Fix for doubles band bolt - anybody see a problem with this?

[Peter_C]

FWIW a simple hand file can clean up the cut edge of the bolt in less than a minute.

If it were me, I would just cut the bolts. Of course I would also be using air tools.

 

[Captain12Pk]

I've had simillar concerns; my bolts being longer than what would be considered optimal. So, necessity being the mother of all invention (and having a machine shop at my disposal), here's what I came up with...

Proper length bolts are obviously the "best" solution, but this way I can use slightly longer bolts and not have to worry about different "V" weight designs not fitting. I also have no concerns at all about catching or ripping my drysuit.

Happy diving.
K

 

[Lobzilla]

Not that this is requires anywhere near maximum, but it usually works out that a UNC (Unified National Course in the US) bolt requires at least two full threads past the end of a standard nut to achieve the rated load. The counterbore on the Delran nuts in the OP’s photo accommodate that without projecting outside the plastic.

Akimbo,

I learned that the 'two threads past the nut' rule is to assure that nylock (self-locking) nuts are secure and that only the first couple of threads inside the nut really bear the load.

(Source: Engineering school and aviation mechanic's course)

Edit: Here is a nice look at threaded fasteners; last page has load distribution.

 

[Akimbo]

Akimbo,

I learned that the 'two threads past the nut' rule is to assure that nylock (self-locking) nuts are secure and that only the first couple of threads inside the nut really bear the load.

(Source: Engineering school and aviation mechanic's course)

Edit: Here is a nice look at threaded fasteners; last page has load distribution.

I got it years ago from a report (NASA I think??) based on destructive testing/stain gauge tests, either the bold snapping or the threads stripping. It varied a lot based on material. You would expect that since the nut dimension/number of engaged threads are not material dependent.

I believe that A-36/mild steel and 304 stainless peaked at two threads while some of the heat-treated grades were one thread or less. I didn’t pay any attention to all the different flavors of Aluminum. I don’t remember exactly what thread diameters they tested, but it was larger — in the ¾-1” range. In the end, none in this test report showed that more than two threads had any benefit. I do remember that the rolled threads performed better than the cut threads, especially in 300 series stainless.

It would be interesting to see actual test data over a much broader range of materials and sizes.