Photo etch on compound curve

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Malcolm
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Photo etch on compound curve

Post by Malcolm »

Hi there.
I've attached a picture of my partially completed tub for the Tamiya 1/12 Tyrrell 003.
Tyrrell.jpg
I'm using the SMS photo etch (large!) kit and the next bit is a couple of very thin pieces (one in the photo).

The place were these need to go is a complex curve and I'm trying to decide how best to glue them. The photoetch is very thin (0.1mm) and so is relatively easy to bend and it only takes about 16 fingers at once to hold it all into place!

I think it's going to be impossible to clamp it, so I was wondering about contact adhesive, but I have reservations since, in my experience, contact adhesive is on the thick side and I need a thin glue so that all the bits of the photo etch meet together.

So, does anyone have any experience with contact adhesive in this scenario. Of course, any other tips would be most appreciated.

Best wishes
Malcolm

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Malcolm
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Re: Photo etch on compound curve

Post by Malcolm »

PS, does anyone have any idea why I've got that ugly white space to the right of my picture?

It's a file that I've uploaded and there's no white to the right of my original picture.
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Re: Photo etch on compound curve

Post by Paul_OFarrell »

Hi Malcolm,

You could consider shaping the PE piece into the desired shape prior to gluing it in place.

I would take a casting of the concave area from the tub. Then grab a block of medium density wood and carve a wooden buck into the required concave shape using rounded chisels and riffler files, or even a motor tool fitted with a ball cutter - a cutting tool similar to a dental burr.

After the wooden buck is formed, heat the metal piece with an appropriate blow-torch to anneal the metal and soften it enough so that it can worked into the same shape as the carving in the wooden buck. You could also consider making a few basic tools for the reshaping purpose - a piece of rounded broom handle may work perfectly as a reshaping tool.

If you tried to glue the metal plate into position with an instant adhesive while the piece is flat, I would expect the metal to spring back into it's original shape, and therefore remove itself from its intended location.

Experiment first with a piece of aluminium from a soft drink can. This will help you get a feel for reshaping metal.

If the PE piece proves to be too difficult to form into the required shape, then perhaps the aluminium piece may be better suited to reshaping.


Or, failing all of the above, you could grab a sheet of Bare Metal Foil and line the entire tub surface with this material. BMF has several shades of metal finishes available, and you can always run a pencil eraser over the applied surface to remove some of the shine.


Let us know how you get on with this matter. I would be interested to see your results.

Cheers, Paul
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Re: Photo etch on compound curve

Post by jaydar »

The photoetch piece can be made more pliable by heating over a match. Don't overdo it. It is already thin and you can melt it.

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Re: Photo etch on compound curve

Post by dmandam »

Hi Malcolm,
As it happens I am cladding a monocoque with 0.2mm aluminium and 0.1mm litho plate at the moment.
3M Super 77 'Classic Spray Adhesive' is working for me.
Anneal the part (stainless will take some heat but be very careful if it is aluminium) and shape it with your fingers as much as you can then anneal again; you need it to be as soft as possible and shaping it will work harden it. A candle or low gas cooktop burner should do the trick but do avoid blow torches (!) and do a test with some surplus PE first.
Then a light pass with a can of 77, position and hold. The forces involved are small so little strips of tape around the edges will "clamp" it once it has gone off a bit; just leave it overnight to cure.
Good luck...
David M
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Re: Photo etch on compound curve

Post by smb »

Ditto on the 3M Super 77 glue.
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Re: Photo etch on compound curve

Post by mvc »

Hi,

In order to be able to clamp it, you could create a mold from milliput (or something similar).

Prepare a big lump of milliput, cover (part of) your model with cling film/plastic wrap to avoid contact, press the milliput against it and let it harden. When hardened, you have a perfect negative shape of that part of the tub. Use this piece to press your PE part in place.

Hope this helps,

Marcus
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Re: Photo etch on compound curve

Post by PeteJ »

One thing about the metal that SMS uses. If memory serves me, it is nickel silver or german silver which is a copper/nickel alloy so that it can be soldered. Perhaps Matthew will weigh in here and set us straight. If it is, then annealing it is a must. My work with this alloy is that it is very ridged in its as manufactured state. The good part is that after heat treating, although it will look terrible, polishing it back to its original finish is quite easy. A light sanding should do the job for a brushed finish. If you want a bright finish, then a Dremel with a cloth wheel and some jewelers rouge will do that.

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Re: Photo etch on compound curve

Post by stubeck »

I know this isn't what you truly intend to do, but could you use Alcad Aluminum for this? I had great success with my Lotus 79 with doing a base coat of gloss black and then doing a very light finish of Alcad II Aluminum to get a realistic finish.

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Re: Photo etch on compound curve

Post by dmandam »

If it is nickel or silver alloyed with copper then there is a risk of 'fire scale', i.e. where the copper comes to the surface and leaves a slightly darker patch. Try to anneal just once or twice using minimal heat. Some alloys are fine, others not so much: test first on some scrap and see what works best.
Sanding will remove fire scale but is a PITA on something so small and soft and can make for a different finish to the surrounding panels.
Working all the surfaces over with a scratch brush can disguise the fire scale and even out the finish.
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