Thursday 20 January 2011

Making Me Dee-Zee

This is one of those little jobs I’ve been saving for a rainy day. Or, to be more accurate, a day when you can’t make progress on your existing projects because you’re still waiting for bits you’ve ordered to arrive.

I’ve always planned to build some DZ wagons for the Bron Hebog fleet but since knocking out four for a client I’ve been struggling with the prospect of taking on such a repetitive job again.

The tricky bit on these wagons, you see, is the sunken panels on the drop down doors. On the batch produced last year I made them by scraping away at styrene with the tip of the scalpel. It was very effective but also very boring.

There are 2 panels on each door. 6 doors on each wagon, and 4 wagons in all. That’s 48 panels to be scraped out. So you’ll maybe understand why I haven’t been in a hurry to put myself through that again.

What if there was a way of mass producing them, though?

Etched brass would be the obvious way, but how to get those sunken panels looking right? As far as I understand the process you wouldn’t be able to etch a soft, rounded recess like those on the DZ’s. And I’m not sure how well it would work to try and press them into brass by hand. Would you be able to make them regular enough?

So instead I’m considering trying my hand at resin casting (or perhaps sub-contracting that out to an expert) and today I had a go at making a master.

I have posted before about the peculiar properties of styrene as a modelling material, and in particular its determination to bend like a banana, especially where thin pieces are laminated like the DZ doors would need to be. Not necessarily a problem if I was making the mould right away but it will most probably be a number of weeks, if not months, before I do that and I really don’t have much confidence my styrene styrene master will still be the same shape!

What if the master was half styrene, half brass? Now that wouldn’t bend, would it? So that’s what I’ve been trying today, with uppers layers of 0.15” styrene bonded onto a 0.10 sheet of brass beneath.



The other issue was how to make the sunken panels? This time I’ve tried out a different method. Instead of shaving away styrene I’ve used model filler to make the transition between the layers and I think it works just as well.



I know it looks a bit rough, but the photo’s been cropped and enlarged severely, so what you’re seeing is many times bigger than reality. That’s my excuse, anyway.

2 comments:

  1. Why not mould it in plastic? You could make a mold, place a piece of plasticard on top, heat up untill it is plexible then either place the other 'half' of the mould over the first and clap together. Or you could place a bag of flour or sand on top.
    Hope this helps
    Huw Jones

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  2. Or could you try making a mould tool and pressing them out of takeaway-tray foil? Not sure how fragile the end result would be though.

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