Scratchbuilding Idea - Scale Sheet Metal Work

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.

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.

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.

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 year...lol.

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.

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.

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