Bending Pipe & Tubing

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How to make smooth bends in tubing without kinks or collapses. About half a century ago, my old Grandpappy showed me how to make smooth bends in pipes and tubes without kinking them or making them go flat.  Now my Grandpappy had worked as a steam fitter for the Canadian Pacific Railway about a half century before that, so for once I smartened up and paid attention.  Now it's time to pass on his techniques from a century ago, and some more that I have learned since then. For large tubing and pipes, say 1/2" diameter and up, you can use an appropriate size bender or hickey if you can lay your hands on one.  But for an occasional bend where the price of a bender is cost prohibitive or the proper radius just is not manufactured, try packing the pipe or tube full of sand.  Do not just pour it in, ram it in tight, a bit at a time, using a ram rod (a dowel or metal rod will do.)  Plug or cap the ends then bend the tube around something of about the right diameter (your knee is not recommended.)  With iron pipe, it may be necessary to heat it red hot, either with torches, a bon fire or charcoal briquettes.  In this case, bending it around your knee is definitely not recommended!  Wooden forms are okay for a few bends but expect charring from hot pipes.  Once the pipe cools, knock the sand out by rapping gently on the pipe with a hammer, working from one end to the other. For medium tubing and pipes, say 1/8" to 1/2", a bender, if available is nice, but a spring that just slips over the tube will do almost as well.  For pipe with a substantial wall thickness, pouring it full of molten lead often does the trick.  Bend the pipe cold then heat it up to melt the lead out afterwards.  Experience indicates that allowing the molten lead to run out of the pipe and into your shoe is really, definitely not recommended! For small tubing, say 1/8" and smaller, the tubing usually will not collapse if wrapped tightly around a mandrel that is at least four times the tubing diameter. For example, with 1/8" outside diameter tubing, the mandrel should be 1/2" diameter or larger. Bending near the end of a tube or pipe requires some method of holding the short end.  For the smaller sizes of tubing used in model railroading, a quick trick is to use a piece of steel rod or shafting as a mandrel and a piece of smaller diameter rod as a clamp.  Hold the two pieces of rod side by side and clamp them vertically in a vise.  The larger rod should be toward the ends of the jaws and the lower end of the smaller rod should rest against the screw or the slide of the vise.  When the vise is tight on the larger rod, the smaller rod can still tilt away from the larger one at the top, but not at the bottom.  Put the end of the tubing between the rods with a little bit (about one tubing diameter) sticking through.  Then hold the tops of the rods together, clamping the tubing between them.  Now you can wrap the tubing around the larger rod, keeping some tension on the tubing to keep it tight against the rod.  With a minimum of practise, this method will turn out perfect bends every time. If many bent tubes are required, it may be worth while to make a more permanent bender.  One way to do this is to pile some washers of the right diameter into a stack that is as high as the tubing's diameter.  Then add a fender washer to the top of the pile and slip another under it.  Bolt this whole mess to a piece of angle iron.  Clamp the other leg of the angle iron in a vise.  Wrap the tubing around the smaller washers.  The larger washers will restrain the sides of the tubing and help keep it from collapsing.  To use this bender near the ends of tubes, add a stop pin.  The pin should be spaced one tubing diameter from the smaller washers, and should extend through both fender washers.  Then the tubing can be slipped between the pin and the smaller washers to hold the end while the tubing is wrapped. These are only a few of the many ways of bending pipe and tubing.  But they should be enough to get you started on some railroad projects, or possibly some garden projects around the layout.  In conclusion, let me ask you the following philosophical question:  if tubes are tubular, why aren't pipes pipular?  (If you figure it out, let me know - I'm still trying!)