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Problems with build - need some help
communityguy
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Posted: Monday, June 11, 2012 - 08:12 AM UTC
Halp!

Another (yes another) newbie question...

After spraying a primer coat on my first build back in the game after years away, I've encountered three problems I'd like to figure out how to adress.

1. Even after puttying over the ejector pin holes on the inside of the Tamiya Opel Blitz bed panels, they still seemed to have shown up. Not as much as you might see in this picture vs. if they'd been untreated, but of course, my desire would have been to have had no showing at all. You can see what I mean in the green outlined box.

You can also see from this photo that the red box shows pins that I wasn't sure how to even get to, given the tight quarters. Any ideas on how you would have sanded and or puttied them? I used Squadron white putty straight from the tube.



2. When I was gluing the hood together, I apparently put too much liquid cement on and it ran between the grooves and made a really rough texture down the separation line. As you can see, the paint (and my efforts at sanding) covered up that ugliness a bit, but how can I:

a) Avoid this problem in the future, other than trying to better control the flow of cement (which seems like a minor part of the solution)

b) fix it after the fact?



3. As you can sorta see in this photo, there's some ugly part alignment between the grill piece and the hood pieces. What happened? It seemed OK when I was building, but after painting, it looks really ugly. I'm pretty sure that I didn't spray more/less paint in any particular spot that would have caused filling.

3b. Is there a way to fix this without having to fill the entire thing and scribe a line back in after that?



Thanks!!
russamotto
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Posted: Monday, June 11, 2012 - 01:25 PM UTC
With the disclaimer that I am no expert, here are my suggestions. For the first issue, go ahead and fill the ejector pin marks again. Use a sanding block for the holes out farther. You could add a couple of drops of Mr. Surfacer or similar product for the two pin marks near the corner, and use a sharp blade to carefully plane them level. A narrow, flexible sanding stick might also work.

For the second problem, I have applied the extra thin cement on both parts before joining, and also added the glue along the ends rather than down the center joint.

For the third problem with the fit of the parts, I have sanded things to make them as even as possible if it was way off, or used some card stock as filler. Hopefully, others will have better tips.
retiredyank
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Posted: Monday, June 11, 2012 - 01:53 PM UTC
I use a piece of music wire to apply cement. I always use the minimal amount of glue. To remove the glue, use some fine grit sand paper.
I agree with Russ on fixing the ugly separation between the grill and hood.
You can try white glue to fill the injector pin marks.
SSGToms
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Posted: Monday, June 11, 2012 - 02:07 PM UTC
Problem 1 - Fill the ejector pin marks again. For the ones in the corner, apply the putty with a micro screwdriver or square toothpick cut to the square section. Plane them down with a #11 blade. Sand them with a piece of sandpaper wrapped around the edge of a piece of .040 or .050 plastic card stock.

Problem 2 - You can smooth out the seam by carefully scribing it with the back of a #11 blade, or better, a dental tool or seam scriber.

Problem 3 - If you don't want to fill the gaps (which is what I would do) then get a seam scriber and scribe the rest of the seam to match the gap. The hood panels fold up and over from the side and do not fit tightly on the real truck.
Spiderfrommars
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Posted: Monday, June 11, 2012 - 08:16 PM UTC
1)

Common putties (as Tamiya or Squadron or Mr surfacer) shrink after they are dried. The solution is applying another thin coat of putty then, once it's cured, sand it down or smooth it passing on the filling a cotton swab damp with Tamiya lacquer thinner (That can save your panel lines). Don't be tempted to put a thick coat of putty at once. A large amount of it can warp the plastic parts.

2)

The better way to prevent this kind of problems, is avoid gluing the panel lines. You should have put the glue on the sides rather than pass the brush between the grooves.
The solution is, smoothing down the rough surface using a steel wool, then re engraving the line using a scriber.



Of course, to avoid huge mess, the glue has to be WELL CURED.

3)

In this case you don't have to fill the gaps, you have just to re-engrave the seam. Otherwise if you had to fill a gap before an engraving job, you wouldn't use the common putty because it would be too brittle. In that case have to use the CA glue as a putty.

Just my opinion anyway
communityguy
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Posted: Tuesday, June 12, 2012 - 02:38 AM UTC
Thanks for the feedback!

One part I didn't quite follow:


Quoted Text


Common putties (as Tamiya or Squadron or Mr surfacer) shrink after they are dried. The solution is applying another thin coat of putty then, once it's cured, sand it down or smooth it passing on the filling a cotton swab damp with Tamiya lacquer thinner (That can save your panel lines).


So are you suggesting:

1. Apply a normal coat of putty, sand down to flat
2. Apply a another thin coat of putty (but not THINNED putty, just not much straight-from-tube putty?)
3. Sand like normal
4. Pass a swab of thinner across the area to remove gunk from the panel lines?

??

Thanks!
CMOT
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ARMORAMA
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Posted: Tuesday, June 12, 2012 - 02:56 AM UTC
Another method you may like to experiment with to fill ejector pin depressions is is to cut circles from the required thickness of plasticard and glue them in the depressions, this will of course still need a small amount of filler but takes away the problem of shrinkage.
communityguy
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Posted: Tuesday, June 12, 2012 - 03:06 AM UTC

Quoted Text

Another method you may like to experiment with to fill ejector pin depressions is is to cut circles from the required thickness of plasticard and glue them in the depressions, this will of course still need a small amount of filler but takes away the problem of shrinkage.


I've heard that before, but I've not really understood how that would work in practice. Maybe it's just because the Tamiya kits don't have really deep depressions that it doesn't make sense how that would work?
Spiderfrommars
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Posted: Tuesday, June 12, 2012 - 04:51 AM UTC

Quoted Text

Thanks for the feedback!

One part I didn't quite follow:


Quoted Text


Common putties (as Tamiya or Squadron or Mr surfacer) shrink after they are dried. The solution is applying another thin coat of putty then, once it's cured, sand it down or smooth it passing on the filling a cotton swab damp with Tamiya lacquer thinner (That can save your panel lines).


So are you suggesting:

1. Apply a normal coat of putty, sand down to flat
2. Apply a another thin coat of putty (but not THINNED putty, just not much straight-from-tube putty?)
3. Sand like normal
4. Pass a swab of thinner across the area to remove gunk from the panel lines?

??

Thanks!


Since your ejector pin marks are stiil visible, I advise you to apply another thin layer of putty on them. The putty can be diluted or straight from the tube, it doesn't matter in this case, you have just to avoid appliying too much of it.
Once the putty is well cured, you can sand it down using sandpaper OR a cotton swab damp with lacquer thinner.

So the stepas are:

1 apply another thin coat of putty
2 wait until is cured
3 sand it down with sandpaper or a cotton swab damp with some Tamiya lacquer thinner (yellow top) or "Gunze Mr color thinner"

Don't use the common lacquer thinner that you can find in hardware store! it damages plastic.

If in the end you pin ejector marks are still visible...you'll have to repeat the process (I know, is quite boring, but that's the only way)

I hope that is quite clear now, I aplogize for not being clear enough in my first comment

Cheers
communityguy
#280
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Posted: Tuesday, June 12, 2012 - 07:52 AM UTC
Ah, I see what you're saying, thanks!

So basically is the idea of using the thinner + swab that it just "wipes away" small amounts of putty at a time? I guess part of what I'm not understanding is how that would work vs. sanding. Sanding seems pretty straightforward in what's happening: you're reducing the higher material to the level of the lower material in a single, flat plane.

With the swab, it sounds like you're doing the same, just in as a less "flat" plane?

Also - what would you suggest thinning the Squadron white putty with?

Thanks for the help!
Spiderfrommars
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Posted: Tuesday, June 12, 2012 - 08:31 AM UTC

Quoted Text

Ah, I see what you're saying, thanks!

So basically is the idea of using the thinner + swab that it just "wipes away" small amounts of putty at a time? I guess part of what I'm not understanding is how that would work vs. sanding. Sanding seems pretty straightforward in what's happening: you're reducing the higher material to the level of the lower material in a single, flat plane.

With the swab, it sounds like you're doing the same, just in as a less "flat" plane?

Also - what would you suggest thinning the Squadron white putty with?

Thanks for the help!

The main problem in "sandpaper method" is that you delete the details or risk creating dents or depressions on your surfaces. The "cotton swab method" is less fast (sometime you have to add more putty and repeat the process again), but allows you to save panel lines and details, because the thinner is far less agressive with plastic. That's one of the reason why is one of the favorite method adopted by aircraft modellers who have lots of engraved lines,rivets and details on their models.

Here a tutorial about

http://p47.kitmaker.net/forums/98974&page=1

Of course, it doesn't matter if the thread is about an aircraft build, it works also for AFV models

As the thread sais, to dilute the putty you can use a polish remover. I've never used Squadron white putty, anyway I think that is likely to have the same composition of Tamiya putty so you can thin it with the same type of solvent.

I hope it is useful for you

cheers
vonHengest
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Posted: Thursday, June 14, 2012 - 01:46 PM UTC
Both the white and green Squadron putty work well with acetone. I still prefer using the Tamiya putty, but I am pleased with all three.
Spiderfrommars
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Posted: Thursday, June 14, 2012 - 08:23 PM UTC

Quoted Text

Both the white and green Squadron putty work well with acetone. I still prefer using the Tamiya putty, but I am pleased with all three.


Hi Jeremy

Acetone is more aggressive with plastic than Tamiya lacquer thinner and nail remover. Some guy even use it as a subsitute of Tamiya thin glue
Anyway, it eveporate fast, so if it's used carefully, it won't create any problems

cheers
vonHengest
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Posted: Friday, June 15, 2012 - 12:43 PM UTC

Quoted Text


Quoted Text

Both the white and green Squadron putty work well with acetone. I still prefer using the Tamiya putty, but I am pleased with all three.


Hi Jeremy

Acetone is more aggressive with plastic than Tamiya lacquer thinner and nail remover. Some guy even use it as a subsitute of Tamiya thin glue
Anyway, it eveporate fast, so if it's used carefully, it won't create any problems

cheers


My apologies, I meant nail polish remover
Tankworks
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Posted: Wednesday, June 20, 2012 - 04:28 PM UTC
Sprue melted in a part jar of liquid glue makes the best filler, mix it until it is goopy. It is self-leveling and welds right in and it sets up to the same hardness as the plastic part and if you are careful there is a minimum of sanding to do.
Red4
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Posted: Monday, July 02, 2012 - 12:21 PM UTC
Your sink marks on the wood grain are easy to deal with. Simply fill them again with putty and block sand them. Block sanding will work better as you will have a level plane taking off the material. If you just use plain sand paper it will eventually start taking putty material from the low spot as you pass over it. If you lose the wood grain detail you can put it back on with a micro saw blade, scribing tool or the back of a #11 blade simply by dragging/scratching the surface again. As to the one in the corner, I would use the backside of a #11 blade and scrape it out. It is so tight I highly doubt it will be visible once the build is complete. However, you can rescribe the wood grain if you really wanted to. Hope this helps. "Q"
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