Scratch-Building for Resin Casting

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abledog
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Scratch-Building for Resin Casting

Post by abledog » Thu May 19, 2016 6:38 pm

Hi Guys.

I'm currently scratch building a ship I designed, so that I would be able to cast it in resin. I'm building it in a way that I can cast it with a hollow hull.

My main concern is that the sheet plastic I'm using is a bit on the thin side. How thin do you think I can get away with, so that the resin isn't too brittle?

Thanks. :)
Able D.

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Re: Scratch-Building for Resin Casting

Post by Johnnycrash » Thu May 19, 2016 7:02 pm

abledog wrote:My main concern is that the sheet plastic I'm using is a bit on the thin side. How thin do you think I can get away with, so that the resin isn't too brittle?
Many factors: Size, configuration, geometry, parts assembly needs...

Smaller parts can be thinner, and larger parts should be thicker.
John Fleming
I know that's not what the instructions say, but the kit's wrong anyway.

Andrew Gorman
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Post by Andrew Gorman » Thu May 19, 2016 7:35 pm

Before you mold it, thicken up the master on the inside.

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Post by abledog » Thu May 19, 2016 8:06 pm

Thanks guys! As I thought about it, I'm early enough on the project that it's worth it to recut the parts I have in a thicker plastic.

Originally I was thinking of thickening them up on the inside, but I thought it'd be better to save myself some effort by getting the best start that I can. :)
Able D.

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Post by abledog » Tue Jan 31, 2017 5:37 pm

I've added some plastic to my shapes & I noticed that I must've done something a bit wrong.. there is a slight 'bow' to the shape, it should be flat).

I'm guessing it has to do with how I applied the glue, (it's Ambroid-pro weld).

Should I use a thicker cement that I can spread evenly, or something else?

Thanks guys!
Able D.

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Post by gsb5w » Tue Jan 31, 2017 6:10 pm

It sound like the fit of your part is in a bind. That might be causing the bow.

I Never had a problem with the glue you mentioned bowing parts.

Melt plastic together on the other hand, yes. That's a good thing.
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Post by Johnnycrash » Tue Jan 31, 2017 6:51 pm

abledog wrote:Should I use a thicker cement that I can spread evenly, or something else?
Thin cement/glue is better overall.

Without seeing the part, it's hard to tell. It might be keeping it a secret, that's fine. If you could show a pic, might be able to tell you more.

Sometimes, with slight extra pressure, flat planes are no longer... Well, flat. :D Internal structure could help with that, or thicker plastic.
John Fleming
I know that's not what the instructions say, but the kit's wrong anyway.

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Post by abledog » Wed Feb 01, 2017 12:56 am

In looking at it again, I can see that there are pockets where there is no glue, so that the parts are just not effected. I think I did a poor job of distributing the glue properly.

I'm going to try it again with new parts. I'll also sandwich the parts between some thick books for a day, or so. ;)
Able D.

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Post by OdysseySlipways » Sat Feb 04, 2017 1:12 am

i use that Plastruc liquid cement but i use a fine paintbrush to do so.

when i glue parts together, i like to give the surfaces a light sanding (fine wet/dry sandpaper) and then put the parts together and then touch the brush along the edges. this will give you a much cleaner glue seam vs using that clumsy brush in the cap they give you.

the sanding will have scratch the surface and allow the glue to get sucked between the parts better as the scratches will cause a capillary action drawing the glue in for a complete surface bond
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Post by OdysseySlipways » Sat Feb 04, 2017 1:16 am

would you be willing to show up what your mastering? we might have some other ideas that may help you in your build
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