Pattern Making for the Beginner's Locomotive
An 0-4-0 Switcher of Simple Design
The Miniature Locomotive, January-February 1953
Well, now that we have the frame done it will be as well to start on the cylinder pattern so they can be cast while you get on with other work. It doesn't really matter what material you make the pattern from as the softest woods will last for many castings. I made them of cedar mainly because the mill where I am engineer cuts only cedar, but white pine is the best pattern wood.
While pattern making is a fine art, castings can be designed for model building to employ very simple pattern making.
The first thing is to form the cylinder barrel and core prints. To get this pattern out of the sand it must be done in two havles, so you need two pieces of wood 7/8 inch by 1-3/4 inch by 7 inch with two of the flat faces planed up true. Screw these together with about a No. 10 wood screw about 1/2 inch from each end. Mount in the lathe with the center right on the dividing line of the halves. Leaving enough wood square at each end to hold the screws turn the middle to 1-1/2 inch diameter, full. Then makr off the flanges 1-3/4 inch apart and 3/8 inch thick. Turn down the space between flanges to 1-1/4 inch diameter and the core prints on each end to 3/4 inch diameter. Leave a slight taper on these flanges so they will draw out of the sand easily. Transfer to the drill press and poke a 3/16 inch hole through the core print on each end deep enough to enter the mating half about 1/4 inch. These are to take dowels to line the two halves of the pattern when in the sand.
You now want to flat seat on top of the cylinder (the half that the dowels just enter) for the port face block to glue onto, so run a pencil line along each side of the square ends 3/8 inch above the parting line. Grab in the vise with this line level with the jaws each side and you can hold the pattern without damage while you saw down each side and pare out with a chisel a flat 2-1/8 inch long. Finish with a file, when the file just touches the vise it should be level and at the right height. Now you can saw the square bits of wood off each end leaving the core prints beveled. Make the port face block 2 inch by 1/8 inch full with about 1/32 inch taper up to the top again to ease it as it is drawn from the sand. This can now be glued on and a make-up piece of 3/8 inch wood is fitted to fill in from the port block to the parting line. Glue up. There will be a little niche at each end where the port block fits into the cylinder flange on the outside which must be filled with paster of paris or plastic wood; even wax will do. Also fill any crevices between port block and cylinder forming a fillet where each joins it neighbor. File the outside corners of the port block rounded when viewed from the above. Sand paper smooth, give several coats of clear shellac, sanding between coats until you get a hard, smooth finish. Add a little lamp black to some shellac and do the core prints and the center in the parting faces a strip through the cylinder representing the cored portion of the bore.
So much for the cylinder pattern, we now need a back cylinder head. Cut out a circle of 1/4 inch three ply 1-5/8 inch diameter. Saw out the gland boss and guide bar seat from 3/8 inch wood and glue this one the center of disc. When dry drill a 1/4 inch holde 5/16 inch deep in from the back in the dead center. Now turn the chucking piece with a 1/4 inch spigot on the front to fit freely into the cylinder head and give it 1/16 inch taper making the opposite end smaller. Shellac and finish same as the cylinder pattern.
You can get these cast in bronze if you wish but I prefer cast iron, which won't rust if it is given enough out.
It's lots of work to make a driving wheel pattern and as only four castings are needed, beginners may as well buy them. Don't use blank disc wheels; I think they look awful.
The wheels on our local switcher are for the English locomotive Juliet, designed by the father of miniature locomotives L.B.S.C., and were from Kenions of England.
Having made it known that a U.S. supply might be welcome, I am more than pleased to say that Dick and Bob are going to accommodate us through the Miniature Locomotive Company. They are now prepared to supply castings for cylinders and drive wheels. I hope they will see their way clear to provide a saddle casting and the domes and stack and possibly a smoke box front to make the set complete.