Filling Model Rocket Plastic Nosecone Cast Marks
Classic plastic rocket nosecones, used in the lower levels of High Power Rocketry (HPR), always have that pesky little edge of plastic left over from the casting process, marring the otherwise pristine shape we know and love. Dealing with those cast marks is purely a matter of preference. At such low speeds and payloads, it really doesn’t matter. Nevertheless, we at One Way Rocketry always want our nosecones to be symmetrically perfect, even if that goal is unattainable.
“Have no fear of perfection, you will not reach it.” -Salvador Dali
It doesn’t really matter, at such low speeds and low altitudes, exactly how “smooth” we make our rocket’s nosecone. However, if we hope to make an amazing finish on our HPR rocket for a beautiful launch, or for display, or even for marketing purposes, we think the following technique will “fill the gap” in attaining perfection in our nosecones.
Testors Craft – Dimensional Craft Paste
The engineers at One Way Rocketry tend to use and recommend Rust-Oleum products. They tend to offer “near-commercial” paints at many locations, making it relatively easy to find for most modelers. And they own the Testors brand, long-known for high-quality model paint. Testors makes “Dimensional Craft Paste” which claims “adds dimension to your project,” and includes little assistance aside from that. The bottle essentially says “apply with thick brush or pallet knife.”
We decided Dimensional Craft Paste is “Bondo” for Model Rocket Nosecones.
We indeed used a pallet knife, and find it takes ever so slightly more than zero product to fill the usual trough left by trimming away your cast marks. One of these craft paste bottles should, thus, last a lifetime; unless you’re prone to eating your glue.
After deciphering their very terse label a bit more, we decided it is safe to smear the paste directly on your soap-washed and dried nosecone, without any kind of primer. Definitely leave it to dry overnight; if you try to sand it too soon, little dough balls form, just like Bondo, wasting the application and clogging your sandpaper. We like plain, 400 grit sandpaper for hand-scuffing the paste after letting it dry overnight.
After Bondo-ing our nosecone, we found it doesn’t quite fill the faults perfectly in one application and sanding. In fact, we believe 2-3 is more likely the number of “coats” that will be needed, if perfection is your dream. There is a point at which the spray primer you use next should effectively hide any remaining “imperfections”, but we think you will find this is still at least two applications of the paste.
Wet sanding should be no problem as well, once the paste has dried. Wet sanding at extremely high grit numbers will get you closer to that lofty goal of perfection, at a much larger cost of time. We decided against using anything higher than 400 grit dry sanding, since most modelers will have a bit of 400 around. We believe this leads to a reasonable balance of work versus reward for most rockets. However, for those extreme mirror-finish chrome style nosecones, you will want to do everything you can, which includes many feathered applications of Testors Dimensional Craft Paste, “The Bondo of Nosecones”.
SUMMARY: While perfecting cast marks left on a nosecone is definitely optional work for High Power Rocketry, Dimensional Craft Paste fills the need beautifully. It adds a small amount of not-so-difficult work, requires very few tools, is extremely cost effective and long-lasting, at the expense of adding a few extra overnight drying times to your rocket building schedule.
