To Fill or Not To Fill...

 The Thrifty Rocketeer blog continues...

Other than which glue or paint to use, one of the most frequently debated topics is "Should I fill the spiral grooves on my body tube or just ignore them?"

There are several schools of thought on this.

If you're a perfectionist, or committed to a scale model, the answer is probably "Yes, fill the spirals!"

But if you're a weekend sport flyer who crashes and rebuilds almost as fast, you might be willing to overlook that faint line spiraling around the body tube, under the fins and launch lug, all the way to the top.

But the next question is one of the hardest...or softest.. depending on what material you're working with.

Nobody likes to sand. Oh, your buddy may tell you that he spent hours sanding and dusting and priming his surface to get it mirror smooth, but let's be honest... unless we're retired or have hours to while away, nobody likes to sand for long.

As a result, most rocketeers (but not all) will recommend a filler that sands easily and smoothly, drying fairly quickly, but then sanding down easily.

Now, you may be concerned that if the filler is that soft, how can it hold up to any flexing... and it's a good question.  Some fillers have a little latex added in them, and others have no plastic, but almost all plaster and cake.

This means, if you fill with wood filler, you just may see cracks or chips fall out of your rocket if your body tube is so thin that it easily flexes.  On the other hand, if you layer it, and seal it, and prime it, and paint it....  you may never see a problem.

Recently, I asked about what the best filler might be, as I acquired a black 3-D printed nosecone, and while a beauty, it does leave a lot of grooves or ridges in the construction process.  If I were just to fly the rocket, I'd let it go au naturel, as it matches the body tube and is kinda cool as is.

But there are a few white decals that need to adhere to the nosecone for effect...and so a smooth surface is desired.

I asked my rocketeer friends what they suggested, and I got a range of answers. A couple of years ago, the primary answer was "Elemer's Wood Filler" paste in a small Tupperware tub. An earlier version of it comes in a tube. 

About a year ago, Tamiya brand white crack filler was suggested in a tube, and I've tried that. (It dries amazingly fast to your finger and on your plastic model that has a ridge or seam that you're trying to glaze over. I bought a tube for almost $9 at a hobby store last year.)

But this week, the most common answer I got was Bondo Glazing and Spot Putty, available at Auto parts stores, Wal-Mart and several other sources.  When I asked on-line in a Zoom meeting, no less than three people held up the half used tube to the camera and swore by it.

So I hunted down on line a tube, and found two setting on the Wal-Mart shelf. (Unfortunately, this Walmart had closed at 10pm, and I was there after midnight, but that's another story.)  The odd thing about this is that the packaging has a very slight difference between the picture above, and my package... a "stage number" in the upper right.  The picture says "3", but my package has a green "2".  Now, I don't think there's that much difference in the product, as it will do what it says, but I suspect the photo I found is from an auto finish dealer, who might have three stages to get to this point, rather than the casual rocketeer.

I'm about to break out my fast drying Bondo glazing putty and try to coat the nosecone smoothly and without lumps... They warn me to use a plastic spreader, so this may be a challenge on a dome surface, but I'll let you know how it goes.  

Oh yes, and they warn you due to California regulations that this product can cause respiratory and reproductive harm, so use in a ventilated area and you might think about nitrate gloves, since they are so common these days.

I'll let you know how it goes.

This has been the Thrifty Rocketeer spending $3.17 for a tube of filler to smooth my grooves out.