Melted sprue in gap-filling.

[automaton]

I'm always up for stealing new techniques, and I'm gonna give this a go. Have to pick up some turps at the hardware store first, though.

 

Regards;

 

Automaton

[Cat_baloo]

Heeey, go for it, Auto-Man. I've lost count of the ideas 'stolen' from modellers.

Rest assured, you're not 'stealing' anything new. As Solomon said, there's nothing new under the Sun.

And nothing I do, or have done, is original. I'm merely one of the few that's "put in on paper" if you will.

 

It's only contentment that others may benefit from lessons learned.

 

"Working hard means learning from your mistakes. Working smart means learning from others' mistakes."

 

Kind regards

 

Ros

[Derek B]

Hello Ross,

 

I sorta came this way after a nudge from Brian. Very cool explination and investigation into the properties of the turps/polystyrene mixture...Looks like I need to give this a go!

 

I suppose that this serendipitious way of discovering things is very rewarding...As I found out on the decals on my foiled kit - the clear decal carrier film became affected with marks, so I used white spirit to clean it. This effectively disolved and removed the carrier film, but left the decal design firmly attached to the foil (I had used Micro solvents to bed the decals down). So, apart from some very minor paint touch-up work, I now had decals on a foiled NMF aircraft that looked like they had been painted on and no visible decal carrier film! (I still don't know if this works on all decals - these were Revell decals).

 

Cheers and thanks

 

Derek

Edited August 22, 2011 by Derek B

[LSP_Kevin]

I've been experimenting with this technique myself over the last couple of weeks, and it's definitely a useful addition to the filling arsenal (careful how you say that ). I've noticed though, that you can sand it back beautifully smooth and flush after 24 hours, but you can't scribe through it at that stage, as it's still too soft. I haven't quite yet worked out how long I need to leave it before it attains full hardness, this has caught me out a couple of times so far. It may in fact be due to me having used a lot of turps in my mix (way too much, really), so perhaps my mixture is too 'wet'.

 

Anyway, I'll have to mix up a proper batch (rather than just plopping a few bits of sprue into an old jar of dirty turps!) and see how it goes.

 

Kev

[Cat_baloo]

Enjoyed your wee anecdote, Derek. Good to know you read up.

Ain't that the truth about serendipity, though?

And not a bad tip to retain, either, on the topic of cleaning off decals.

It's such an empirical environment, isn't it? I've yet to see a concerted, one-stop article that might catalogue these very niggles suffered in the pursuit of a hassle-free build. Plenty of Tips fora out there but scattered to the winds, such is the diversity of the hobby.

 

Kevin, awesome to hear you're having some success. And in spite of my meandering writing.

To reiterate, if you're having a hard time with residual softness you only need let it dry another day or two, preferably two. I've given it a week to be sure.

The amount of turps shouldn't be a factor. As I've explained, the styrene merely absorbs as much as needed to reach a consistent goop. Once out of the liquid it'll evaporate about the same rate.

What say you toss a few chunks into solvent? Stuff dries much quicker.

 

Are you going to post on your final surface finish? Would be a blast to compare notes.

 

Here's to more happy bashing!

 

Regards

 

Ross

Edited March 5, 2011 by Cat_baloo

[automaton]

I've been experimenting with this technique myself over the last couple of weeks, and it's definitely a useful addition to the filling arsenal (careful how you say that ). I've noticed though, that you can sand it back beautifully smooth and flush after 24 hours, but you can't scribe through it at that stage, as it's still too soft. I haven't quite yet worked out how long I need to leave it before it attains full hardness, this has caught me out a couple of times so far. It may in fact be due to me having used a lot of turps in my mix (way too much, really), so perhaps my mixture is too 'wet'.

 

Anyway, I'll have to mix up a proper batch (rather than just plopping a few bits of sprue into an old jar of dirty turps!) and see how it goes.

 

Kev

 

 

I've been experimenting with it too, and my experience so far almost exactly parallels Kevin's (except I don't have to be as careful how I say "filling arsenal", as in the U.S. there's no "r" in the word).

 

I'll definitely be using this technique in the future, to what extent I don't know yet. I also have to experiment some more with its scribing qualities. Lots of useful stuff to learn on this site.

 

Regards;

 

Automaton

[Cat_baloo]

I've been pottering with sprue goo on various kits.

Thought these may be of interest, to show the effects from application of differing quantities. The presence of air pockets is noteworthy. I used sprue in AutoSol solvent.

 

The 1/72nd Airfix F-4B needs some minor mods to the tail profile. I gooped melted sprue on the inside, to offset any harsh removal. It slightly distorted the external surface, as would be expected. Stuck in the plugs Airfix kindly supplied, for 'moving tailplanes', and smeared sprue over the remaining gaps.

In the end I didn't need as much to backstop the tail and the air pockets in both patches are apparent.

 

 

 

For cleaner results I'll apply the sprue goo much thinner. On Monogram's F-80C, you can see the absence of air holes from the lighter coats.

 

Masked the trenches around the stbd gun door and filled with thin smears. Since I don't want to display the engine and have the rear sitting on its stand I attached the fuz sections into two halves. (The tricky bit was to tape front & rear sections to a glass sheet, then use a piece of stiff sponge to prop up the trailing edge to align the wing root joint.) With everything supported and constrained with tape it was a simple thing to wick thin glue around the outside join.

Once secured I dabbed melted sprue around the internal joint.

Attended the sink holes in front of the join while I had the jar open.

Black styrene was from the Airfix 1/24th Spit stand.

 

It was dry and firm after a day but I left it another day, to be safe. This is the state of play after carving away the excess with a blade. Once sanded out, polished and primed it'll give an excellent base to re-scribe the panel join.

 

Hopefully a close-up will show the relative lack of blemishes. The dimples appear far worse than they are.

 

 

More to follow when the joins on the F-80 are done.

 

HTH

 

Regards

 

Ross

[LSP_K2]

I've used melted sprue as a gap filler before; adding layers of putty on top of that.

Edited November 27, 2011 by Typhoonattack1

[D.B. Andrus]

Excellent tutorial, will try both turpentine methods and lacquer thinner. I've been dis-satisfied with re-scribing available fillers for years, this technique really shows promise. Thanks!

 

Cheers,

D.B.

[LSP_K2]

After grinding large bits of plastic, I gather the shavings and throw them in a box just for this purpose. Waste not, want not, as they say.

[Cat_baloo]

Long overdue, some pics of the final re-scribe on the 1/48th F-80C.

 

I sanded and polished for a decent shine, to accentuate the new lines.

 

Nose panels.

 

 

 

Fuselage join.

 

 

 

 

 

Come time for the NMF finish I very well might leave it polished, to enhance the end result.

Normally I give a light scuff with 800-grit sandpaper, to 'key' the surface.

 

I hope these are clear enough for drill purposes.

 

Cheers

 

Ross

[phoenix 54]

Cracking 'show and tell' Ross.

Just to add, any plastic residue you 'shave' off,

throw it back in the pot, it just adds to the 'gloop'!

 

Paul, trainee Yorkshireman.

you know, a Scot with the charity drained out!

[Cat_baloo]

Quick fix for dihedral on simple wings.

 

Needed a new prescription a while back and, while the AMS maintenance dose was low, out came the AMT DH4. (Anybody else spot that "AMS" and "AMT" are only one letter apart? There's a reason for that.)

 

Quick word on the kit. Dubious fuselage shape - shows the prototype's gunner cutout profile - and wrong wingtip profiles.

In a fit of enthusiasm I reckoned a DH9a conversion would be as much fun as rectifying it to a 'real' DH4.

 

Anyhoos, enough of the blather. Three-views revealed the kit wing's dihedral is about 1-2 deg shallow.

Pasted the frontal views to thin board for a quick jig.

 

 

Filed and sanded the wings, re-shaped tips and centre cut-out. Carefully aligned fuselage to draw a line on the wing close to the fuz. Cut 3/4 through the top with a razor saw. Taped either side and filled with sprue.

 

 

 

Before:

 

 

Strapped to the jig with rubber bands the wing easily bends to the improved dihedral.

 

 

After:

 

 

Hope this was helpful.

 

Regards

 

Ross

Edited August 20, 2012 by Cat_baloo