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#1 Estes Cosmic Interceptor

Posted: Sat, 29 Dec 18, 05:34 am
by Commander
I received an Estes Cosmic Interceptor last year that I purchased last year using a gift card from my Secret Santa at work. I have puttered on it here and there over the past year and should post some pics, but I am too lazy.

#2 Re: Estes Cosmic Interceptor

Posted: Tue, 08 Jan 19, 06:46 am
by Commander
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I thought plastic Nose Cones were supposed to be easier to fill? Well as in much in life, not if you want to do it right.

I scraped the along the mold halves, sanded, then applied some thinned Bondo spot putty, sanded, shot some color (red), sanded, shot some color (orange), sanded, reapplied some more Bondo and shot some color (green). and I'm still not happy with the seam :(

The problem with this nose cone, is I don't want to fill up the detail lines for the panels/cockpit. So I take my dental pick and scratch along the detail lines after every procedure. I know, I'm being way too OCD about these things.

#3 Re: Estes Cosmic Interceptor

Posted: Mon, 14 Jan 19, 02:09 am
by Trident
I read about a great way to fill seams on plastic nose cones —CA. Yep, CA. But you sand it after maybe an hour or so, when it is easily sanded. If you wait for full cure, it’s gonna be rock hard.

Learned this from the blogger Chris Michielssen (Model Rocket Building). Chris recommends Dollar Store CA. You get two little bottles of medium for $1. Dirt cheap, and it works just fine. I like dirt cheap. It took me awhile to find it in our store. It was not with the glues. It was in the Automotive aisle.

You might need a second application of CA, but there is zero concerns about it popping out, like I’ve had happen with putty. Shoot some primer, sand the joint, and if you’ve mastered the technique (which might take a couple nose cones), you’ll have smooth seams, and will be ready to paint.

#4 Re: Estes Cosmic Interceptor

Posted: Mon, 21 Jan 19, 02:30 am
by Commander
I will definitely have to try that with the next plastic nose cone I work on. I typically start by scraping the seam with a X-acto blade, a technique shown to me by the venerable S/Sgt. Bush and which can also be used after you have glued two plastic sections together. The pain comes in filling the depressions. While the Bondo thinned with Acetone produces pretty good results, I have also had some issue with the thinnest layers disappearing. sounds like the CA glue fixes that issue.

Finished sanding down the green.
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#5 Re: Estes Cosmic Interceptor

Posted: Mon, 21 Jan 19, 02:55 am
by Commander
Also have been working on the motor mount. This has eight vanes attached to it which could have been a tedious task to attach except for the use of the Macklin Missile Works small guillotine fin jig.

After attaching with the jig I filleted the joints with the thinned Bondo putty.
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Motor Mount stern close up.JPG
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#6 Re: Estes Cosmic Interceptor

Posted: Mon, 11 Mar 19, 07:17 am
by Commander
Black primer to the nose cone and engine mount.
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#7 Re: Estes Cosmic Interceptor

Posted: Mon, 03 Jun 19, 18:25 pm
by BARGeezer
Coming along nicely! A big problem I had with this kit is the "glue grab" effect when installing the engine mount.
That is amplified with the coupler mount as opposed to just centering rings. I humbly suggest dry fitting first and sanding if necessary to ensure a smooth fit with no binding or tightness. Then use a dowel to lay a bead of glue close to the final forward stop. Or use white instead of wood glue. Cheers.

#8 Re: Estes Cosmic Interceptor

Posted: Fri, 07 Jun 19, 18:12 pm
by Commander
I am concerned about that. Any time you begin to think that you're so skilled that such things won't affect you, bingo, it grabs. :( :oops:

#9 Re: Estes Cosmic Interceptor

Posted: Wed, 26 Jun 19, 22:36 pm
by luke strawwalker
Yep learned long ago you should only use white glue or epoxy on motor mounts. Yellow glue is just too "grabby". What happens is, when it's smeared into a super-thin layer, particularly between two layers of absorbent material like paper tubing, the moisture RAPIDLY wicks away into the underlying paper substrate and the glue "locks up". White glue is much less susceptible to this, although it can STILL happen with insufficient glue or in tight fits that result in REALLY thin layers of glue, or long insertions into the tube with lots of surface area (like the motor mounts with external tubes over the centering rings). Epoxy is the best choice for that type anyway.

White glue has another advantage over yellow glue for motor mounts-- yellow glue can result in the "coke bottle effect" where the tube is "sucked in" as the glue shrinks as it dries, which results in a sunken "ring" around where the centering ring sits inside the outer body tube. White glue does not shrink as much as it dries, so it won't suck in the tube wall like yellow glue, and of course epoxy doesn't shrink either.

While white glue is weaker when exposed to heat, like from operating rocket motors, it takes time for that to occur... the paper casings of rocket motors and the tubes and width of the centering rings, and surrounding air gap between the motor tube and main body tube, are all excellent insulators, so by the time sufficient heat has "soaked" through these parts to the glue joints, the motor should have already burned out and ejected and thus is now fully inert and just "along for the ride". SO white glue isn't really weaker in motor mount applications than the more heat-resistant yellow glue or epoxy...

Later! OL J R :)