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using blind nuts/securing cowl
I have a Reactor 1.60 ARF with a DA-50 on the front/fiberglass cowl. Great Planes system is to use screws through the fiberglass and into the wood on the airplane. I did this and it looks and works good, however, I know the engine is going to shake them loose.
I'd like to go to a blind nut set up to ensure longevity with 4/40 bolts. Problem is I cannot get to the back side of the fuselage to insert the blind nut. Has anyone had any experience with putting the blind nut on from the top side/aka the other way around? I could peel back the covering and secure the blind nuts with 30 minute epoxy on the outside. Dunno if they will come loose or not doing it this way as the bolt would now be pulling against the nut, however, between the epoxy and lightly tapping the nut in place in the hard wood, I do not see an issue. thanks, Mike |
RE: using blind nuts/securing cowl
Hey Jigeye. How about either of these. The first one is from Great Planes GPMQ3360 4-40 Threaded Inserts 4 pcs. Or maybe these from Du-Bro http://shop.dubro.com/p/e-z-mount-co...-size-aircraft They have two sizes.
Another option is to build your own mounts, from some light ply, and put the blind nuts on the correct side. Just another thought. |
RE: using blind nuts/securing cowl
If the existing screws go into hardwood, the threaded inserts will work well if installed as directed and secured with epoxy
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RE: using blind nuts/securing cowl
ORIGINAL: jigeye I have a Reactor 1.60 ARF with a DA-50 on the front/fiberglass cowl. Great Planes system is to use screws through the fiberglass and into the wood on the airplane. I did this and it looks and works good, however, I know the engine is going to shake them loose. I'd like to go to a blind nut set up to ensure longevity with 4/40 bolts. Problem is I cannot get to the back side of the fuselage to insert the blind nut. Has anyone had any experience with putting the blind nut on from the top side/aka the other way around? I could peel back the covering and secure the blind nuts with 30 minute epoxy on the outside. Dunno if they will come loose or not doing it this way as the bolt would now be pulling against the nut, however, between the epoxy and lightly tapping the nut in place in the hard wood, I do not see an issue. thanks, Mike I use both #8 and #10. Even after removing a cowl or other cover several times for maintenance they still hold well. No worry about a blind nut leaving its home. |
RE: using blind nuts/securing cowl
if you use thin CA to harden the holes they will last for many years regardless of engine size, one thing to watch for is the holes in the cowl auguring out because of vibration, a good remedy for this is to use scrap CA hinge material epoxied to the inside of the cowl at the screw locations
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RE: using blind nuts/securing cowl
I use threaded inserts. Thread the insert in the wood,then I take them out and re insert with epoxy. Theses can be found at your LHS,lowes or ace hardware. I use rubber washers/grommets with the Cowl screws (cap head). Bob |
RE: using blind nuts/securing cowl
I don't want to appear soft minded here, but can any of you post a picture to show what/how you did this? I can see multiple applications for this type of method of securing things to the fuselage.
Horace, can you post a picture of that screw you are talking about? That may help us find them at the HW store. Thanks. CGr. |
RE: using blind nuts/securing cowl
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I agree that hardening the threads with thin CA will make the holes last a long time.
Here's something else you can do if you're not happy with that solution. Take the yellow inner portion of a nyrod pushrod. Drill out the hole so the nyrod fits snugly inside. Scuff the nyrod and expoxy it into the screw hole. Install the cowl with self tappping screws and (here's the secret for getting screws to stay put on gassers) use rubber bonded or sealing washers on the screws. RTL Fasteners sells the bonded washers in various sizes. |
RE: using blind nuts/securing cowl
Hey Barracuda. So the nyrod would go into the fuse, or firewall. And then get drilled to accept the self tapping screw? So now the self tapper is into nyrod instead of wood? Just want to make sure. http://www.rcuniverse.com/forum/js/f...ssed_smile.gif
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RE: using blind nuts/securing cowl
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RE: using blind nuts/securing cowl
ORIGINAL: kwblake Hey Barracuda. So the nyrod would go into the fuse, or firewall. And then get drilled to accept the self tapping screw? So now the self tapper is into nyrod instead of wood? Just want to make sure. [img][/img] No drilling required, just screw the self tapping screw into the hole in the end of the nyrod. |
RE: using blind nuts/securing cowl
ORIGINAL: CGRetired Horace, can you post a picture of that screw you are talking about? That may help us find them at the HW store. Thanks. CGr. |
RE: using blind nuts/securing cowl
ORIGINAL: CGRetired I don't want to appear soft minded here, but can any of you post a picture to show what/how you did this? I can see multiple applications for this type of method of securing things to the fuselage. Horace, can you post a picture of that screw you are talking about? That may help us find them at the HW store. Thanks. CGr. Ive used these and "thought" that was what was being discussed here. What I use to hold the wing struts on my 92" gas cub. Scroll down to where it says..."Threaded inserts". Basically is like one of those screw in drywall screw inserts that is threaded on the outside to screw in, then threaded on the inside to accept a screw. Obviously you would need thick enough material to screw in to use these. In the cub wings I had balsa block inside the wing to attach to. http://www.greatplanes.com/accys/gpmq3300.html |
RE: using blind nuts/securing cowl
I use Barracuda's formula but I add another step. I beleive medium fuel line is 3/32 OD. So I drill a 3/32 hole in the cowl where the screws go through. Then I slice off a piece of fuel tubing just long enough to protrude from both sides of the cowl. These should press fit into the holes with a little protruding from both sides. When you run your screw into the nyrod, the tubing will expand on both sides of the cowl and become just a bit larger than the original 3/32. You now have an isolation mount with no metal touching the cowl. You don't tighten the screws really tight, just tight enough to expand the fuel line.
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RE: using blind nuts/securing cowl
Hmmmm ... I'm going to have to think about that one.
http://www.booksstore.info/11k/bass.jpg http://www.booksstore.info/jokelist/boa.jpg |
RE: using blind nuts/securing cowl
ORIGINAL: JollyPopper I use Barracuda's formula but I add another step. I beleive medium fuel line is 3/32 OD. So I drill a 3/32 hole in the cowl where the screws go through. Then I slice off a piece of fuel tubing just long enough to protrude from both sides of the cowl. These should press fit into the holes with a little protruding from both sides. When you run your screw into the nyrod, the tubing will expand on both sides of the cowl and become just a bit larger than the original 3/32. You now have an isolation mount with no metal touching the cowl. You don't tighten the screws really tight, just tight enough to expand the fuel line. |
RE: using blind nuts/securing cowl
The threaded inserts will work fine, but it's overkill. It's not like a cowling has flight loads on it. The inserts are strong enough to hold wings on (assuming the wood they are threaded into is strong enough) so putting them on a cowl is simply more effort than is required. A hardwood dowel glued into the balsa with the screw hole drilled into it and then the threads hardened with CA is quicker and cheaper and still strong enough to never get loose or pull out.
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RE: using blind nuts/securing cowl
Another for Barracuda's method. Never had a screw lost in 15 years. Sometimes you have to add some wood to the back, but thats no big deal. I started using the rubber bonded washers a couple years ago and really like them.
Edwin |
RE: using blind nuts/securing cowl
You got a lot of good advice already. But if you want to do the blind nut way. I have put a wire through the hole and fed it through to where I had access. Then slipped the blind nut on and put a loop in the end of the wire. then pulled the wire back the other way till the blind nut started. Cut the wire and quickly started a screw in the blind nut so it could be seated. Then shook the plane to get the wire end out. It's not a perfect way, but it will work. This is assuming there is an opening to get access to the wire.
David |
RE: using blind nuts/securing cowl
Thanks for the many helpful comments. Nice people here. I think I will stay with the screws and use the washer setup shown with the inserts inside the cowl.
Thanks again, Mike |
RE: using blind nuts/securing cowl
ORIGINAL: daveopam You got a lot of good advice already. But if you want to do the blind nut way. I have put a wire through the hole and fed it through to where I had access. Then slipped the blind nut on and put a loop in the end of the wire. then pulled the wire back the other way till the blind nut started. Cut the wire and quickly started a screw in the blind nut so it could be seated. Then shook the plane to get the wire end out. It's not a perfect way, but it will work. This is assuming there is an opening to get access to the wire. David Braided wire works great. Dave's system works, but I use a wheel collar and don't have to do anything special. The smaller the collar the better but no matter the size they can easily be made to lock onto the wire. They hold so tight you can pull hard to seat the Tnut. With the nut seated, back the wire out. Run the bolt in and tighten and your wire is ready to do the next nut. The security of a Tnut is hard to beat. If you've got an OS engine, you've also got the perfect collar to use. They supply them and a short length of braided wire. |
RE: using blind nuts/securing cowl
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Hi!
Best way to secure a cowl is to bolt it to the firewall trough the front opening using sheet metal screws! No using bolts trough the sides! |
RE: using blind nuts/securing cowl
ORIGINAL: daveopam You got a lot of good advice already. But if you want to do the blind nut way. I have put a wire through the hole and fed it through to where I had access. Then slipped the blind nut on and put a loop in the end of the wire. then pulled the wire back the other way till the blind nut started. Cut the wire and quickly started a screw in the blind nut so it could be seated. Then shook the plane to get the wire end out. It's not a perfect way, but it will work. This is assuming there is an opening to get access to the wire. David I cut off the screw head from a screw that matches my most often used blind nut sizes. I soldered that to the end of mult-strand wire steel wire ( getting the solder joint just right is annoying, but worth the effort ) so that I can drop a nut and screw it onto the remaining bit of screw from the wire side. Now I fish the screw through to the access point, screw on the blind nut, and pull it through. Once the blind nut is in place I drop a washer and matching nut to the protruding screw portion and "pull" the blind nut into place by turning the nut. Finally I merely loosen the nut and turn the wire to extract the remaing piece of screw. Making this "tool" the first time is a bit of a bother, but it up being oooh so useful from then on. |
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