Nose cone finishing...

Eugene down in Florida says he wants his rockets to look like the kit art.

Ditto - except I am tool challenged, and have nowhere near his craftsmanship. But, after some experimentation and trial and error, I am begininning to produce rockets that come close to looking decent.

However, finishing big balsa nose cones, such as the BNC-60AH, still gives me fits. I apply sanding sealer with a brush, and I'm cursed with a mottled appearance to the cone (bumps and depressions), requiring major sanding to get things straight again. This, of course, removes the sealer and puts me back at square zero. I have applied the sealer thin and thick, with the same results.

So what am I missing here?

I suppose it could be that I'm a BAR, and slow to learn new tricks. I just purchased some sealer from HobbyTown, and the kid behind the counter asked me what plane I was going to build. When I replied that I was using it to seal balsa fins and nose cones of rockets, he replied "Man, does that stuff work? I mean, I use thin CyA to coat my fins."

So good people, please give me a hand and share a tip or two, My Citation Patriot clone needs a nose

...And decals soon - but that's a job for Astronboy.

The sealer fills in the grain. So when you sand it down to where it looks like the sealer is all gone, some of the pores are filled in.

You just need to repeat the process several times and the cone will be smoother each time.

I use Minwax Polycrylic for this because it's a lot less smelly and the brush can be cleaned with soap and water.

It still takes 4 - 6 coats before it's sealed but I think that it leaves a harder surface than regular sanding sealer.

Just a personal preference.

Originally posted by SpaceGarbageMan
So what am I missing here?

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Try multiple coats, allowing to dry and sanding between each coat. Remember to keep the coats thin.

I like to coat the cone with wood glue. After it soaks in and dries one or 2 coats of filler finish the job. makes the cone a little tougher too

I use mostly balsa nose cone that I "obviously" make myself.

I use one nice thick healthy coat of straight, out of the bottle, slapped on with a brush, Elmer's white glue and let that dry overnight.

The next day I lightly sand with 220 grit to knock the bumps off.

The Elmer's glue brings the "nap" of the wood up.

Then one nice hefty coat of "Fill 'n Finish" and let that dry.

Sand smooth with 220 or 320 grit, then a coat of primer followed by more "Fill 'n Finish" if needed.

Then the color.

I have coated them with finishing epoxy and let it drip off. There is some very minor filling after this, but it usually taken care of by primer coats. This also gives the NC a hard shell.

Originally posted by BobH48
The sealer fills in the grain. So when you sand it down to where it looks like the sealer is all gone, some of the pores are filled in.

You just need to repeat the process several times and the cone will be smoother each time.

I use Minwax Polycrylic for this because it's a lot less smelly and the brush can be cleaned with soap and water.

It still takes 4 - 6 coats before it's sealed but I think that it leaves a harder surface than regular sanding sealer.

Just a personal preference.

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Bob's idea is good. I like Polycrylic. But mostly I use Deft spray lacquer sanding sealer. It goes on smooth, dries smoother, soaks in well (due to stinky stinky lots of light hydrocarbons; use only outside), and rarely requires more than 2 coats (sanding after each, 400 grit then 600 grit). It also strengthens and fills spirals on body tubes. It doesn't require that you sand off the glassine coat from body tubes, and still allows great adhesion of primer coat to itself. I also got a quart can of Deft and have dipped nose cones in it (soaked them, in fact) to try to get a better result. Wasn't worse, but wasn't better.

But, Polycrylic is harder. If you might have landings on rough ground, it might save your nose cone's surface. And not stinky. Geez Louise, that Deft is stinky.

Something to try...

Apply the sanding sealer with a brush as usual, but then sand it while it's still wet with 220 or so. The fine dust created by the sandpaper will fill the holes, pores, and whatnot, and it will stay there because of the sealer acting like glue. After it dries, sand it smooth and repeat. That should fill up the large defects you get on balsa end grain much faster than just the sealer's film.

I think the amount of work to "finish" a wood cone largely depends on how it was made.

Having received cones from BMS, Sandman, and in kits, I can provide a good example.

BMS cones aren't sanded on the lathe before being declared "finished" by the manufacturer. The BMS cones are obviously cut with machine tools and are a tad rough. They need some sanding with 320 grit (max) to smooth them out before any kind of filler or finisher is ever applied, or you're in for a real chore.

Sandman uses sandpaper to "finish" his cones while on the lathe. They only need very light sanding with 400 grit (minimum) if any sanding at all. Nice and smooth right out of the box.

I then seal with about 3 coats of sanding sealer. I use Folk Art brand aerosol sanding sealer, available from Michael's. Sand the sealer with 400 grit in between coats. Works great!!!!

My favorite is to use either lightweight spackling or other similar product like Elmer's Fill n' Finish. I rub it it as is with my fingers. Water based and very quick to dry. Two applications usually does it, followed by some sanding to bring things back to level. Then I shoot with a good, sandable primer.

How does polycrylic sand?

Also, careful with the lightweight spackle. I've had some brands work and others are horrible. Of course, I can't remember which is which, so I just go with the wood filler.

Originally posted by BobH48
The sealer fills in the grain. So when you sand it down to where it looks like the sealer is all gone, some of the pores are filled in.

You just need to repeat the process several times and the cone will be smoother each time.

I use Minwax Polycrylic for this because it's a lot less smelly and the brush can be cleaned with soap and water.

It still takes 4 - 6 coats before it's sealed but I think that it leaves a harder surface than regular sanding sealer.

Just a personal preference.

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So if you are using rattle-can spray paint like Krylon, what do you have to do to get paint to stick? And by the way how does it work on body tubes (spirals)?

Originally posted by KermieD

How does polycrylic sand?

Also, careful with the lightweight spackle. I've had some brands work and others are horrible. Of course, I can't remember which is which, so I just go with the wood filler

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Polycrylic sands about the same as regular sanding sealer... It's just a little harder and takes a little longer. It's marketed as an alternative to polyurethane as a wood finisher. It drys clear instead of yellow like the polyurethane.

I've used spackle and, after sanding, used Poylcrylic over it. It takes less coats that way.

Originally posted by Polaris

So if you are using rattle-can spray paint like Krylon, what do you have to do to get paint to stick? And by the way how does it work on body tubes (spirals)?

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You don't have to do anything to get the paint to stick. I've used the rattle-can paints with and without primer and it sticks just fine for me.

I haven't bothered with filling spirals on most of my rockets because I have been using up the big box of body tubes that I bought back in the 60's and 70's. They are very high quality and you have to look carefully to even find the spirals.

I have bought some body tubes recently and notice the gaps are quite visible. That said, I think you would need to fill the spirals with something else.

If I understand, you use 3 or 4 coats of polycrylic before painting.

So what do you use to sand polycrylic – between each coat and final? Or any other tips that you might have.

I usually lightly sand everthing first.

For fins, I brush on a coat on each side before going to the next one. By the time I'm done with the last one the first one has soaked it all up and I give the fins a second coat right away. I then let it dry and sand with 320 or 400 grit paper. I then brush another coat and sand between each coat until it's smooth.

For cones you will have to let it dry between coats and then sand. The last coat can be left unsanded and it will leave a hard shiny surface that feels almost like plastic.

Then just prime and paint the way you normally would.

Depending on how soft the wood is to begin with, you could be done in as few as 3 - 4 coats or as many as 6.

If you use a filler (spackle or "Fill 'n Finish") first, you can get away with fewer coats.

This is not to say that it's better than anyone else's technique but I don't like using the stinky stuff anymore and I like to be able to clean up the brushes with soap and water.

I was experimenting with finishing techniques for balsa nose cones this weekend.

I took the nose cone from My Semroc SLS Skyhook and carefully glued a 1/14" wood dowel into the base (it's realy hard to get it centered!).

I chucked that dowel into my lathe and filled the wood with Elmers wood filler (It's the white water based paste that comes in a tube.)

I did three coat BUT after each coat was applied I turned my lathe on at a fairly high speed (500 rpm) and burnished the filler into the balsa using a scrap piece of leather I had laying around.

The heat cured the filler really fast, like within seconds, and I sanded it smooth with 220 grit followed by 400 grit.

The surface was like smooth plastic!

Nice and hard to.

I then primed and painted it wet sanding with 600 grit between coats.

The wet sanding was done on the lathe at high speed (messy!). I covered the lathe with paper and painted the cone on the lathe but turning the part by hand to paint it.

Man, I hope the pic does it justice.

I'm real pleased!

my best experience ever with finishing NCs was with elmers
Fill N' F
I apply it just thin enough to cover but enough to sand off...usualy anywhere from 3-5 cm thick. mabey less?
Then sand with nothing bigger 400 grit. Or I sand out scratch marks all day..
Then I take #0000 finishing steel wool i found at lowes/home depot. And rub it down with that till it shines.
It literally SHINES!
paints like a charm.

-matt

This is the nose cone for my new Sprint III project. It's a bit shorter than the "scale" Sprint cone but the same basic shape.

About a 2.2:1 parabolic shape.

One coat of Elmer's filler and burnished in with leather at high speed on the lathe.

OOPS! forgot the pic!

Originally posted by moocrew
I apply it just thin enough to cover but enough to sand off...usualy anywhere from 3-5 cm thick. mabey less?...

-matt

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I'm sorry - did you say 3-5 CM thick? You mean like 1-2 inches?

oh,...no
more like 1/8 in..or 1/16th. about the thickness of a popsicle stick to be exact. works pretty well for me.