07-13-2013, 10:06 PM
Ed,
5/16" is the minor diameter of a 3/8-16 internal thread (tap drill size). The minor diameter of a 3/8-16 external thread must be slightly smaller for clearance, hence the .2983 dimension.
Marfaguy, your gear selection and settings sound correct for a 16 pitch thread, but you should always take a scratch cut and verify the pitch before cutting the thread. You may also want to invest in a copy of the Machinery's Handbook (any edition). That is the machinists bible and will include pretty much any information you'll ever need.
Tom
5/16" is the minor diameter of a 3/8-16 internal thread (tap drill size). The minor diameter of a 3/8-16 external thread must be slightly smaller for clearance, hence the .2983 dimension.
Marfaguy, your gear selection and settings sound correct for a 16 pitch thread, but you should always take a scratch cut and verify the pitch before cutting the thread. You may also want to invest in a copy of the Machinery's Handbook (any edition). That is the machinists bible and will include pretty much any information you'll ever need.
Tom
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