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Internal/External diameter threading chart

ghostdog662

Aluminum
Joined
May 6, 2010
Location
TX
Does anyone have a chart of the correct diameter a part should be for internal / external threading?

For example if you want half inch threads you should bring the OD to XX size.

I was hoping to blow up a chart and laminate it for my garage.
 
This is the one I've used for years.
ThreadChart.jpg
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Direct link
http://i245.photobucket.com/albums/gg49/calfranch/South%20Bend/ThreadChart.jpg
 
Cleveland Twist Drill

Cleveland makes a poster size wall hanger made of heavy plastic. You should be able to get one free from a Cleveland distributor.
 
Another column I find handy, though it has to be customized a bit, is one telling how far to crank the compound at 29-30 degrees, to get the desired pitch diameter. It's dependent on whether the tool is perfectly formed or has some smaller tip radius but I find that I use the same tool for almost all my small threads, and I keep it sharpened about the same way, so the results are very consistent.
 
Thanks OldMachinist and Gordon B Clarke for these tables, it should take some of the trial end error out of fitting threads for me (I've plotted them both ready to laminate). I have worked out that the external thread needs to be a little smaller than the internal in order for the threads to move past each other but so far have achieved this by trying, resetting and taking another couple of thou off etc. rather than any scientific method.

Gordon - I haven't had a chance to digest the tolerance info given (I design ships and marine structures, not close fitting mechanical parts) - I have seen similar charts before but not been able to work out what they mean. I'll have a look tonight and see if I can get it on my own before I ask you for a dummies guide to tolerances. :)
 
The chart I posted was hand typed many years ago from information in Machinery's Hand Book. The handbook has information on almost any thread you will ever need to make. Machinery's Handbook 28th Edition Toolbox | Industrial Press You can find used copies many places and may want have several copies around. I have 3 copies all different editions. Before I retired I kept one at the house, one out in my shop and one in my toolbox at work.
 
Machinery's Handbook has what you are looking for. Most of my work lately is drawn by me and when it comes to threading, I will note the details on the drawing or a seperate paper. I also have the CD for my puter and will print the info and hang it by the lathe. Handy. I even made my own info sheet for the threads which I do the most to show the compound travel for sharp V and unified. That also hangs by the lathe.
Of course, when doing work for customers, the 'wires' come out to assure the proper size.
 
Gordon, I looked through the charts properly and I think I've got it. I'm not used to tolerance classes and when I first came accross the charts showing the relationships between different tolerances they didn't make any sense - thanks to your sheet they do now!

I know what you mean about trying to get your own name on forums, there is one pretty big forum where I managed to register early enough to bag Jim as a username! I'm actually English but I've been in Scotland for 12 years now, maybe I can become a citizen? :) I started in the shipyards, now in an independent consultancy.
 








 
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