Scratch-Building for Resin Casting

[abledog]

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.

[Johnnycrash]

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.

[Andrew Gorman]

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

[abledog]

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.

[abledog]

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!

[gsb5w]

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.

[Johnnycrash]

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. Internal structure could help with that, or thicker plastic.

[abledog]

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.

[OdysseySlipways]

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

[OdysseySlipways]

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