Screw-Eye into Balsa Nosecone

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Kirk G

Kirk G

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Estes rockets used to come with Balsa wood nosecones (although recently, they've gone more and more to blown plastic nosecones with a molded loop/handle). Other companies still have balsa wood nosecones, and require the use of a small eye screw of about 3/4" to 1" or so threads.

In my most recent kit, it told me to pre-drill a slight pilot hole, or twist the screw-eye into the balsa, back it out, and then put a drop of glue down the hole, and re-insert the screweye... leaving it in place until it dries. That makes sense, but I'm thinking the additional passes in and out tends to compress the balsa wood and possibly strip it more, giving the screw threads LESS to bit on, and rely MORE on the glue to hold it.

My latest nose cone failed to eject well, and the body tube STARTED to zipper, but didn't get very far. As a result, I have to rebuild/repair the body tube and the decal that wrapped around it, and, I have to figure out someway to either insert the nosecone while it's drying/curing to hold the shape BUT NOT GET GLUED IN! Or, I have to remove the nosecone and carry it into the hardware store, looking for SOMETHING of the same diameter to grease up or wrap so that IT can be a space holder while it cures.

Either way, I had to back out the screw eye after it had dried with glue, and I was AMAZED at how easily it came out. It was no where near as strong as I would have expected it to bite, even with the glue.
So, my question is, where do I go from here. Should I find a larger screweye and force it into the hole? Should I paint the end of the balsa nosecone with dilluted wood glue and attempt to strengthen or shore up the balsa (which seems to be very light weight/strength at the exact center of the circle)?

What is the trade-off between weight and size of the screweye? Does a larger one violate the NAR policy of no metal payloads in LPR model rockets?

And finally, how critical is it that the screweye thread into the center of the wooden plug/nosecone...instead of off to one side? Will an off-center screweye affect the balance of a rocket, or affect the recovery any?

Or am I just needlessly worrying about this all?
 
Kirk G said:
Either way, I had to back out the screw eye after it had dried with glue, and I was AMAZED at how easily it came out. It was no where near as strong as I would have expected it to bite, even with the glue.
So, my question is, where do I go from here. Should I find a larger screweye and force it into the hole? Should I paint the end of the balsa nosecone with dilluted wood glue and attempt to strengthen or shore up the balsa (which seems to be very light weight/strength at the exact center of the circle)?

What is the trade-off between weight and size of the screweye? Does a larger one violate the NAR policy of no metal payloads in LPR model rockets?

And finally, how critical is it that the screweye thread into the center of the wooden plug/nosecone...instead of off to one side? Will an off-center screweye affect the balance of a rocket, or affect the recovery any?

Or am I just needlessly worrying about this all?
Click to expand...

Good questions

Did the screw eye pull straight out or did you have to unscrew it? If you unscrewed it then no issue - the threads worked. If it pulled straight out then yes it is a problem, A couple of solutions - get a toothpick and cut/break it the length of the hole. Put a drop of glue in with the toothpick and re-insert the screw eye.

You can use a larger screw eye - just don't go so big that the screw part goes all the way through the nosecone!
The larger screw eye will be heavier, so it will improve your stability but reduce your altitude - although a small increased size of the screw eye should be negligible. This does not violate any NAR rules (again assuming you don't go overboard)

In terms of being centered, again the impact should be negligible. Just make sure you are not so far off center that the screw eye would hit the body tube.
 
The old Estes and Centuri instructions did say to screw the screw-eye into the nose cone, remove it, put a drop of white glue in the hole and then screw it back in. Doing it that way would be less about actually gluing the screw-eye in (white glue will not hold the metal screw-eye) and more about making a dried glue lined tapped hole. I think if you substitute a drop of two of epoxy for the white glue, that screw-eye is not going to go anywhere. This should work even if the screw-eye was ripped out and stripped the threading from the nose cone.
 
I had a screw eye come loose on my Semroc Vega. I drilled a hole for a short piece of 1/4" dowel, glued it in, then glued and screwed the screw eye into the bit of dowel. It's much more solid.
 
I fumbled with pulled out screw eyes in the past. Depending upon the BT size, drill a hole the size of Oak Dowel rod you are going to use. Press it in with wood glue.
Let dry, pre-drill a small hole for the screw eye and screw it in. You shoulf have no problem having it pull out of a Oak wood dowel, even on the end grain.
You could also drill a hole threw the sleeve, then you would be screwing the eye into the side grain.
 
Simplest method, glue the screweye you have back into the hole with more glue then add a good layer to the balsa surrounding the area, kinda like a fillet. You then have way more surface area joining the 2 parts. When they want to separate it's along the glue/wood connection not the glue/metal interface.
 
gna said:
I had a screw eye come loose on my Semroc Vega. I drilled a hole for a short piece of 1/4" dowel, glued it in, then glued and screwed the screw eye into the bit of dowel. It's much more solid.
Click to expand...

I've done this too. Sometimes the balsa just "turns loose" or whatever. Any carpenter will tell you that the END GRAIN is the weakest point to try to drive a nail or screw into (and frequently causing the wood to split on harder types of wood) and doesn't hold well on its own. The glue is there to "reinforce" the connection, as it soaks out into the wood grain. Plus, the threads of the screw eye tend to "cut" some of the wood grain (or at least cut into it) and can lead to easier rip outs, with the cut wood grain simply coming out with the screw threads. The glue soaks into the wood and reinforces the cut bits, gluing them to the surrounding wood grain, helping prevent that sort of thing.

I find that CA hardening the cone really helps with this sort of thing. Makes the balsa MUCH tougher and holds a screw-eye better. If you really want an A+ connection, you can drill the cone a bit and glue in a short piece of wood dowel (1/4 inch or larger) and then screw the screw eye into that. You can also install the screw eye off-center into a new hole. The weight of a typical screw eye isn't enough to bother the "balance" of the rocket. (Heck, when you load the parachute/shock cord and stuff, there's nothing to ensure that the weight remains "perfectly centered" in the rocket, especially on larger diameter rockets, and they all fly fine so long as the CP/CG relationship is maintained correctly).

While it might APPEAR that the screw eye/balsa connection is "weak", IMHO this falls into the category of "if it ain't broke, don't fix it". Personally, I'd just move over a little and screw the screw eye in, (making a new hole), screw it back out, put a fat drop of yellow glue on it, and screw it back in, and call it good.

Later and good luck! OL JR :)
 
It sounds like the hole is fine. With wood and white glue, the eye may thread in and out rather easily. If this makes you uncomfortable, just put a dab of epoxy in the hole before you screw the eye in.
 
On my recent build of the Estes Equinox the kit supplied screw eye had low threads.
The kit screw eye is on the left.

Screw Eyes.jpg

It didn't look like it would hold. I replaced it with the screw eye on the right.

BMS supplies their nose cones with a ridged dowel. The dowel has a small drilled hole for the screw eye.
Much stronger than the balsa alone.

NC Dowel.jpg

I've done a blog posts on screw eye attachment:
https://modelrocketbuilding.blogspot.com/2014/01/screw-eye-threads-tip.html
https://modelrocketbuilding.blogspot.com/2013/04/stronger-screw-eye-attachments-tip.html
 
hcmbanjo said:
BMS supplies their nose cones with a ridged dowel. The dowel has a small drilled hole for the screw eye.
Much stronger than the balsa alone.

View attachment 248635

This is by far, the absolute best method for securing a screw eye, IMHO. Usually I hit the hardware store and buy a whole bag of fluted dowels much like the one pictured. They're long enough to cut them in half for twice the mileage. You will have to drill your own hole for the screw eye though. I usually clamp the 1/2 dowel in vice grips just enough to make a bite, and drill a hole on the flat (cut) side of the dowel. The bit you need to use is smaller than the threads on the screw eye. This way, the threads actually have something hard to bite into. And most of the time, it's already tight enough that gluing isn't necessary. You will of course have to glue the dowel in the nose cone in a hole you drill slightly smaller than the dowel. It needs to fit a little tightly.
Click to expand...
 
hcmbanjo said:
On my recent build of the Estes Equinox the kit supplied screw eye had low threads.
The kit screw eye is on the left.

View attachment 248633

It didn't look like it would hold. I replaced it with the screw eye on the right.

BMS supplies their nose cones with a ridged dowel. The dowel has a small drilled hole for the screw eye.
Much stronger than the balsa alone.

View attachment 248635

I've done a blog posts on screw eye attachment:
https://modelrocketbuilding.blogspot.com/2014/01/screw-eye-threads-tip.html
https://modelrocketbuilding.blogspot.com/2013/04/stronger-screw-eye-attachments-tip.html
Click to expand...

WOW,,, great photos... You've hit the nail on the head, Thanks!
 

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