MS21042-3 spinning

[coffeeguy]

I'm starting to get to procedures that involve bolts and nuts instead of rivets. Seems like progress. I tried to torque a few AN3 bolts and MS21042-3 nuts, but I think I probably over torqued them. I didn't get an indication from the wrench that I hit the torque value. I tried to back off the nut, but it just spins and won't come off the bolt. Has this happened to others? I'm not sure how I'm going to get the nut off right now, but will obviously junk the bolt and the nut when I do get them apart.

I did order a nice CDI torque wrench tonight, so I'm hopeful it will be easier to use than the POS Harbor Freight one that's going in the garbage.

Jeff

[BobTurner]

Stop! Do not proceed until you figure this out. AN3 bolts call for a lot less torque than many think if doing it by feel. Get a torque wrench and use it for every single nut/bolt. If you stripped the threads it was way over-torqued. You may have to drill the head or nut off the bolt.

[rvbuilder2002]

Yes
Throw away the HF tool and get something decent.

A direct indicating (dial) type is best for low torque values but the CDI will work if you learn how to use it properly.

At low torque values (like we use for AN3 bolts) the click is still difficult to feel.

You should clamp a junk bolt in a bench vise and then practice with the torque wrench. Don't practice/learn with bolts that you are installing on on your airframe parts.

[BobTurner]

Don?t forget to measure, then add in, the ?drag torque? when using elastic stop nuts. Probably about 3-4 in-lbs for AN3.

[rvbuilder2002]

Originally Posted by BobTurner

Don?t forget to measure, then add in, the ?drag torque? when using elastic stop nuts. Probably about 3-4 in-lbs for AN3.

That goes for any self locking fastener (as described in Section 5 of the construction manual)

[RV7A Flyer]

I hesitate to ask this, because I don't want it to come out sounding snarky, but it's happened before...

You *are* torquing those AN3s to 25 or so INCH-pounds, right? Not FOOT-pounds?

People have made that mistake in the past, which is why I ask.

And yeah, on a click-type torque wrench it might barely be a click that you can feel, really. I have a set of CDIs including the 10-50 in-lb one, and I like them...highly recommend.

[rv7charlie]

It's pretty rare that the tool is a bigger problem than the operator, even with HF stuff. :-) Perhaps that particular item was defective. Stuff happens. I've got some A/N nuts (came in my -7 kit) with no threads.

The worst thing about click type wrenches is that they go out of calibration if you don't 'go to zero' on the dial when you store them (beam type wrenches go to zero every time you let go).

BTW, you can sometimes remove a stripped nut by putting tension on the joint while turning the nut. If you can get to either the head or the nut with a pair of 'dykes' (diagonal cutters), use them as what amounts to a wedge under the head while turning the nut (or the reverse, if space dictates). You may find that the nut will back off, with the encouragement of tension on the joint.

[Nova RV]

Another possibility is that there is an incorrect washer stack and the nut has passed all of the threads and is on the grip of the bolt. I know I did this once.

[BillL]

Get a KDS2955 beam torque wrench for around $50. It won't go out of calibration and does not cost $300 like electronic or snap-on dial wrenches. Goes up to 60 in-lb. A lot of advantages to a direct readout.

With a screwdriver handle- one can easily apply 30 in-lb of torque YTMV. More than an AN3 needs.

Edit: Maybe less than $300!

[coffeeguy]

Well, that was a learning experience. Got the nut off and the bolt out. I tried using a vice grips to pull on the nut as I was turning it, but it wouldn't back off. I wound up using a dremel tool with a cutoff wheel and that worked very well. I was very careful to not cut anything I didn't want to and because of the washer I was able to cut it off pretty easily. Nicked the washer ever so slightly, so that will be replaced as well. I took a sanding drum and hit the cut edges on the bolt so that there wouldn't be anything to bugger up the hole when I pulled it out.

I was using an inch pounds wrench and yes it could have been bad, but it was probably the operator. I do dial it back to zero too. Did calculate the drag for the fastener as well. I've got to put different fastener values in a table so that I don't have to figure it out every time. Guess that it would get easier the more you do it, though.

I was looking at torque wrenches last night afterwards and ordered the CDI 1501MRMH 1/4-Inch Drive Click Torque Wrench 150-Pound Capacity. I was going back and forth between that one and a CDI dial model. The dial model looked like it might be a little big for tight spaces, so I went with click model. Given what Scott said I might order the dial as well. They are expensive, but to me safety is no compromise. It's a tool, order it! I have a few tools for the 14 tail that I only used a few times.