I have a problem, which hopefully isn't a big one and could be rectified without any big hassles.

Some of the screws which was used too install the servos on my Edge seems too be "loose". When installing the servos I made sure the holes were ligned up with the balsa at the back in the servo opening (that I don't screw one in and it just hangs in the air, but that it actually goes into the wood). Now I have found, paying closer attention, that some of the screws doesn't "tighten" it just rotates and rotates (as if the thread is stripped if I can use that too explain it). You can by any means untighten it and take out the screw and screw it back in without it falling out, but it doesn't tighten the way that you can't turn it anymore - it will just rotate when you have turned the screw completely in.

My question is - how can this be fixed? Would you recommend putting in another thin piece of balsa at the back of the existing wood and tightening the screws into that? or is it not neccessary and that everyone has this on their planes?

I'm just scared that the servos will vibrate loose while in the air. If you pull the servo lightly it stucks too the plane so it won't just come off as far as I know. But I'll rather be safe than sorry.

Thanx

Drop some medium CA in the holes. This will close up the hole a little, and should solve the "keeps on turning issue. You should wick CA in the screw holes during the build to prevent the holes from wollering out. This holds true for all screws that you screw directly into wood on the plane.

You can also, as you said, add a piece of wood under the servo board for the screws to bite into - but use plywood, not balsa

After I drill my small pilot hole into the servo rail I mount my servos then remove them and put a few drops of thin CA into each servo screw hole, this hardens the wood and the threads the screws put into the wood. If you have one spinning already you may have stripped the hole so you can add some thicker CA and try it again.

Korps,

When using a wooden servo mounting plate its a good idea once you have your pilot holes drilled for your servos to harden the wood with CA before installing the screws.

You can install the servos without using pilot holes but the chance of not getting everything straight is much greater. In either case harden the wood!

To solve your problem simply take the screws out and add some CA to the screw area letting it cure before re-installing the screws in place. Tighten the screws taut don't strip out the holes, everything should be fine.

I would glue a thin piece of hardwood, not balsa to back up the current wood. Drill a small pilot hole through the current hole, and through the back up hardwood, 1/16" or 1.5mm, run the screw through it to "tap" it, remove the screw, then put a drop of thin CA into the hole, let it harden, then run the screw through it again. The CA hardens the hole and threads that the screw makes in the wood and will strengthen it. You don't want a servo on any control surface to have loose screws. If the hole has gotten big, you can always fill it with Epoxy, let it harden, then re-drill the holes.

How fancy do you want to get?? I drill out the servos screw holes to 1/8 inch then epoxy in a piece of golden rod into the hole, that stuff wears like iron. I only do this to hatchs or cowles where added strength is needed and/or the screw is going to be removed often but it is also a pretty good fix if the hole is buggered up too bad for the CA to fix.

Thanx for the quick replies!

I will do the CA trick - thank you very much.

All of the above. (Don't use CA to glue the hardwood or plywood unter the existing servo tray.)

What I find when I first drill a 1/16" hole is to run a servo screw in and out a few times to establish a thread pattern in the wood. Then drop a couple of drops of CA into it and run the screw back in and out one time before installing servo. I just use thin CA and the wood not only "hardens" but swells up so tight that using the screws that came with the servo can be difficult. I generally strip the head every time and have yet to locate a small screwdriver that fits them well enough.

Using the allen-head servo screws from RTL Fasteners and a ball driver has made this task so much easier and if you experience the same difficulty I recommend them.

Regards,

Clay

I have Craftsman and Crescent screwdrivers, between the two I always have one that is a perfect fit. Sometimes I use one that looks too large, but fits the screw perfectly. I'm always paranoid about stripping threads or rounding heads. I've done it on a V8 intake, and its a PITA![:@]

Once you try servo screws like these, you'll never use the ones that come with the servos.

http://cgi.ebay.com/24x-Socket-Head-...3286.m20.l1116
or
http://cgi.ebay.com/Servo-Screws-9-1...3286.m20.l1116

Try 'em you'll love 'em.
Paul

As many have said, hardening the wood with some thin CA after establishing threads in the hole works wonders. For those that are already loose, adding wood under the servo tray will do the trick. Don't use balsa, as several have already pointed out. I use pieces of popsicle sticks. Works like a charm and you can cut whatever length you want with a decent size pair of wire cutters. Go to a craft store like "Michaels" or something similar and get a bag of 100. Dirt cheap and you'll find them to be extremely usefull. If nothing else, just to stir up epoxy when you mix it.

Oh....and I'll add another loud voice for socket head servo screws. You don't have to put a lot of down pressure on 'em to keep the screwdriver head from turning in the screw. It will save you a broken servo tray at some point, that's for sure.

Good luck.

Thanx people.

I did it last night, still have too do the two aileron servos though, since I did something else also on the plane which got my frustrated and I ended up braking the plug of the charging lead on the switch (just have too get a new one so it's not that big of an issue - that's what you get for trying too be too fancy when you don't have the experience - but that's how you learn aswell). The servo screws seems too be sitting nicely now - it even screws in more difficultly now. On the two servos I did there is one screw on each which is a bit dodgy - but I'll have a look into that tonight when I do the wing servos. I rather stopped yesterday after the charging lead incident since I know when I get too that point I must just pack up and leave it for a while before continuing.

Thanx for the advice people.

Clay, why should I not use CA to glue in the back-up strip? I'm moving the elevator and rudder servos to the tail on my Big Stik and I was going to put some 1/8" ply to reinforce the balsa. Should I use epoxy?

The hardwoods don't adhere well with CA. The softer more porous balsa (which is a type of hardwood believe it or not) bonds to itself very securely with CA but isn't strong enough to bind a servo screw for very long. So use a strip of hardwood, plywood, popcycle stice, etc to beef up under your servo tray if needed. Ambroid, Gorilla Glue, Wood glue, and epoxy will all be better than CA for this purpose.

Regards,

Clay

OK, thanks for the response. I'll use some 5 min. epoxy.

Geez got too finally go through my whole plane - checking everything and filling up ALL the holes, where screws are used too tighten something, with CA. Almost all of them is sitting like a dream now.

I do have a question though (my logic - not always that good - tells me it shouldn't be a problem at all). There is 2 servos where I screwed the screws in wrongly (the holes were too close too the edge of the balsa. It broke out and the screw is basically not really sitting in a hole. This was because of me being an idiot and trying too finish the plane too fast and not get a drill too do the job. If I'm going too try too move the servo now and make new holes it's going too be a mess since the space I have available too move is too small. I could add another piece of balsa or plywood underneath it, but the screws will not go all the way through with enough clearance on the other side. I want too "tack" the servo with epoxy in it's position. Basically still screwing the servo as you would do normally, but then just for extra secureness "tack" it with epoxy at both sides. Is this a good idea or not? I know that if I ever want too remove the servo's I'm going too struggle, but I'll rather buy 2 new servos which costs R300, than loosing a R 1300 plane because of it

No it is not a good idea to tack the servo's in with epoxy. That will eliminate the damping action of the grommets and the servo's will fail prematurely.

The best thing to do would be to remove the broken wood and replace with new. Also you should not be compressing the grommets to the servo's for the same reasons of vibration dampening.

Silly question but the grommets are those "rubber eye lid things" which is between the screws head and the servo? It makes sense what you are saying jrcaster. I think I'll have too do that then - thank you. Would you use balsa or ply wood for this application. As some said - ply wood will work better for reinforcing it behind the balsa.

I got the answer about what grommets are in another post right now after I posted previous.

But what would you use ply wood or balsa?

On my second hand H9 Tribute the mounting holes are drilled up to 3 mm for two of the 5 servos. I was told just to use cable tie wraps. Is that a bad idea?

Thanks

Cable ties? Yes, bad idea. [:@] Find the proper size screws or modify the mount.

Ok. Why?

Wouldn't the servo be able to move slightly with a tie wrap?

Actually the servos sit very well. They can move just a little, exactly as if you use screws. I have flown with this setup 3 times, and can't see any errors.