How to best smooth this plastic Estes nose cone?

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MichaelRapp

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Hi all,

I primed my Baby Bertha the other night, but really hadn't taken a close look at the nose cone. The cone is obviously formed by joining two halves together. In my particular cone, these halves seem to have been offset just slightly. There is a ridge and crease all along the middle of the cone:

photo 1.jpg

For the ridge part, some generous sanding will probably take care of it. What is the best way to handle the crease/indentation? Should I just apply a really, really, thick coat of filler/primer and sand it down smooth?
 
I'd sand it.

Start with 220 grit and a wood sanding block of some kind. Then to 320, 400, 600. If it is still a bit dull at 600, you could go to 800.

Should be able to finish it in about 30 minutes.

Greg
 
As far as the indentation goes ... is the plastic styrene or something else?

Greg
 
I always sand the crap out of the nosecone lines before primer goes on. You can use a fairly rough sandpaper to do it and it'll only take about 15 minutes. Be sure and sand the entire nosecone, not just the lines. Make the surface even all the way around it and you'll have a uniform finish.

After you sand the plastic, give it a coat of primer. Sand the primer with rough sandpaper to where there's a lot of primer gone, and a lot of nosecone showing. Then another coat of primer, and sand that one with a fine sandpaper without letting any of the nosecone show.

If you follow up with a very fine grit of sandpaper you'll end up with a nosecone that looks like smooth plastic.
 
Run a line of thicker CA through the crack, this will fill in any divots or misalignment's. Then after curing sand it like crazy. Use whatever grit sandpaper feels right as long as you finish with a high grit for the smoothest finish.
 
I would sand once, hit with plastic adhesion promoter, squeeze in Bondo Glazing and Spot Putty, then repeat the sand and prime cycle to satisfaction.
 
I like Squadron putty (either white or green) to fill with before sanding. Most hobby shops have it in the plastic model section.

+1 on the putty. I have Tamiya (it's what my hobby shop carries). It dries quickly and sands down smooth. Since finding out about it, I use it on all my nose cones.

Here I am using it for the first time. I could have sanded the ridges down more before using it, but it worked really well. I tested it on the shoulder before doing the nose cone, just to make sure I knew what I was doing.

IMG_1547.jpgIMG_1552.jpg

Now I'm more rigorous about sanding off the ridges of flash, and don't have to use as much putty.

Sand ridges, putty indentations.
 
I've had good results with the Bondo Spot Putty on top of Primer too. Sometimes I even use JB Weld as a Filler for small seams because it sands down so nicely and consistantly.
 
I typically fit a dowel rod into the base of the cone to the tip, tape to the tapered area, and the other end of the dowel into a cordless drill.
Turning in the direction so you sand into the high side of the seam, start at the tip of the cone holding sandpaper in your palm and squeeze gently and run down to the base of the cone. Helps keep the dowel centered in the tip of the cone. Few coats of primer takes care of anything else. I never go finer than 220 to prime.
 
Fill any divots with your filler of choice. Then "paint" the entire exposed nosecone with a Sharpie. Wet sand until it's mostly gone with 220 grit, then again with 320. Prime, paint.
 
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I hate the misaligned mold halves issue, but it's not too hard to deal with. I file it, sand it, primer, then spot putty, repeat last two steps if needed. No more problem...if you are good with the file it makes things go a lot quicker than by sanding.
 
+1 on the putty. I have Tamiya (it's what my hobby shop carries). It dries quickly and sands down smooth. Since finding out about it, I use it on all my nose cones.

Here I am using it for the first time. I could have sanded the ridges down more before using it, but it worked really well. I tested it on the shoulder before doing the nose cone, just to make sure I knew what I was doing.


View attachment 249108View attachment 249109

Now I'm more rigorous about sanding off the ridges of flash, and don't have to use as much putty.

Sand ridges, putty indentations.

I have been using Tamiya Putty for the past 10 years followed by one -two coats of primer sanded to 600 then I use a flat white and sand again( not necessary for darker colors) then spray on top coat.
 
Run a line of thicker CA through the crack, this will fill in any divots or misalignment's. Then after curing sand it like crazy. Use whatever grit sandpaper feels right as long as you finish with a high grit for the smoothest finish.

Ditto!
 
You can also use a razor blade to scrape along that seam, sand to 220, then prime and sand. Usually goes pretty quick, and works pretty well!
 
Final 'sanding' should use a Scotchbrite pad after a final coat of primer.
 
Where does one find Tamiya filler out here in the wilds of rural America? and why is it called that anyway? Somebody's daughters name?
 
Tamiya is the name of the company. don't know where/when they started...but it was at least 30-40 years ago. they sell a wide range of plastic/resin models and associated products. if you can find a hobby shop that carries plastic models that would be a good place to start :).
Rex
 
The cone is obviously formed by joining two halves together. In my particular cone, these halves seem to have been offset just slightly. There is a ridge and crease all along the middle of the cone:

This cone was made using a process known as blow molding, as are the majority of plastic nose cones found in model rocket kits. In the blow-molding process a pair of mold halves are brought together around an extruded tube of molten plastic called a "parison." Once the mold halves are in place, hot air is injected into the parison, which expands to fill the mold cavity. After the part cools a few seconds, the mold halves are separated and the completed part is removed.

The ridge is due to either an old mold, an improperly engineered mold, an improperly set up mold, or some combination of the three. Here's a short video I put together describing the process:

[video=youtube;XTCRCYjOF8Y]https://www.youtube.com/watch?v=XTCRCYjOF8Y[/video]

James
 
This looks like a job for Kruger Industrial Smoothing.

or you can sell the rocket and donate the money to The Human Fund.


:wink:
 
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