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Tips & Tricks
Ask about and post about tips and tricks you use while modelling.
Seam Therapy with CA & Fuselage Sanding?
ebergerud
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California, United States
Joined: July 15, 2010
KitMaker: 296 posts
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Posted: Wednesday, February 27, 2019 - 12:07 PM UTC
There's an interesting tip in the current article of Finescale - check the Corsair build. For seams the author suggests filing a bit off the fuselage sides (didn't specifiy one side or both) and create a kind of "V" when put together. Then, run some CA "Kicker" down the "V" when assembling the halves. Follow that with CA on a needle - enough to fill the trough created by the first step. Sand the CA within a few minutes before it goes rock hard.

I've never tried this. I'd heard of people doing the "V" filing and then filling it with Aves Apoxie Sculpt, but never CA. Actually it does sound interesting. Anyone out there used this technique? One trouble is that it would take a kit assembly to try it out - nice to have some input first.

Eric
RobinNilsson
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Stockholm, Sweden
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Posted: Wednesday, February 27, 2019 - 10:43 PM UTC
Sounds like a lot of work in order to avoid doing the work needed to get reasonable seems from the start.
Feels like inventing a complicated solution for the wrong problem.
I would assemble with glue, or rather pure solvent. Let dry.
Check for gaps. Insert thin shims of styrene into the gaps, file/sand the edge of the strip to a knife shape if needed.
Add small amounts of solvent to soften the styrene shim and do the glueing. Slice of the styrene sticking up above the joint.
Check seam and add more styren shims if necessary.
This avoids getting CA on the surfaces at the sides of the seam and there is less work with sanding afterwards.
A dry strip of styrene can be adjusted and corrected until it fits without making a mess with CA (or putty). When everything fits it is time to "go for it" and add the solvent to bond the strip in place.

The solvent I use is ethyl acetate.
/ Robin
ebergerud
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California, United States
Joined: July 15, 2010
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Posted: Wednesday, February 27, 2019 - 11:26 PM UTC
Actually it doesn't sound like more effort than what you propose. But no matter - I'm getting some very good advice on what should be a simple issue but isn't. I've got a couple of cheapo kits - I'm going to try to the Finescale technique and I'll try yours too. I do a decent job with seams (especially with my Duplicolor Primer which is sandable and fillable - actually true) but I'd sure like something closer to perfect. Thanks much.
RobinNilsson
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Posted: Thursday, February 28, 2019 - 02:52 AM UTC
A report of those comparison trials would be interesting
The problem I had with fillers like CA + kicker or any type of putty is that I had problems getting rid of the edges that formed. With styrene I can sand the edge to invisible since it is a single material instead of one material on top of another.

A variant or combination is to use CA to glue the styrene strip in place.
Capillary action will cause the CA to form a fillet between the edge of the kit part and the styrene strip.
It also allows you to use the styrene strip as a "landing zone" for the CA which makes it easier to avoid spilling over onto the kit part on the other side of the glue joint.
Inserting CA into a groove can allow the CA to flow out over the edges of the groove
Kevlar06
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Joined: March 15, 2009
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Posted: Thursday, February 28, 2019 - 05:19 AM UTC
I've never had any luck with CA as a filler. Usually, it hardens too quickly to do long fill jobs, and when it hardens, it's density is different than the surrounding plastic. I can sand all day, and it will just wear away the plastic before the CA, leaving an unsightly CA bulge. I've tried mixing baking powder and even flour into the gap with the CA, and nothing changes. I much prefer the method Robin uses, filling small gaps with styrene, or the "squeeze method" using liquid cement in the gap and squeezing parts together to get a "bead" of softened plastic, which can easily be sanded. I do have another method involving CA that I use for large gaps. If I have a very large gap or dimple, I fill it with putty (my favorite is red Bondo, followed by Tamiya white or gray). After smoothing the putty, then allowing it to dry for 24 hours, I lightly sand to shape. Then, after cleaning the area with some alcohol, I spread on a light coat of thin CA over the putty (generally, I use the tip of my index finger to do this very quickly-- just using a small drop of CA, but I have also used a polished wood dowel, shaped on the ends -- one round, the other flat), and continue to sand/buff after the CA dries (about 10 minutes). This gives a hard "shell" to the putty which blends it into the surrounding plastic, so when it's primed, it has a uniformly smooth surface.
VR, Russ