Standard for how many threads to be out from a nut
Standard for how many threads to be out from a nut
(OP)
Good morning everybody
I run in to a problem that some of the customers request to have a minim of 3 threads to be out of every fastener set.
I know that there is a standard for this situation but I can't find it. I would like to know what the reason is and actually what is the formula to calculate how many threads to have out.
Can somebody guide me in this matter?
Thank you!
C
I run in to a problem that some of the customers request to have a minim of 3 threads to be out of every fastener set.
I know that there is a standard for this situation but I can't find it. I would like to know what the reason is and actually what is the formula to calculate how many threads to have out.
Can somebody guide me in this matter?
Thank you!
C





RE: Standard for how many threads to be out from a nut
Never seem a standard for it but normaly I would have 3 to 4 threads coming out of the nut, the reason is to ensure you have full thread engagement of the nut.
Again no standard formula just add up your joint dimensions + nut thickness and add on appropriate length to
fastener.
regards
desertfox
RE: Standard for how many threads to be out from a nut
I was thinking the same way, but I was told to look for a standard...
RE: Standard for how many threads to be out from a nut
Be careful of having too many threads out the bottom. The standard I use is usually 2 threads when doing a visual check or calculating grip length. The reasons for doing so are to ensure full nut engagement while minimizing weight and ensuring the bolt shank does not run into the nut.
The last one is critical for machine-type bolts that have a smooth shank. If the shank should run into the nut, then poor clamp-up and possible bolt and/or nut damage may occur. This condition presents significant fatigue issues for the fastener system.
jetmaker
RE: Standard for how many threads to be out from a nut
--Scott
http://wertel.eng.pro
RE: Standard for how many threads to be out from a nut
RE: Standard for how many threads to be out from a nut
You should have "no more than" to prevent excessivly long protruding fastener ends that could pose a safety hazard (scrapes, head bangs and such), could prevent standard sockets from being used at assembly, and that generally make maintenance a pain.
RE: Standard for how many threads to be out from a nut
RE: Standard for how many threads to be out from a nut
You should also probably support whatever figure you want with a tol analysis.
I'd probably determine my minimum bolt length so I had at least 1 full thread at worst case tolerances and then go to the nearest standard length up which means most of the time in reality you'll have significantly more than 1 or probably 2 threads.
I assume AISC requirement of 'flush' is based on worst case tol stack up, not nominals?
Within reason though the customer gets what the customer wants, if they ask for 3 I'd give them 3 unless I have a really good reason not to.
Out of interest the 2 1/2 figure a lot of you use, is this on worst case or on nominal calcs, or is it for measuring actual joints?
RE: Standard for how many threads to be out from a nut
RE: Standard for how many threads to be out from a nut
thread725-57019: Rule of Thumb - Numbr of Thds 2B Full Strength
thread725-37409: Number of threads pass the nut
Regards,
Cory
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RE: Standard for how many threads to be out from a nut
--Scott
http://wertel.eng.pro
RE: Standard for how many threads to be out from a nut
Naval Ships' Technical Manual Chapter 075
Fasteners
RE: Standard for how many threads to be out from a nut
I got the answer I was looking for.