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Screw eye problem in balsa solved
I was messing around tonight with a really soft balsa nose cone and I needed to put a screw eye into it. Some times I drill a whole and glue in a down. Some times I cross drill against the grain of the balsa and put a dowel in that way.
But tonight I had a slight brian storm. As a box of scrap plywood feel down upon me and hit me, it hit me! Why don't I cut a circle of plywood and glue it to the base of the nose cone? Maybe 2 layers of thin ply. That should be good enough to hold the screw eye in place without effecting the shoulder of the nose cone. So as I wait for the glue to dry, I'm posting this. In hopes that it may help someone else in building rockets of the past and not worry about what we did back then. A drop of glue in the whole never seamed right, and I had many failures because of that. If this works out, not to mention that it can be used as nose weight for making rockets of questionable stability more stabe, this may turn out for me to be common practice. Just thought I'd share. |
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YORF member #11 |
#3
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Woody,
Plywood disks make sense, since you have a large gluing surface. I've never had a dowel pull out of a balsa cone, but I also put a few grooves in the dowel to provide some extra grip. You can use a file, or a Dremel tool, and you don't have to make it very neat, or pretty. Just making it irregularly shaped will help a lot. I do like Doug's idea of threaded inserts, making it easy change any weight you want to add to the nose cone.
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Lee Reep NAR 55948 Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor In the Paint Shop: Nothing! Too cold! Launch-Ready: Farside-X, Maxi Honest John, Super Scamp |
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You can get dowels that are ribbed. I used them with my woodworking when I had my shop.
The excess glue at the bottom of the hole leached up between the ribs so the dowel could bottom out. The perticular nose cone i'm dealing with seam poor quality and soft balsa. I'll be soaking in a titebond thinned mixture to firm it up some. The machine screw is an awesome idea. Thanks for sharing! |
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BMS has a good solution, the ribbed dowel plugs work well.
I've had soft balsa nose cones and came up with a compromise. I screw in the screw eye and remove it. Squeeze some glue in the hole. Three toothpicks are pushed into the hole and allowed to dry. Try to push the toothpicks in as straight as you can. Cut off the toothpicks and sand flat. Screw in the screw eye. Remove and squirt in glue. Reinsert the screw eye again. The only thing to watch for is sometimes the screw eye won't want to go in straight into the toothpicks. It depends if the toothpicks were pushed in straight.
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Hans "Chris" Michielssen Old/New NAR # 19086 SR www.oddlrockets.com www.modelrocketbuilding.blogspot.com http://www.nar.org/educational-reso...ing-techniques/ Your results may vary "Nose cones roll, be careful with that." Every spaceman needs a ray gun. Look out - I'm the Meister Shyster! |
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I've never had a screw eye pull out using the old "white glue in the hole" method other than one violent cato that ripped the screw eye out still holding a big hunk of balsa nose cone. I usually just have the shock cords rip out if the cato is violent enough. If I'm turning a cone that has soft balsa, I usually soak the whole thing with thin CA, including the screw eye mount.
Doug's nut-cert is cool and slick looking for that one go-to rocket that always flies no matter where you go, no matter the size of the field, or no matter how big a motor you stuff in it.
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I love sanding. |
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Wow guy's! That was a trip down memory lane. My middle school shop teacher taught us all those tricks and then some. We built our own launch controllers too! He had been building and flying rockets since the beginning when it all started. I think I still have my launch controller somewhere.
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If it flies, I can crash it! |
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10-12 drops of thin CA glue hardens the threads and surrounding material. We use this in thr R/C plane world for wing hold down bolts, albeit in aircraft birch ply. I've never had a failure using this method, and for extra security, you can add some epoxy on the screweye threads after the CA hardens. Almost as good as the ply being added.
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#9
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A screw eye pulls out from shock load. Either from hitting the end of the shock cord or when the 'chute inflates. Use a longer shock cord and do not attach the 'chute to the screw eye.
I always add 100lb Kevlar of a length equal to the kit-supplied elastic or rubber shock cord. And I attach the 'chute to the shock cord a few inches away from the nose cone.
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Clear skies and fair winds, Mike NAR 31689 |
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Quote:
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Paul If we weren't all crazy, we would go insane - Jimmy Buffett NAR #87246 www.wooshrocketry.org |
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