Hi Guys
I was wondering if any body could help me ? I have a H9 corsair
that I have completed is there some thing or some way that i can
attach the cowl without those little screws that strip the heads after
removing once or twice. just something to make it easy to put on or off.

I took the advice of a fellow RCU memeber and drilled out the holes and inserted the inner (yellow) portion of a nyrod in the fuse and screwed into them with servo mounting screws.

Works like a champ and the screws don't vibrate out.

I've been using a small allen head screw with built in washer from the LHS and it works great but I bet someone out there is doing something really "trick" on theirs.

If you drill the hole slightly larger than the screw you attach it with, then put a piece of fuel tubing in the hole and then put your screw in. The fuel tubing will act as a "shock absorber" and isolate the cowl from the vibrations. A little bit of nyrod inserted in the wood also helps to keep the screw from vibrating back out. see attached diagram. I've done more cowls like this than I can count and it works every time.

Hope this helps

ken

You're stripping the screw heads? Usually the wood gives out first.

I drill a 1/16" hole and use a servo screw( with the built in wide shoulder). I set the screw in, remove them all and the cowl, then drip a drop of CA in each hole. As they loosen up I re-drip the CA.

I also bit the bullet and got a full set of Phillips Head screwdrivers. #00, #0, #1 and #2. The little Phillips head, especially the servo arm screws, are sensitive to the right size tip. Otherwise, it's just a four bladed reamer.

A grommet from a Futaba servo works really well in place of the fuel tubing because it already has a groove in it to hold it in place on the cowl. It works easier for me than the fuel tubing did.

This is maybe a dumb question but then I never claimed to be a genius.

What is nyrod?


Mike

Nyrod is nylon pushrod. I also use them for cowl screw anchors. If you drill a 1/8" dia hole into balsa or ply, that will be a snug fit for the nyrod, and the friction is probably all you need. However, if you want to secure them more tightly, a drop of thin CA will stick them in pretty tight. I insert the nyrod so just a bit--maybe 1/32"--sticks up from the surface; that way you can drop the CA at the outside junction and not foul the inside diameter.

Nyrod inside diameter is perfect size for the aluminum socket head servo screws from Microfasteners, which are much easier to turn with a hexdriver. Allen head screws for servo installation, cowl attachment, etc. are just no good by comparison. Metal threads biting into the plastic do not vibrate out and don't chew up the wood.

I have tried the servo grommets, and for some reason they disintegrated after not too many flights. I reinforce the cowl around the screwholes, first by CAing a CA hinge on the inside surface where each hole goes. I then epoxy a patch of 2 oz. fiberglass over the CA hinge. Then I enlarge the holes in the cowl to 9/64", so the protruding nyrod nestles inside the hole in the cowl. I've found this method the best I've tried so far--no rattling, no enlargement of the holes.

Mike, the only stupid question is one you don't ask.

Thats what we are here for.
Andy

Thanks, fellas. Now I understand. I've used RCKen's process except that I use a latex - like grommet. That works pretty well to protect the cowling, but it doesn't protect the fuse hole. I'm going to go the Nyrod route that majortom described.

Mike

mirwin,
Take a look at the cowl binders on PSP Manufacturings website www.pspmfg.com. I have these installed on several of my models. They are easy to install, will not come loose and the holes in the cowl will never elongate. A friend told me about them a couple of years ago and I have used them ever since. When the guys at our club first observed how well they looked and worked they started buying them too. I think they can also be painted to match your cowl, but have never had the need to do that. If that is a concern ask PSP just to be sure.

Thanks every one for the replys you have saved me from
another brain cramp again. [LOL]

That looks kinda slick. And simpler to use. Does the flat washer-like piece fit inside the fuselage?

Looks like you can paint them:
"Simply drill existing mounting holes to 5/16" dia. Snap in the cowl binders, and your ready to install your cowl. Small, less than 1/2" dia. Maintains contoured 3/32" air gap between fuse & cowl. Paintable.. Clean lines. "

I ordered some today from psp mfg. thanks again for the tips!

oops

I have to say that I looks like RCKen and Sebo 's solution is the best. I don't see how the PSP cowel binders isolate the coweling from vibration the way fuel tubing or gromets would. Why set yourself up for a future repair of a cracked coweling. How much are the PSP binders? I have alot of spare gromets, fuel tubung and nyrod.

Just my 2 cents.


Darren

The price was I think a little high. It came to 13.00and some change
for the binders and shipping. I'm also going to us nyrod or fuel line
for added protection.

Just checked and they're about $10 plus shipping for 6 of the little things. I'm also concerned that they don't isolate the cowl from the fuse, and they don't appear to do anything to prevent the fuse hole from getting chewed up.

I think I still like RCKen's process.


Mike

The Kyosho AT-6 had a cowl mounting method that did not show at all, and no screws actually went through the fiberglass.

A thin plywood ring gets epoxied inside the cowl, near the rear. Blind nuts are installed in the firewall for socket head cap screws. I attempted a drawing, please don’t laugh too hard.

Carrell, what you're describing is known as a cowl ring, which can be a good solution with kit built or scratch built models, and keeps a clean appearance for scale models, but may be too complicated for many ARF buyers. It's not always easy getting the blindnuts correctly spaced on the firewall interior. I've never seen a laser cut cowl ring supplied with an ARF, but then again high end scale ARFs are not my cup of tea.

A couple more ideas....

.

Some of the "Phillips head" screws running around loose in the hobby aren't Phillips, they're JIS (Japan Industrial Standard ?), and using Phillips bits on those things indeed makes the Phillips nothing more than a four-flute tapered reamer.

'course, I dunno how to tell the difference by looking . . .

Scott14 -

Try it again with a larger .jpg file size - the drawings came out itty bitty on this end.