Bolt Diameters

There was an earlier thread

http://cr4.globalspec.com/thread/10003/Calculating-the-root-area-of-a-bolt

Though I personally don't understand what has bolt root area got do do with TEMA? It is supposed to be as per the bolt standards. And that is available in any handbook, based on major diameter, tolerance class and pitch.

hi

In metric stds M90 bolt should have OD 90mm.

Depth of cut of threads =( OD - Root Dia)/2

I hope from the above Eq you will get a clearcut idea regarding root dia.

Depth of Cut = (OD - Core Dia)/2

An example of the above equation is:

M5 x 0.80 ISO metric coarse thread - (5mm - 4.0184mm)/2 = 0.4908mm

M8 x 1.25 ISO metric coarse thread - (8mm - 6.4664mm)/2 = 0.7668mm

M10 x 1.50 ISO metric coarse thread - (10mm - 8.1596mm)/2 = 0.9202mm

To find the Core Dia transpose the formula (the hard way) or look up on a data sheet or reference table.

I don't know what TEMA is but 'Guest' is right....bolts have their own standards to conform to.

There is a BS (Can't remember the number, haven't used it for some years now) which lists data for nearly every size bolt and pitch up to about 240mm dia in 5mm increments over 100mm dia and for much smaller increments below that. To work it out for M65.3 just look at a standard thread size of the same pitch and do a simple subtraction to obtain the data you require.

Be careful, there are some errors which BS are aware of but haven't put right yet.