Scratchbuilding Idea - Scale Sheet Metal Work

I haven't seen this technique mentioned before, so pardon me folks if I'm re-inventing the wheel.

Power supply capacitors (those aluminum cylinders inside old TV's and radios) contain rolled up metal foil in a wide variety of textures and shades. The foil is made of aluminum, zinc, and various alloys - some shiny, some dull. Unpainted, it makes great stainless and plate steel, galvanized iron and aluminum, depending on the foil. Painted, it can be anything you can shape or emboss, the only limitation being that some priming is needed to overcome the porous nature of the metal.

Make sure the capacitor is discarged (short the terminals) if you don't want a nasty shock. If they're old they're probably dead, but do it anyway. It's a good habit. Now pry them apart from the bottom, avoiding damage to the containers (which make great oil storage tanks). Unwrap the foil carefully (the edges are sharp!) and separate it from the paper insulation. The paper is soaked in mineral oil. Discard it, then wash the foil in dishwashing liquid and roll onto dowel, pencils, etc. With the capacitors from a single dead TV, you'll have a substantial supply of scale sheet metal.

Some uses I've found in N-scale:

Corrugated siding. Here I simply emboss the foil using pieces from the Kibri Coal Loader as a pattern, then cut them to size. Good for that bashed up look. Poke it with a stick, tear a hole or two, add rust and serve!

Corrugated pipe loads and culverts. As above, then bend the piece around a knitting needle or dowel of appropriate diameter. Close the joint with ACC, and hide by facing inward, or downward as required.

Open top barrels. As above, but with only two or three embossed lines. Bottoms can be formed with a small punch. Closed top barrels can be made from dowel, with a bit of foil glued to the ends and filed flush, then wrapped with the embossed sides. Nice scale looking rims, if you go a little wide.

Lacing for truss bridges, using the paper doll approach. Added advantage of embossed rivets in the larger scales. Also good for fillet plates.

Coiled steel, and coilcar covers. Wrap the foil several times around a dowel, remove dowel, band with black hair or fine thread. The coils are very convincing, since they're real metal. You can also make unusual shaped covers that aren't commercially available. Just cut and bend like paper cut-outs in kids books (don't forget the tabs). You can dent these up nicely too.

Sides, roofs and ends. I used the drop-floor of a Dimi beet car, the sides of a Rapido hopper, and the drop-end of a Microtrains gondola as patterns for an Otis ballast car (embossed parts glued to styrene body - you could use filed down car bodies here too). I've also used foil to make replacement doors for chunky old Atlas cars, and the sides of a woodchip hopper as a pattern for 62' mill gondolas. Other parts can be made along the same lines.

Tip: Intalling grab irons on embossed car sides is much easier if you do it BEFORE you glue the sides to styrene! A small pin hole is all you need, then push the grab irons through. Score the styrene backing to accomodate the snipped or bent ends. Far easier than drilling holes! Don't use styrene cement to attach the embossed metal either, or you'll get warping, as I learned the hard way.

Tip: a sharp H or HB pencil makes a smooth embossing tool. Scrub the loose graphite off with a soapy toothbrush, then spray with primer.

These are just a few of the possibilities. I'm sure there are more. One of the nice things about this material is you can bash it up and it looks like real damage, such as warehouse doors hit by a forklift, or rock damage on mining structures. One project, as yet unstarted, is to emboss some gondola sides, then dent the hell out of them to simulate the damage you see in scrap service. Wrecked cars on the dead track are another possibility. A good place to display your first efforts .

Mac B. Vancouver BC

Reply to
polar bear
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polar bear spake thus:

Sounds like a kewl idea; however, on second thought, it occurs to me that there's a real risk of those old capacitors containing PCBs, which was used as dielectric material back in the bad old days. Wouldn't want to get that stuff on you. So I think I'll pass.

Reply to
David Nebenzahl

You have a very good point David.

I was under the impression that PCBs were only used in large industrial transformers and capacitors because of their resistance to heat, but on looking into it further, it turns out they were used just about everywhere, from fluorescent lights, to paint, to fire retardants, hydraulic fluids, electrical components, and a wide range of other devices. They were banned by an act of Congress in 1977, so I imagine anything made after that date is relatively safe, although it's probably better to just look for another source. Maybe a metal manufacturer or scrap dealer?

On the other hand, PCBs are everywhere in the environment, including the food we eat, and even in polar bears in the arctic, so you really can't get away from them. Like the commercial says... you're soaking in it.

Frankly, I'm more concerned about my years of exposure to lead, benzene and hydrocarbons than one exposure to a couple of old capacitors. I worked in the oil industry for ten years, back when that stuff was in the mix. Also carbon black and asbestos, since I worked in ship engine rooms for some of that time. And smoked cigarettes. Aaarrrgh! I'm doomed!

Come to think of it, working for a railroad probably isn't all that healthy either.

Point well taken though. Thanks for bringing it up.

Mac B.

Reply to
polar bear

polar bear spake thus:

You're quite welcome. I didn't intend to put a damper on your inventive use of indigenous raw materials for modeling, which is exactly what I like to do. And since you mentioned it, let me ask about one of the things you're modeling: corrugated metal. As we know, this material is one of the four or five essential elements for model railroad alchemy. Currently, the best stuff available is Campbell's storebought metal sheets. It's good stuff, but expensive.

I've been thinking about trying to make my own out of thick aluminum foil. The ultimate, of course, would be to have the proper machine: basically a better, finer version of those craft crimpers they sell to scrapbookers, with two ridged rollers. I wonder how much it would cost to have a machinist cobble something like this up.

The alternatives, like the one you use, seem to involve rubbing metal sheets against a pattern of some kind; one article I've seen suggested gluing down strands of spaghetti and using that as a form. What exactly is that Kibri model like--does it have ribs? Anyhow, it seems this method might work pretty well to create fairly funky metal, like you'd see on old, corroded structures, but probably not the nice new uniform look of the Campbell's material.

Reply to
David Nebenzahl

That's the rigid stuff, right? I bought some of that years ago when I worked in HO. I left it outside to rust naturally, which worked really well. The trick is to set it at an angle, so the rust streaks in the proper direction. You need lots of patience though, 'cos it takes about a

I've also seen little packages of individual corrugated sheets in n-scale which looks like the stuff I make. Way over-priced. You'd need hundreds of dollars to do a big coal loader or industrial plant. More suitable for sheds and pump houses. I didn't notice the brand name, but it's some cottage operation. Hope the guy isn't salvaging his foil from old capacitors...heheh.

Aluminum foil tears too easily and it's the wrong color. The stuff you find in capacitors is thicker, stretches to shape, and actually *looks* like sheet metal. To make a car side - for example a gondola - you cut an oversized square, wrap it around the shape you're copying, then press on it. That sets the basic form. Then you press a little harder with a pencil-end eraser, then emboss with a dull HB pencil, and finally a sharp (but not too sharp) HB. Takes a little practice, which is why I cracked wise about the dead track. Probably better to do a resin cast if you're making lots of them.

Remember, this is n-scale. I doubt you could do a ribbed car side in HO. Too deep. The metal will only stretch so far. That would be more of a bending operation - very fussy. You'd probably be better off using plastruct.

Well, you *could* just use the campbell sheets as a pattern. The pieces should come out nice and flat if you're careful. The foil is thin enough that overlapping the pieces isn't a problem. If you're using heavy aluminum foil, you'll probably want to glue it to a paper backing before cutting it up.

It's really not much effort to make. Cut the foil oversize, and bend the ends around your form to hold it in place. Or you could just tape it. Run the pencil down each groove, working from the middle out, then flip the piece over - that's the part that faces out. The sheets will come off your form with a curve, but that's easy to straighten. Light pressure with a paint roller or cardboard tube does the trick.

The Kibri N scale coal loader (B-7458) is an old kit. Not sure if they still make it. It has a tall framed coal tower, and a large sheet metal shed, but any styrene kit representing sheet metal would work.

I don't have a webpage to display the stuff, or a digital camera for that matter - spent all my money on trains - but I can assure you. it looks very nice.

Mac B.

Reply to
polar bear

I gave a lot of thought to this, and did some digging around on the web. This stuff is just too good to let go without a fight!

Turns out PCBs have been used in electronics since the 20's, and some, but not all capacitors used it as a dielectric. The oil-in-paper capacitors are indeed mineral oil, but what else is in there? Mineral oil by itself is a good dielectric, but I'm sure some of it was "enhanced" so there's really no way to tell.

I looked around for manufacturers, and sure enough there's plenty of metal foils of every possible description available. Trouble is, they only sell in industrial quantities. You *might* be able to scrounge scraps from a manufacturer, or even an end user (such as a capacitor maker ) but this seems kinda sketchy. I thought about scrap dealers, but any scrap foil would probably be pressed into bricks before it reached those guys.

There is another possibility though. High voltage capacitors are common in high end audio equipment such as PA systems. (these guys argue over which is the best capacitor the way we fight over switches vs turnouts) PCB's are NOT used in modern capacitors (post 1980), and the law says you must label them as such: "Does not contain PCBs"

So, any commercial audio electronics shop that deals in PA systems ought to be throwing out a fair number of dead, newer capacitors. Just so long as it says "Does Not Contain PCBs" on the casing, you should be safe. I'm going to call a few places next week and see if I'm right.

You know, I'm surprised this stuff isn't sold in sheets as a common hobby material. One place where it would really take off (no pun intended) is the model aircraft world. I've got a Nordstrom Viking seaplane kit that's going to get the treatment, if I ever find the time. Say.... I wonder if those radio controlled servos are adaptable as switch machines?

Mac B.

Reply to
polar bear

DING DING DING... Aluminum foil works and ages juuust fine...

Reply to
Big Rich Soprano

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