Metric or UNF

[shaqra]

At the weekend I was discussing about changing my rigging after the season, from
the present 5/16 UNF to Metric (M8) However an elder said I should keep the UNF as it was a better thread. What does the forum think? Tks

 

[jonathankent]

What do you mean a better thread??

I assume you are refering to the stainless wire, and in which case, how does thread have a bearing on this.... its 19 wires twisted together.

 

[shaqra]

I mean the the threaded terminals that are swaged to the wire.!!

 

[savageseadog]

Some of the rigging screws I've come across are UNF. The value of a fine (close pitched) thread is that it helps to tighten the rigging. o maybe that's why someone said it was better but I'm not sure if UNF is finer than the nearest size metric fine thread.

 

[VicS]

[ QUOTE ]
but I'm not sure if UNF is finer than the nearest size metric fine thread.

[/ QUOTE ] 5/16 UNF is 24 tpi which is a pitch of 0.04167"
M8 has a pitch of 1.25mm or 0.0492" (which is equivalent to approx 20 tpi)

Both are 60º threads (compared with Whitworth and BSF which are 55º)


There is also a fine metric thread series in which M8 has a pitch of 1.00mm (about 25tpi)

 

[Salty John]

The manufacturers show no difference in turnbuckle breaking strength between metric and UNF thread.
If you intend to change all your turnbuckles you might as well go metric for ease of replacement in the future.

 

[shaqra]

Thanks all for your replies. The gentleman I was speaking said it was less likely for the threads to strip/pull in a hard blow using UNF. However it appears there are no real issue's between both different types.
So metric may be the way to go as js48 suggests.
Regards