Originally Posted by Trickymissfit
first of all when deal with threads that are larger than an inch in diameter the best you can ever hope for is roughly a 60% thread. Some folks do say they can get 65%, but I've never seen anything close to that. (read the Machinest Handbook, or better yet order a copy of thread form statistics from the Bereau of Standards from the Government. This 60% is a Class 1 ground thread. You cannot get the proper helix angle turning a thread in a lathe. A thread that's around 1/2" is best at around 70% to 75%, but the actual contact of the thread form (male to female) will be less. It just a fact of life.
Secondly, should you manage to get that 95% thread contact; all I can say is good luck putting it together. And if by chance you do get it together; then good luck ever getting it apart
do this: Cut a 1.05 thread to match the Savage nut. Now take a magic marker and coat the threads on the male part. Screw it together, and then take it off by screw the nut all the way accross the turned thread. Look at it under a strong light and a magnifying glass. Better yet, if you have access to a shadowgraph. Then cut a section of the nut, and clamp it to the thread form. Results make you wonder how the threads even went together.
not being critical, but I made a living doing this for almost 40 years, and it's just the nature of the beast.
No problem for me to get a better fit than 60%.
If you are referring to nuts and bolts you are pretty close. But we are talking about lathe cut
threads and on firearms that have to deal with tremendous forces and the tenon size has
to be designed to handel this with a 2 to 1 safety factor.
I also made my living dealing with metallurgical connections of all types including bolt strengths
and thread fits and types of threads.
Gun work requires the very best fit possible and if a smith can't do better than 60% then he
is called a plumber (No disrespect to the plumbers but they use taps and dies not a lathe to
If you are happy with 60% thread contact then that is your choice but If I build a firearm it will
have a much better contact area than that or I won't let it out of my shop.
I'm sure there are other smiths on this site that can vouch for 90 to 95% but may not want to
participate in this discussion and some are capable of better threads than that.
The only reason you can't get 100% engagement is that the major and minor diameters
should have a slight radius to prevent galling.
So we are back to the original question To Nut or not to nut. I chose to not use the nut
because it adds one more problem that is not nessary unless you want to switch barrels
often and even Savage will tell you that the barrel nut is for ease of assembly not to switch
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