EXTERNAL thread to the top (nominal size).
More info here: http://www.engineersedge.com/hardwar...ead-sizes1.htm
and here: http://www.gewinde-normen.de/en/iso-coarse-thread.html

[mactec54]

Hi surfit

The correct depth for a 2mm pitch is 1.2269mm or .04830 this is for internal, They are not the same as the pitch