Hi all, I'm still kind of new to this hobby. I just built my first ARF (GP little toni) and the screws that don't screw into wood on the cowling keep coming out during flight, or for that matter don't even stay. I have been told that I should try and put a small wood block behind the screws but that would be very hard to place inside the airplane. I have already tried CA but that's not working either. I'm thinking maybe if I get some epoxy and put in the screw holes? Any ideas? Thanks!

a very small drop of wood glue. it hardens but you'll be able to remove the screws.

I have used small nyrod material before withe good results. The screws have something to bite into and the plastic material keeps a good grip on the screws.

Dan

I put some gap filling CA then some regular and it seems to be semi hard but I will try the wood glue/nyrod if this doesnt work out.

A small block is the best way to go. Yes it is a fiddly job but worth it.
If you go with epoxy, before you put the screw in - wind the screw into a wax candle then wipe it fairly clean with a paper towel. That way you will be able to undo the screw later.

G'day Mate,
The first thing I would do, is to try & reduce the vibration, balance prop & spinner, & then put wood blocks in, so the screws have something solid to screw into.

Okie dokie, the wood blocks seem to be the answer I get most. The only way I can think of putting them in the airplane is to cut a hole in the firewall and insert them through there. Would this damage my plane in any way?

Best option........wood blocks in epoxy
Next option.......tape over the hole you have from the outside, drop epoxy in from the inside, when dry, pilot the hole again and just thread the screw in fresh again.

Now, for that cowl. I never just screw through it. I drill out the hole with a 5/32 drill bit, then install a round servo gromet it the hole. Now install a screw (it will have to be a little longer now) with the appropreit size flat washer. This 'shock mounts' the cowl by suspending it in the rubber gromets. Screws will rarely come loose, and the holes in the cowl are also protected from wearing larger over time. Also, the rough inside of the cowl is no longer in direct contact with the covering so it dosen't wear on it. You can touch all this up with paint if you like. I do this sometimes depending on the type plane it is. I mount all my cowls this way and have no problems with screws. Dubro makes silicon gromets for this, but most of us have servo gromets laying around that work better IMO because they are one piece instead of halves like the silicon ones.

As mentioned, be sure to ballance your prop and spinner to minimize vibration.

Yup as he said!

You can even use bits of fuel tubing.

I cut a hole in the cowl slightly larger than the tubing. ( Thank's to RCKen for this trick! )...

I then CA the area around the hole to prevent it from cracking.

Then cut a very small piece of tubing, and put this on the screw. Preferably a screw with a big head, or a screw with a washer next to the head.

The screw with the tubing is inserted through the hole and bites directly into the wood, or whatever you are anchoring the cowl onto.

The tubing will expand as the screw bottoms out forming a rather nice anti-vibration mount.

Do this with four screws or more on the cowl.

Works great. When you remove the screws to access the cowl the tubing keeps the washers from falling out too.

listen to allan0899 balance prop and spinner also mount engine snugly,then provide some meat for the screws

I do most all of the above - AND - CA half a CA hinge to the inside of the cowl at the hole. The cowl will not crack unless it decides to take a "dirt nap"

Tricks I use :

Drop of CA in the hole to harden the wood
O-Ring as a washer if vibration is a problem.
Oversized hole, insert wood dowel, drill dowel for screw


Ed :

I LOVE the CA Hinge idea for a cowl...had never thought of that, but will apply it to my current project TODAY. Thanks!

I also like the CA hinge idea. Lots of good stuff here.

There all good ideas!!!

I wish you had a picture of exactly what the screw is going into so maybe I could get a better idea for a fix.

Gibbs

Try using nylon screws with silicone applied to the threads prior to inserting.

That's what I use. 6/32 nylon screws. If you have enough edge margin and can find enough material to tap into, they work great. I've tried all kinds of tricks with washers, grommets, and other stuff but they nylon screws have worked the best.

I've have had to modify the front ends to install blind nuts but I like this Nyrod idea. May try that.

First off,,,use good screws. I like the hex head servos screws Evan sells at [link=http://www.rcaccessory.com]RC Assesories[/link]
After the thin CA has cured in the pre-drilled hole dip the business end of the screw in Shoe Goo and let cure. Have never lost one yet doing this on vibrating gassers.