Cylinder Drain Cock Outlets

Lenghtened water valve levers on a Feldbahn steam locomotiveAs soon as I started to drive my new Feldbahn from the steaming bay I spotted a problem.  The very first Stafford locomotives like my old 'Gentoo' had cylinder drain cocks that squirted vertically down, so although they ended up splattering the underside of the loco with trackside rubbish they didn't spray my friends in the steaming bays (or worse members of the public in the station) with that nasty oily emulsion that always appears when the loco has been standing.  The photo on the left clearly shows the jet of liquid ready to soak anyone, or any other loco, unlucky enough to be in its path.  Not wanting to be considered antisocial by my fellow club members (or worse upsetting a paying passenger by scalding their feet or ankles) I decided that something had to be done and set about designing a solution.

The main problem was that I didn't want to replace the existing cylinder drain cocks, so whatever I did had to modify and not replace them.  A simple angled shield attached to the cylinder cladding was considered but rejected because it would have looked unsightly and probably have splashed the emulsion all over the underside of the cylinders and chassis.  Measurements showed that there was insufficient material on the drain cock body to screw in pipe unions for outlet pipes, and if pipes had simply been soldered on it would have been impossible to screw the drain cock bodies back into the cylinder casting.  The answer seemed to be an outlet pipe held to the drain cock body by some sort of clamp, but the more I measured the more awkward this solution looked because of the position of the cylinder cladding.  Eventually I devised a solution, and although I could have directed the outlet pipes straight down I pointed them forwards (as often seen on full size locomotives) because generally speaking the track in front of a moving engine is clear of people.
Cylinder drain cock outlet pipes fitted to a Station Road Steam Feldbahn steam locomotiveThe photo on the right shows the pair of outlet pipes ready for fitting to the right hand cylinder of the Feldbahn.  The clamp sections were machined on my lathe from 3/4" hexagonal section bar and bored to be a good sliding fit onto the drain cock bodies.  On my Feldbahn this was exactly 12mm diameter, although I did have to use fine "wet & dry" paper to remove the machining burrs from the drain cock bodies before the clamps would slide into place.  My intention was to have the clamps as good a fit as possible around the drain cock bodies to avoid leaks.  The 3/16" OD copper pipes were bent on one of my home made pipe benders (see the bottom of this page) and silver soldered into the clamps.  Likewise the brass "figure of 8" section was silver soldered from brass tubing before being soft soldered onto the outlet pipe of the forward assembly.  The clamps are locked in position on the drain cock bodies by 4 BA socket grub screws.

A simple jig was used to hold the parts together while soldering, and the clamp section was drilled 3/16" diameter by 1mm deep to help locate the pipe.  The pipe "hole" was drilled 4mm diameter right through the clamp, and as the existing outlet hole in the drain cock body was only 2.6mm diameter on my Feldbahn this allowed a degree of mispositioning to be tolerated when attaching the clamps without blocking off the outlets.

Cylinder drain cock extension pipes fitted to a Station Road Steam feldbahn miniature steam locomotiveThe photo on the left shows the outlets attached to the Feldbahn's cylinder drain cocks.  To fit them the M3 socket cap head screws in the drain cock bodies and the operating bar had to be removed, which meant that the short push rods inside the drain cock bodies fell out.  My tip for replacing them is to overlap half their length onto a short bit of masking tape which can then be used to get them back into position while still allowing the M3 screws and operating bar to be fitted.  The masking tape can easily be pulled off before the M3 screws are screwed into the second side of the drain cock bodies.

Redirected cylinder drain cocks on a Station Road Steam Feldbahn 0-6-0Finally, here is a photo of the redirected drain cocks in action, and as you can see they do what I wanted by getting rid of the sideways spray.
Miniature Pipe Benders
Miniature pipe bender for model engineeringThe outlet pipes needed to have a very tight bend radius which none of my commercial pipe benders could produce so I had to build yet another pipe bender (this is my third).  All of my benders follow the same basic design as this one (shown in the photo on the left) although those for larger diameter pipes (5/16" and above) incorporate another bar across the top to "stiffen" the bender.

The main handle is cut from steel angle, so that the upright section locates the pipe while being bent.  The other handle has a brass die block bolted to it which has a half round hole on the "bending" face the same diameter as the pipe to be bent.  The slowest job in building these benders (at least for me) is accurately grinding the form tool to be used on the lathe when turning the mandrel around which the pipe is bent.  The quality of the finished pipe depends on getting a precise half round groove turned into the brass mandrel.

The working parts of the minature pipe benderThe other photo shows a close up of the working parts of the bender.  By carefully positioning the pivot pin the mandrel and die block end up completely surrounding the pipe, and the upright angle section will be supporting the outside of the pipes diameter.  If the supported length of pipe is short (and straight) it often helps to insert a close fitting drill shank into the pipe end to stop the pipe distorting as its forced against the upright angle, but don't let the drill get too close to the start position of the bend or the pipe will develop a bump (or even crack open) rather than forming a neat bend.

With the
3/16" x 26 SWG copper pipe correctly annealed this bender was able to produce bends with an inside radius of only 4mm.

If like me you have a "scrap" box full of odd lengths of material you will probably have all you need to construct a pipe bender, and thus be able to save money instead of purchasing a commercial item.  Another benefit of this design is that the pivot bolt can easily be removed to dismantle the bender and thus extract pipes with bends close together.  Both the commercial benders I own are riveted together with the result that it is often impossible to get bends close enough together.