Torquing nuts on spars

[blueisthenewblack]

Thank you, Rick and Glen! I will go with the beam torque wrench and forgo the click-type. I will definitely practice getting the torque right on some scrap first before going to the spars.

[GlenNJ]

Stephen,

I also used a beam torque wrench like the one Rick mentioned, and used the same technique he did. I don't know how you could measure the friction torque with a "clicker" torque wrench.

Glen

[at7000ft]

Stephen

Used an old fashioned beam type wrench:
https://www.amazon.com/Neiko-03727A-4-I ... nch+pounds

I noted the friction torque while tightening the nut before it made contact with the washer (usually around 8-10 in-lbs for the AN3s) and added it to the 20.

Rick H

[blueisthenewblack]

Hi all,

I'm getting ready to install the fasteners (bolts and rivets) for the spars.

For torquing the nuts, the torque info. in the build manual instructs to measure the friction torque of the nut first:
https://flywithspa.com/docs/pbm/toc453317739.html

And add the desired torque to reach the final torque. On the spars, for the AN365 nuts w/ 10-32 threading, the desired torque is 20-25 in.-lbs., not to exceed 25 in.-lbs. maximum shear (assuming I decoded everything correctly in the plans/build manual).

This implies that I'd need a torque wrench with a scale on it to measure the friction torque, like this:
http://a.co/abxLpdU

I don't know if the scale type is accurate enough for the final torque, though. This CDI (SnapOn) torque wrench is supposed to be of high quality, but costs considerably more:
http://a.co/3wzoJlL

I'm just wondering what others did when torquing.. did you use a click-type wrench and just set it to 20 in.-lbs.? Or did you measure the friction torque first (and how did you measure it)?

Thanks!
Stephen