Author Topic: Scratchbuilt hull material  (Read 15782 times)

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des

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Re: Scratchbuilt hull material
« Reply #30 on: November 19, 2019, 16:38:21 »
More progress - I've got the upper bow cladding on.

The hull is sheathed with 1.5 mm styrene sheet, but I thought that I might have a problem bending this material to get the tight bend at the bottom of the piece.  Nevertheless I thought I'd have a try.  The result is as I thought - a total disaster.  So instead I layered it up using 3 layers of 0.5 mm sheet;  this has given an acceptable result, although I will need to fill teeth marks from clamps used while the cement was setting.

Des

des

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Re: Scratchbuilt hull material
« Reply #31 on: November 19, 2019, 16:44:02 »
One thing I've found with using styrene as a building material, and using sheet-on-frame construction, is that you can be as rough as guts in the construction of the framework, but the cladding will still take on smooth lines.

Also, you can be fairly rough with the cladding as well, with cleanup using a dremel sanding drum or a mini file;  or by using filler where the sheeting doesn't match up properly.

The photo below shows how I got my original Lines Plan wrong.  I didn't recognise the error on the Plan, nor when I assembled the framework, nor even when I added the cladding to the sides, undersides and transom.  It wasn't until I added the chine cladding that the error became apparent.  But - filler to the rescue.

Des.
« Last Edit: November 19, 2019, 17:08:00 by des »

sea monkey

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Re: Scratchbuilt hull material
« Reply #32 on: November 20, 2019, 11:25:05 »
That's every tidy. You're making the styrene bit look easy. Nice work.

des

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Re: Scratchbuilt hull material
« Reply #33 on: December 10, 2019, 17:13:22 »
The basic hull is now mostly complete - still no decks or running gear, and still to have anchor pockets cut in.  But the hull itself is done.  So, yes, it is feasible to build a hull using styrene with a frame and sheathing method.

The hull is quite rigid, and surprisingly strong, despite weighing in at only 910 grams - about 2 lbs.  So I am still on target for the hull with decks to be around 1 kg, and for the completed model (with battery, but without ballast) to be less than the calculated 4.7 kg total displacement.

Did I get the chines right for a Burness Corlett hull?  Not quite - but if I build another one I now know where to make the changes needed to get closer to that target.

« Last Edit: December 10, 2019, 17:15:11 by des »

des

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Re: Scratchbuilt hull material
« Reply #34 on: December 10, 2019, 17:17:44 »
More photos.

The hull has been sprayed with several coats of high-build automotive primer / putty to fill minor imperfections, and to highlight any that needed attention - and there were several.

The slots at the bow are simply locators so I can cut out the openings for the anchor pockets in the right places relative to the internal frames.
« Last Edit: December 10, 2019, 17:34:30 by des »

sea monkey

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Re: Scratchbuilt hull material
« Reply #35 on: December 14, 2019, 16:45:58 »
You made that look surprisingly easy.
I'm tempted to give it a go on my next hard chine hull.
What are you using to glue the 0.5mm layers together to get them so flat and bubble free?

des

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Re: Scratchbuilt hull material
« Reply #36 on: December 14, 2019, 17:05:33 »
Mostly I use a Tamiya super-fine, clear liquid styrene cement.  This is actually a solvent, so a thin layer of each piece "dissolves" and migrates into the adjacent piece, giving a weld joint which is claimed to be as strong as the parent material.  I use this when I am looking for a quick result.

When I want more working time I use a Humbrol liquid poly cement.  This works in a similar manner, but takes longer to go off.

For those layered pieces I used the Humbrol to fix the first layer to the framework.  I applied the glue to the frame edges, stringers, etc, then applied the sheet styrene and clamped it in place with about 10 - 12 mini spring clamps.  The result was rather bumpy as the thin sheet material was not stiff enough to take on a smooth shape.

The second layer was applied using the same Humbrol liquid poly, applied over the whole surface area of the first panel and spread around between the two layers.  The second layer took on a smoother finish, and the third better still.

There are some cavities between each layer, but these are minor.  In a couple of places I've drilled through the first layer and injected some of the Tamiya cement to get a better fix between panels, and then filled the holes.
« Last Edit: December 14, 2019, 17:08:21 by des »