Last few times flying my propprop nut has come loose. I’ve tightened it and also had others tighten it to be sure it was as tight as it could get, but it keeps coming loose. Even have a locknut on it. It’s a four stroke, and I’ve been told it’s because of the kickback. I don’t really care why, I just want it to stay tight. One suggestion was to get an aluminum spinner & plate, and that next on my list things to try. Is there any reason I don’t just give the nut and prop some ca or epoxy ? I know it’ll be tough to remove, but that’s the point. Any ideas or suggestions. Thanks

Rather than CA or epoxy I might try some Loctite. You can always break loctite down with a little heat, if necessary.

Like Norm said use loctite the blue stuff 242 or you can double nut it with one of the nuts a locknut.

You say it's loosening the prop nut right? Is it throwing the prop violently when it happens or are you just noticing that it's loose. The reason I ask is because fourstrokes tend to backfire or predetonate during lean runs. This causes the motor to "kick back" thus throwing the prop violently. I have had it happen more than I care to remember on my saito 72. If this is the case try richening your needles a little.

I asume that the nut is not bottoming on the thred? also does the prop drive plate have good grooves/hatches i it? to undo the nut like that the prop has to be moving, a backfire will not loosten the nut on its own, its using the inertia of the prop, try using a washer made from roughsand paper on either side of the prop.

Actually woodsy, if you want to get specific it is centrifugal momentum. P=mv

My Saitos come with a lock nut. I get a large, flat washer, and 2 nuts. If you didn't get this with your 4 stroke, try to get another nut. Tighten the first nut real tight against the prop and flat washer. Hold this nut with a wrench, and install the 2nd nut. Run it tight against the first nut using another wrench. If your spinner uses a "center bolt" to hold the cone on, it can be used as the 2nd nut. I have 4 Saitos and have had some backfires while starting. I have never thrown the prop....... although one did loosen up ONE time. I also use Harry Higley's Lite Loc on a couple planes. It is a large, flat nut, about 3/16's" thick, made of aluminum. (he also makes a heavy model of brass). I use this right against the prop, and then use a prop hub nut run up tight against the flat Light Lock. I have never had a prop loosen on my .56 Saito all last summer with this set up. Of course...... check for a lean situation first like someone else mentioned......lownslo

From a beginner to a beginner: I had the same problem. I believe that the problem is with the size of the nut that comes with most engines (it is tiny). Go to Tower's website and look at hubs from Harry Higley http://www2.towerhobbies.com/cgi-bin/wti0095p?FVPROFIL=++&FVSEARCH=harry+hub&FVPROFIL=+ +
These are large nuts (not trying to be funny) that you can really crank down onto the prop with a socket wrench (just grab that blade with a glove!)
This will solve your problems, unless you need/desire to use a spinner. ps you will need the proper rubber insert for your electric starter if you use these types of hubs

that link might have been bad; try this:

http://www2.towerhobbies.com/cgi-bin...?&I=LXL746&P=7

Paul_c.... gave you the link for the prop hub like I mentioned in my post above. I am adding the Lite Lock URL from Tower, like I also described in my post above. It, used in conjuction with the prop nut works great!! ...lownslo

http://www2.towerhobbies.com/cgi-bin...?&I=LXL744&P=M

PS... I ordered a catalog from Harry Higley. It looks like Tower doesn't handle all the sizes that are available. He has all kinds of cool stuff. I ordered directly from them.

hey lownslow, i'm going to get that light lock--Harry Higley stuff is great (including his books)