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Painting fins off the rocket: how to hold?

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neil_w

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I need to pre-paint a whole bunch of fins (total of 7 pieces if I count right) off the rocket. The fins are basswood and vary from fairly small (maybe 2 sq. in.) to fairly large (30-40 sq. in.). I've already filler/primered them. Now I need to paint (I'll be using Rusto 2x gloss black in this instance). I'm not exactly sure how to hold them. Obviously the root edges will be masked off.

When applying filler/primer, I usually just tape them down flat to cardboard and do one side at a time. However, that doesn't seem to be good for getting a good gloss finish, because of all sorts of overspray issues. Ideally I would like a way to do many of them (if not all) at once, although I'd be totally OK with doing one side at a time if it came to that.

I feel there should be an obvious answer to this but it's not coming to me. I've prepainted parts before, but never large parts or many of them at once. Suggestions?
 

rharshberger

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Glue a skewer to the root edge, tape root edge to allow gluing later, and paint. After painting stick skewer in a styrofoam block while paint dries. After paint is dry use a razor saw to remove skewer and touch up with a sanding block.


If the fins are thick enough you can drill a hole in the root edge to glue the skewer into and make it a bit stronger.
 

MikeyDSlagle

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If they are thick enough you can can stick thin wire or pins/needles up into the root cord and then stick them in a piece of styrofoam, polystyrene, whatever. Push them in with a thimble or pliers or something. Last time I did it I heard a pop and it was the sound of the wire going into my thumb, way in. Then the other pop as I took my head out of my .... :-/ LOL I used steel fishing leader - the Tooth Proof type stuff. That was with balsa, not sure how easy it will be with bass wood.

Or use small spring clamps to hold the root cord where it is masked. Paint it and then hang it up. I use these for everything. Should be available at just about any big box store.

https://www.walmart.com/ip/4-Pc-4-Spring-Clamps-15-Packs-Hobby-Craft-Tools/140453013

Or cut grooves in a piece of foam just deep enough for the root cord to slide in and wedge the fins in that.

Double sided tape works okay if you are careful not to blow the fins over with your paint but I've had better results with the other methods.
 

BlaineS

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Long time lurker, first time poster...

Here's what I did last night...I used a 2 x 4 with paint stirring sticks nailed into it. Lower fin portion that passes through BT and glues to motor mount is masked off since it has been sanded for "tooth" before being epoxied in place. The whole fin is then taped to "the stick" with masking tape to hold it in position during first coats. Secondly, I use "Trigger" clamps to attach the fin to the paint sticks for other paint work. They are masked off before painting to protect them. Lastly, a fin is held in position with a trigger clamp and a second trigger clamp holds the first trigger clamp in the oreintation need for the fin to be worked on. Hope this helps!!! Thanks!!! Blaine www.classicorbit.com

47.jpg


62.jpg


71.jpg


100_1874.jpg
 

neil_w

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Two useful details I should have stated up front:
1) the fins are 1/8" basswood. So they're pretty thin, no drilling into the edges.
2) None of these fins are TTW, so there are no tabs to clamp onto.

Glue a skewer to the root edge, tape root edge to allow gluing later, and paint. After painting stick skewer in a styrofoam block while paint dries. After paint is dry use a razor saw to remove skewer and touch up with a sanding block.
I think I'm probably leaning in this direction, although I've never done it before. I'll glue a skewer (or maybe a 1/8" square dowel) using just a drop or two of glue to the root edges, and use them as painting sticks. I guess I've been a bit nervous about gluing something "temporarily" to the fins, but if I don't use too much glue maybe it'll come apart later without too much problem. Is there any specific technique that will ensure it'll hold enough for painting purposes but come apart easily enough later?

If they are thick enough you can can stick thin wire or pins/needles up into the root cord and then stick them in a piece of styrofoam, polystyrene, whatever. Push them in with a thimble or pliers or something. Last time I did it I heard a pop and it was the sound of the wire going into my thumb, way in. Then the other pop as I took my head out of my .... :-/ LOL I used steel fishing leader - the Tooth Proof type stuff. That was with balsa, not sure how easy it will be with bass wood.
I don't know either, but fear of impaling myself does play a role here. :)

Long time lurker, first time poster...Here's what I did last night...I used a 2 x 4 with paint stirring sticks nailed into it. Lower fin portion that passes through BT and glues to motor mount is masked off since it has been sanded for "tooth" before being epoxied in place. The whole fin is then taped to "the stick" with masking tape to hold it in position during first coats. Secondly, I use "Trigger" clamps to attach the fin to the paint sticks for other paint work. They are masked off before painting to protect them. Lastly, a fin is held in position with a trigger clamp and a second trigger clamp holds the first trigger clamp in the oreintation need for the fin to be worked on. Hope this helps!!! Thanks!!! Blaine www.classicorbit.com
As mentioned above, I don't have any TTW tabs to hold onto in this case.... but I did want to mention that I'm also building one of the NASA Trajectors... please post some pics when you're done!
 

LW Bercini

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I have used the skewer method many many times. First I mask off the surfaces that will be glued later, then I CA a skewer to the masking tape. Prime or paint as usual, then stick skewer into styrofoam as rharshberger said. If the pieces are small, I can stick the skewers in a jar. After all the painting is done, pop the skewer off the tape and save it for another time.
 

neil_w

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I have used the skewer method many many times. First I mask off the surfaces that will be glued later, then I CA a skewer to the masking tape. Prime or paint as usual, then stick skewer into styrofoam as rharshberger said. If the pieces are small, I can stick the skewers in a jar. After all the painting is done, pop the skewer off the tape and save it for another time.
It didn't occur to me to glue the skewer the tape. I guess that would be an ideal solution if I make sure to use really good sticky masking tape, because I've definitely had some issues with the little 1/8" strips of blue tape not holding so well to the wood.

BTW, I don't even know what to say about your new avatar... :eyepop:
 

BlaineS

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Hey neil_w!

Sorry I wasn't more help but, I do understand your fin painting dilemma much better now! :) Love that you to are building a Trajector. As a BAR, mine is my RTF vehicle after a 30 year launch "hold"... the cause of the hold was determined to be... "Life got in the way"! :facepalm: IMO John Pursley did a great job on the NASA skin! Please go to the website in my signature as the build is being documented. As I have time, I will update my site. Good luck your build and please share pics also!
 

afadeev

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I don't know either, but fear of impaling myself does play a role here. :)
No need to impale yourself.
It helps if you impale the fin along the grain of the wood.
Watch the video below at 8:30 mark for a visual demonstration:
https://youtu.be/plnvslb1MN0?t=520

I haven't had much luck with tape adhering to narrow surface areas. Either because I'm clumsy, or that I move too fast, or that the tape is not strong enough, or all three.

YMMV,
a
 

TomSmith58

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I take it this is a kit with pre-cut fins? If you don't mind duplicating you can re-create the fins in basswood and design them with tabs on the root to be cut off later.
 

neil_w

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Nope, I cut them myself according to specifications, but the important thing is that they're already cut. :) In hindsight, leaving some tabs on them might have been nice, although the wood parts were extremely tightly laid out on the wood sheet to fit optimally; adding tabs would have completely screwed that up and probably doubled the amount of wood I would have needed.
 

BABAR

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Skewer/dowel, white or maybe wood glue, and regular masking tape may be the solution.

Glue the stick to the root of the fin, adding tape around the dowel which just cover the lateral margins of the base of the fin (I am thinking you need a small area maybe around 1/8" of unglued base for the fillet to attach.)

Combination of tape and glue should hold the fin securely.

Paint the fin

Remove the tape.

Either use a knife or a heat gun to loosen the glue and remove the stick.

You now have a base of glue on the root of the fin which can serve as part of a double glue joint.

You have a bare area at the base of the fin that allows for the fillet to bond to the fin instead of the paint.

Since I am assuming that you will need to paint over the fillet anyway, I don't know that you are losing much in having to paint over the bare 1/8" unpainted base margin.
 

BABAR

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Another option would be glue tabs on, use spring clips, and cut off or use heat gun to remove tabs. Again, leaves some glue behind which can help for attachement
 

Amsterdam

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On fins smaller than what you're painting I've just taped a strip of masking tape sticky side up on cardboard, pressed the root edge on and painted them.
 

mkadams001

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Use double stick tape. The masking tape should be fine. I am presuming that you are using rattle cans. Stick the tape to a board or cardboard, anything flat that the tape will stick to. Stick the root edge of the fins to the tape leaving enough space between them for spraying. You might have to do a little cleaning along the root edge when you remove them. There are a lot of good suggestions in this thread
 

neil_w

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I ended up going with two methods.

For most of the fins, I stuck them to a piece of wood on the root edge using masking tape, like so:
IMG_6201.jpg

After thinking about it I decided that because on the largest fins the root edge was very long, it would hold sufficiently. Indeed, although they did waggle around a bit they ultimately held ok.

For my one fin that didn’t have a root edge, I tried the “CA a dowel to the masking tape” approach and it worked great. Well, so far at least... hoping I don’t have any trouble getting it off later.
IMG_6200.jpg
 
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