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Tips & Tricks
Ask about and post about tips and tricks you use while modelling.
fixing bent barrels?
phil2015
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Illinois, United States
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Posted: Thursday, June 04, 2020 - 12:41 PM UTC
So I have this Zis-3 from Miniart and it happens that one half of the gun barrel is bent. (That's the only piece, I guess it might have been pressed against something else in the bag for a long time to have caused this).

Is there a reliable way to straighten such a thing? I've fixed warped ships hulls, but they are usually warped perpendicular to the flat waterline. This is warped not perpendicular to the flat half but parallel to it. Might produce a droopy barrel. I haven't tried glueing it to the other half which looks fine.
petbat
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Posted: Thursday, June 04, 2020 - 02:46 PM UTC
Heating in hot water then laying a book or something with enough weight to hold it against a flat surface my work. Not too heavy or it may flatten the part.

You may need to build a jig to try and hold it flat and straight. A flat metal plate and strong mini magnets might work.

Alternately, how about replacing it with a metal barrel like RB Models #35B93?

phil2015
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Posted: Friday, June 05, 2020 - 02:15 AM UTC
Thanks, Peter.

With a ship's hull i just clamp it to a metal bar and put it in hot but not too hot water. The advantage of that is that you don't have to touch any of the exterior surfaces of the hull. And, you're just trying to make it flat rather than flat and straight....

I imagine I'll end up with a metal barrel like that. They do look nice. As long as I have this bent thing though I should see if I can fix it - practice I guess...
phil2015
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Posted: Friday, June 05, 2020 - 05:12 AM UTC

Is that RB barrel in your picture in the mini-art Zis-3 kit? There's a place here that has it, says it's for an SU-76, so just trying to make sure it will fit my kit....
petbat
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Posted: Friday, June 05, 2020 - 08:42 AM UTC
Yes Phil. The Su 76 used the Zis 3. Checking the sprues of each kit, you can see the barrel and components were from the same master in each kit:


The instructions show same construction sequences for the same parts - Zis 3 kit left, Su 76 kit right:

phil2015
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Posted: Friday, June 05, 2020 - 09:43 AM UTC

Excellent, thanks! I think that's what I'll do!

I feel there is an SU-76 in my future soon, too! I'll prolly do the Tamiya kit though.
petbat
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Posted: Friday, June 05, 2020 - 12:31 PM UTC
Go the Tamiya one and you won't regret it. Miniart's is very nice, but you can't beat Tamiya for buildability.
Grauwolf
#084
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Posted: Friday, June 05, 2020 - 10:55 PM UTC
You can use your thumbs to apply opposite pressure along the
length of the the barrel till it straightens out and then glue
a length of brass tube on the inside groove before gluing the
two halves together.
Cheers,
phil2015
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Posted: Saturday, June 06, 2020 - 02:34 PM UTC

Interestingly enough, the gun barrel that is bent is the barrel for the Zis-2. I didn't realize you get both in the kits. Interesting to know....
RobinNilsson
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Posted: Saturday, June 06, 2020 - 10:05 PM UTC

Quoted Text


Interestingly enough, the gun barrel that is bent is the barrel for the Zis-2. I didn't realize you get both in the kits. Interesting to know....


Excellent! Problem solved ....
unless ....
you have started fancying that RB Models barrel
phil2015
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Posted: Sunday, June 07, 2020 - 12:46 AM UTC

Quoted Text


Quoted Text


Interestingly enough, the gun barrel that is bent is the barrel for the Zis-2. I didn't realize you get both in the kits. Interesting to know....


Excellent! Problem solved ....
unless ....
you have started fancying that RB Models barrel



I built the zis-3 barrel and I'll probably go ahead an get the metal barrel. It's a two part barrel that requires a lot of sanding. I won't know for sure until I get some paint on it but I imagine it will not look that round once I get there.

I will work on the zis-2 barrel though to try to get it straight. Sadly I don't see a zis-2 barrel with either RB or Aber.....
phil2015
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Posted: Sunday, June 07, 2020 - 11:52 AM UTC
Grauwolf's suggestion to use a piece of brass rod worked great! I did not have to heat it. I glued the brass rod into the groove using CA glue and then using plastic glue to glue the two halves together made it straight in every angle.

Sadly trimming the join on both barrels made them noticeably out of round. So, I'll be taking Peter's suggestion and doing the Zis-3 with the metal barrel.
Grauwolf
#084
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Posted: Monday, June 08, 2020 - 03:47 AM UTC
Phil.
If you build barrels that are split in two halves, you should
consider a seam scraper with various diameters.

You run this tool down the length of the barrel and being curved,
prevents the barrel from going flat when you scrape off at the seam
or joint.

Here is the tool I am talking about:

https://www.ebay.com/itm/Alexen-Model-Parting-Line-Scraper-Hand-Tool-for-Assembly-Model-Hobby-Kits/153464998028?hash=item23bb3a088c:g:5jgAAOSwivlcwrkg

Do a search, there are many vendors selling this item.

It is an excellent tool to have.
Works well on aircraft and ship models too.

Cheers,
phil2015
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Posted: Monday, June 08, 2020 - 05:32 AM UTC

Oh, that's awesome. When I started reading I thought, I have a seam scraper, how's that going to help? Then, when I looked at the picture, it's "Oh, I don't have a seam scraper like that!"