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Author Topic: Need advice for plastic model cleanup  (Read 375 times)

Bedwyr

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Need advice for plastic model cleanup
« on: 07 July 2021, 14:38:42 »
I'm about to go review the camospecs video on youtube, but before I do that what suggestions do you all have for plastic model mold line and error cleanup?

My background:
- Very used to using files and occasional knives on the metal minis.
- Also used to dealing with the hard plastic and excellent quality of gunpla plastic. This means that I've gotten plastic distress marks down pretty good where there are runner/sprue marks (fingernail rubbing is almost magic).
- Gunpla also does an amazing job at getting mold lines right at the edges of parts.


What to do about the softer plastic here? I was doing some initial work with a Citadel metal edge scraper, but I think that's doing more damage than good. A hobby knife I can't seem to control well enough to cut off mold lines but not cut off chunks of mini. I presume that using a file is just too much for the soft plastic. And finally what to do about misaligned weapon barrels?

Again, I'm about to look at the video for clues, but any advice welcome.
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Charlemagne

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Re: Need advice for plastic model cleanup
« Reply #1 on: 11 July 2021, 13:22:09 »
When you say misaligned weapon barrels, do you bent, or do you mean the mold itself was misaligned? If it's just bent then a dip in hot water, bending it straight, then dipping it in cold water to set it could help.
If it's a barrel that is fairly thin, I on occasion have drilled down into it and slid a piece of metal wire into it, far enough down that doesn't easily show, and then bend the barrel, with the wore inside it acting as an armature to keep it in place.
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Bedwyr

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Re: Need advice for plastic model cleanup
« Reply #2 on: 11 July 2021, 13:39:56 »
It's actually offset through the diameter of the barrel. Unsure whether it's remotely fixable using green putty. Maybe...
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Kibutsu

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Re: Need advice for plastic model cleanup
« Reply #3 on: 11 July 2021, 19:31:42 »
Use your knife in a scraping motion rather than trying to cut. This is much more controllable. Use sandpaper and/or metal files to go lover the mold seam lines very gently, then apply a bit of liquid cement to help dissolve the little rough bits that get left behind. My go-to is Tamiya extra thin.

CranstonSnord

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Re: Need advice for plastic model cleanup
« Reply #4 on: 11 July 2021, 20:25:22 »
I usually use a sharp hobby knife to scrape plastic mold lines, with the blade at 90 degrees to the surface. Failing that, diamond files work pretty well for most plastics.

Elmoth

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Re: Need advice for plastic model cleanup
« Reply #5 on: 12 July 2021, 00:55:15 »
An altenrative are nail files. The one syou use in your nails, yeah. They are extra cheap (I got like 20 fot 1 euro) and their grain is very small  so they smmooth things well. They go well for soft plastic, not so much for harder surfaces where I use my steel files.

Try it. It is cheap and the most you will lose if you do jot like it os a dollar/euro

Bedwyr

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Re: Need advice for plastic model cleanup
« Reply #6 on: 12 July 2021, 11:49:23 »
I think I'm good for general plastic treatment and mold lines at this point. It's all about the gun barrels now. Two halves of the barrel are offset. So in general when you have a misaligned cast on plastic, what are your go-to tools for reconstructive surgery. Replace the piece with other bits? Carve back the damage and repair with green stuff? Some other solution? Without getting into the weeds on this particular model (I can take a picture for later), what are the tools in your toolbox for this sort of damage on this particular material?
Alas poor Photobucket. I knew him Horatio, a fellow of infinite jest, of most excellent fancy.

CranstonSnord

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Re: Need advice for plastic model cleanup
« Reply #7 on: 12 July 2021, 16:37:44 »
Personally, I would cut off the barrel and replace it with styrene tube, or some other kitbash. Alternatively, cut off the misaligned part and replace it with a similarly sized tube with a pin. Or, if it's a PPC, call it a snub nose?

Bedwyr

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Re: Need advice for plastic model cleanup
« Reply #8 on: 12 July 2021, 17:02:09 »
Personally, I would cut off the barrel and replace it with styrene tube, or some other kitbash. Alternatively, cut off the misaligned part and replace it with a similarly sized tube with a pin. Or, if it's a PPC, call it a snub nose?

IIRC it's the longest one on the new BMR sculpt.
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CVB

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Re: Need advice for plastic model cleanup
« Reply #9 on: 13 July 2021, 08:06:09 »
I think I'm good for general plastic treatment and mold lines at this point. It's all about the gun barrels now. Two halves of the barrel are offset. So in general when you have a misaligned cast on plastic, what are your go-to tools for reconstructive surgery. Replace the piece with other bits? Carve back the damage and repair with green stuff? Some other solution? Without getting into the weeds on this particular model (I can take a picture for later), what are the tools in your toolbox for this sort of damage on this particular material?

(Ship model builder background here)

I wouldn't even try to carve and use putty. Any detail on a misaligned barrel  will be destroyed by carving and filing anyway. A plain barrel can be much easier replaced by polystyrene rod or tubes.
Evergreen has a selection starting from 2.4mm diameter for tubes and from 0.5mm for rods. (Disclaimer: I have no connection with them except occasionally purchasing some of their product at my local hobby shop.)

These can also be combined, by sliding pieces of rod or small tubes into bigger tubes (The barrel of the Mobile Long Tom would be a candidate for that).

You can also do a web search for "brass barrel model", "turned brass model" and similar. There is a whole after market industry for plastic and resin model upgrades. Some of those guns are actually small models in their own right complete with photo etch parts.


This is a 20mm Vulcan M61 gun at 1/48 scale which would scale to a 120mm RAC at 1/285.
(Disclaimer: no connection at all, I just found, admired and linked the picture).

The ultimate in custom barrels is to find someone with a hobby lathe and have your own barrel made, [edit] or costom order one from a local machine shop (who might demand a technical drawing with measurement or even a CAD file). [/edit]

If there is some very special barrel (imagine an M1919 Browning with its cooling shroud, frex) as a last resort you can take two of those misaligned barrels, very carefully file/scratch off one half from each and glue the remains together in alignment. Warning: expect a high failure rate!
« Last Edit: 13 July 2021, 08:11:48 by CVB »
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