Wednesday, December 29, 2010
U.S.S. Atlantis - Step 8.5 (part 2), Preping the balsa parts for a smooth paint finish
Above you see the results of the first step which is 2 liberal coats of of the Balsa Fillercoat Primer. It leaves a very smooth "velvety" finish on the wood, sealing the finer grain but not doing much to fill the larger grain lines.
Next we apply 2-4 coats of good ol' sanding sealer, sanding between each coat until when held up to the light, you can no longer see any significant grain.
OK, the messy, tedious part is over. Now we want to prep the balsa main body tube for the primer coat. As you can see in the above pictures we want to mask the edges of the balsa pieces that will be a glueing surface. If we don't do this, the primer coat will prevent a strong glue joint between the balsa piece and the paper body tube.
Then we mask off the main body tube in a similar way using the lines we marked in step 6. Only mask off the length of each particular joint. This may seem like strong joints are one of the keys to clean liftoffs and damage free landings.
Finally, mask off the rear of the engine mount to keep it from getting primer and paint inside the mount which would cause the motors fit to be too tight.
U.S.S. Atlantis - Step 8.5 (part 1), Finishing Materials
Back in the good ol' days there used to exist a product called "Hobby Poxy Stuff" (thanks for the picture Jeff!) which was a thick brown goop that could fill even the most pourous of balsa grains in one thick coat.
I'm sure it was loaded with harsh chemicals and various carcinagens and stuff that makes the greenie weenie crowd cringe in fear...which I'm sure is why it was discontinued, but it worked great. It made filling balsa a breeze, and I really miss it!
So now, in the spirit of the 70's from whence this kit came, we are going back to tried and true "sanding sealer"... yes that smelly glue like substance that would fill the grain in a balsa fin in a mere 6 -8 coats. In an attempt to get that number down a bit, I'm going to try something new (at least new to me) called "Balsa Fillercoat Primer" (shown on the left in the picture below) as a first step.
Then we will follow that up with the sanding sealer for as many coats as it will take to obtain a smooth, grain free finish.
The last part of our process will be the liberal application of a thick sandable primer. I get mine at Ace Hardware but any thick flat grey primer will do the trick. This is the only treatment the body tubes will get to fill the spiral seems so we will most likely apply more coats to the body and engine tubes than we do to the balsa pieces.
Sunday, December 26, 2010
U.S.S. Atlantis - Step 8, Assembling the Main Deck
To protect my work mat and also to ensure we don't accidently glue anything to the workbench, I'm going to use wax paper as it states in the instructions. Some people use celophane wrap but wax paper is much easier to work with as it doesn't try to stick to itself.
So we lay out all of our pieces as shown above and make a small pencil mark 5 1/2 inches from the joint line between the forward and rear main deck pieces for the little piece that sticks out.
Once again, I prefer to use 2 part epoxy for this step though I know many modelers prefer to use cyanacrylate glue for balsa to balsa joints. I have nothing against CA glue, I just prefer the compromise between strength, fast (though not instant) set time, and strength that the epoxy affords.
When everything is glued, I fold the wax paper over the top of the assembled main deck and sandwhich the freshly glued parts in-between.
Then place a book or some other heavy object on top the wax paper to ensure that the entire assembly stays perfectly flat while the epoxy cures.
And now we have an assembled main deck, perfectly flat and as strong as if it were cut from a single piece of balsa. Our next step is one that is not in the instructions (so I will call it step 8.5). It involves sealing and priming all of the wood pieces that came with the kit so that when painted, they won't look like balsa wood. It is the most time consuming part of most simple rockets and my least favorite, but it's got to be done.
U.S.S. Atlantis - Step 7, Punching out the balsa pieces
I skipped the sanding in this step due to the fact that step 8.5 will be all about finishing. I simply gathered all the balsa parts and arranged them to make sure I wasn't missing any. After all its a very old kit thats been through alot of "moves".
Yep, looks like they're all there! Next up, assembling the main deck!
Saturday, December 25, 2010
U.S.S. Atlantis - Step 6, Marking the body tube
I do this a bit differently than the instructions describe (I know, big suprise there)... First I make a photocopy of the marking guide to transfer it onto thinner paper. You'll find it much easier to align it and get it taped on tightly than the thicker cardstock one that comes in the kit.
The other thing is that I prefer to use a doorjam rather than a ruler to make the lines on the tube. I suppose either works, but I learned this trick when I was a kid and it's always seemed easier to me than trying to get a ruler to lay flat on a round tube with one hand and mark the lines with the other.
Ok, not much else to say here other than make sure your lines are straight and parallel along the length of the body tube. Next up, balsa prep.... Ooooooh fun!
Monday, December 20, 2010
U.S.S. Atlantis - Step 5, Engine Mount Installation
O.K. so step 5 of our U.S.S. Atlantis build has us securing the engine mount into the main body tube:
We will be making two slight improvements to the kit design here; one structural and one cosmetic. The first modification (the structural one) will be the insertion of an additional block above the engine mount assembly that will help distribute any liftoff forces back through the main body tube:
When gluing engine mounts in place, I use a stick with a mark on it to allow me to apply glue at the correct distance in from the rear of the tube.
The second improvement will be to use the unused paper cardstock adapter ring from the engine mount assembly to dress up the back end of the main body tube:
That's it for this step... stay tuned for step 6.