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Your first post says you're wanting to turn for a 3/8-16 thread, not a 5/16" thread. For a 3/8-16 thread the minor diameter is 5/16" (.3125). What thread are you wanting to turn? A 3/8" or 5/16"?
Ed
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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
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Ah, OK, got it Tom. Thanks for clearing that up.
Ed
(07-13-2013, 10:06 PM)TomG Wrote: 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
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(07-13-2013, 10:06 PM)TomG Wrote: ...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...
Plenty of these on eBay and you are looking for the actual "Machinery's Handbook", not the "Machinery's Handbook Guide".
HERE is one that ends today, has no (visible) bidders and the starting bid is $20.00.
If you are patient you can get them cheaper and don't be afraid to buy one that is 50 or 60 years old, Such as
THIS ONE
Hunting American dentists since 2015.
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Thanks guys. Sorry for the confusion Ed.
If it's crazy but it works, it's not crazy.
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Location: Maryland USA
Marf.
Single point threading is extremely easy and nothing to worry about. I would take the suggestion earlier mentioned regarding practicing on some PVC pipe it works like a charm.
one of the best tutorials on the web for single point threading has beed done by Tubial Cane Here is the link
http://www.youtube.com/watch?v=9y0MmvscBzg
A little advice, your going to get a little flustered achieving the minor diameter at first, its very hard to measure if you have not done it before, the offset compound will get you there if everything works well, dont forget if you get close you could always finish it off with a die there is no shame in that.
Enjoy your threading,, let us know how you get on.
ieezitin, proud to be a member of MetalworkingFun Forum since Jan 2013.
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As everyone has mentioned.......PRACTICE!
Your hand to eye coordination must be pretty good too......especially threading up to a shoulder!
The Machinery Handbook "can" be a useful item to have around, however......I have one sitting on desk that I seriously doubt I have opened in ten years. FAR from knowing it all.......it's just MUCH easier and MUCH quicker to get a response in simple laymans terms on the internet, and often times several different approaches with tips and tricks for achieving what you need to know or do.
When you do find what you're looking for on the net, (which often times is a page of charts or formulas for what you need) simply bookmark it and it will always be there just a simple click away from providing you the info you need.
Here's an example of some I use that you may find of interest:
Form Tap Chart:
http://www.championscrew.com/form_tap_drill.htm
Thread Chart:
http://www.shender4.com/thread_chart.htm
Trig Calculator for right angles:
http://www.carbidedepot.com/formulas-trigright.asp
Milling Formulas:
http://www.carbidedepot.com/formulas-milling.htm
More Charts than you can shake a stick at! :
http://www.carbidedepot.com/resources.htm
Best Regards,
Russ