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Torque wrench needed for phillips head screws?

ymc9

ymc9

Member
The forward skin is attached to the V stabilizer with AN5 philips head screws. Do you use a torque wrench to fasten them? I tried it a bit but felt it quite difficult to hold a screwdriver bit tightly with a wrench.

Also, if a torque wrench is to be used, what torque value should be used for screws? Is it the same as the same size bolts? AN5 bolt's torque is 100-140, which feels like a lot to me ...

Thanks in advance!

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Those aren't AN5 bolts. They are AN507 screws. Those particular ones are -8 machine screws. if you torque those at all, they should only be torqued to about 8-10 inch lbs.
An AN5 bolt is 5/16" diameter.
 
I see; thanks for the education! That explains why they don't look any similar to AN5 bots at all 😂.

I guess instead of worrying about the torque, the main goal should be to screw them in so they sit flush into the dimples, right?
 
ymc9 said:
I see; thanks for the education! That explains why they don't look any similar to AN5 bots at all 😂.

I guess instead of worrying about the torque, the main goal should be to screw them in so they sit flush into the dimples, right?
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I haven't built an RV12, but in the print you show it looks like they just go into a bunch of nutplates to hold the dorsal fairing on. If that's the case, they just need to be snug.
 
wirejock said:
If you really want to go down the rabbit hole, buy a CDI torque screwdriver. It measures down to 5 in/lb. I use it to measure running torque on nylocks.
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I saw it and it's gonna be another expensive toy in the toolbox. I'll probably wait until I have to own one 😄.
 
Buy yourself a good phillip head screw driver with a short big grip. Surprisingly Harbor Freight more expensive soft grip screw drivers are very good, almost as good as SnapOn.

For quick screwing jobs, I have a battery power ratchet wrench and a good phillip head socket. This tool makes quick work on the screws. The impact driver screws too fast. The battery power ratchet makes the ideal speed and it doesn't turn the screws too fast to heat them up.
 
You’ll want a torque screwdriver when installing the screws in the rear window. I got the FIRSTINFO H5178 on Amazon. They’re less than $80 now and it worked great for me and two other 12 builders that borrowed it.
 
Yep - -FAT torque handle from Wheeler Engineering
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WHEELER ENGINEERING FAT WRENCH 2023 EDITION | Brownells

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More (and less) than you might think. Just a spring, ramp and snaps when reached. I have checked on the bench and matches my little beam OK. From some testing the screws can take way more torque than recommended so with this tool you won't snap any and still be able to remove them.

Search for it and a location/price acceptable, this is just one link.
 
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PhatRV said:
For quick screwing jobs, I have a battery power ratchet wrench and a good phillip head socket. This tool makes quick work on the screws. The impact driver screws too fast. The battery power ratchet makes the ideal speed and it doesn't turn the screws too fast to heat them up.
Click to expand...
Be very careful about using even a powered ratchet on screws or bolts. We had a problem for months, with screws and bolts galling up in nutplates during new aircraft builds. After several months of experiments, Process Control finally determined that anything but hand turning speed had the potential for heating the hardware up enough to start melting off or drying out the vendor applied lubrication. They even went down to under 50 rpm on the torque limited screw guns and still had the problem show up. Most of us at work are so used to using speed handles to run fasteners in and out, we have to remind ourselves to slow down the rate we turn them, or they get so hot in just a few turns that threaded area will burn your hand.
 
Whenever I close up a panel I put all my screws in a cup and spray them with either WD-40 or a corrosion compound so they'll come out easier next inspection. I use either a ratcheting screwdriver or a screw gun with adjustable torque settings.
 
I like to run in the screw with a low speed drill/driver to a few turns short of snug. Final tightening by hand. And I’ll second not much torque required for tight. These screws tend to be brittle and easy to snap the heads off you you use too much torque.
 
Alternate method for torquing screws: 1/4"-drive torque wrench set to the proper torque setting. To that, attach a 1/4" socket and insert the appropriate screwdriver bit. Easy peasy lemon squeezy! ;)
 
According to the AN507 specification, page 4, the carbon steel screws, which these are, are heat-treated to at least 50 ksi. This is very low. Be careful not to over-torque them or strip their heads.

Dave
 
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