Heisler Engine Construction Part II
Valve Linkage Parts
Nelson Riedel, Nelson@NelsonsLocomotive.com
9/13/2009, last updated 09/15/2009

The engine is now complete and operating so it's time to document how the parts were fabricated.  Some of the parts described in this page were made a couple years ago (fortunately I finally found the photos) and others were made in the past month.    The technique of building up complex pieces by silver soldering simpler pieces together is copied from Kozo Hiroaka.   Many photos and few words is the easiest way to tell this story.       

Rocker Arm Base - HM127.   The rocker arm base is described the Engine Design VI page.   The base is partially hidden on the engine and is difficult to envision even if it wasn't hidden.   The drawing on the right shows how the base was broken into 6 much simplier shapes
This is the 6 shapes.   They are fastened together with screws and then silver soldered.
This show silver soldering three of the pieces for the upper part.  Two of the pieces for the lower part visible in the back have already been soldered together.
The next step was to solder the upper and lower parts together.  The parts were thoroughly cleaned in pickling solution (or bead blasted and the joints  fluxed) between each soldering step.  The parts were held in place by a brass screw during the soldering.   The screws keep the parts together when they are reheated to add additional pieces.
The last step was to add the thin fin to the top front.  A grove had been milled in the larger piece below the fin to keep it in position when it was soldered --- no screws were used on this piece.
The finished base ---- this one turned out really nice --- its a shame it's nearly completely hidden.
Tumbling Arm-HM134: The tumbling Arm is described in the Engine Design VII page.   The arm is made up of 1/8" thick plate and cylinders for the hubs.  Note that there are three stepped cylinders and three plain cylinders.  The plate will be sandwiched between the stepped and plain cylinders.
This shows soldering the stepped cylinders (large part up) into the plate.
The next step was to turn the plate over, support the stepped cylinders on the fire brick and solder the the plain cylinders onto the part of the stepped cylinder sticking through the plate.  The stepped cylinder were made extra long.  The excess will be filed/sanded off later.
The next step was to saw off the excess plate and clean up everything. There is still some excess to be sawed off the ends.  The final step to get the shape finished was to round the areas around the hubs with a file/belt-disk sander or small sanding drum in a rotary tool.
This shows the finished tumbling arm positioned on the rocker arm base.  Holes still need to be drilled and tapped for setscrews in each hub.
Tumbling Arm Lever-HM135: The tumbling arm lever is also described in the Engine Design VII page. The photo are right shows that the basic arm and hub are made using the same technique used for the Tumbling Arm.
The little hub on the end is in a different plane than the main part of the lever so it is made using a separate piece.  Notice that the main lever is notched so that the two pieces can be positioned for soldering.
This photo shows the lever after it was cleaned and the small end filed/sanded to give it the appearance of a casting.
A close-up of the small end after smoothing.
A front view of the three parts just described.
A side view of the three parts just described. These three pieces were fabricated in 2006 but not documented until the fall of 2009.  (There was a house and shop move in between.)
Reverse Link Hanger - HM136.  The reverse line hanger is also described in the Engine Design VII page.  This part is made by soldering a 1/2" diameter cylinder to the end of a piece of 1/2" X1" flat stock.   The photo shows using an end mill to cut a half round recess in the end of the bar stock.  Taking small cuts ---- ~1/16" and  moving the mill vertically like a drill seems to work best for me.
This shows the parts to make both the hangers.   Machining the bar stock for both hangers as one piece saves time.  (Making one part is fun -- making the second part starts to get boring.  Doing as many parts as possible in one set of operations keeps boredom away.)
The two cylindrical ends have been soldered in place here.
The next step was to saw and mill flat the sides.  The large center piece helps hold things during these operations.
The assembly was sawed in half next.  The hubs on the sawed end were then rounded on the end mill using the technique shown on the right.  A rod the same diameter as the hub ID was fastened vertically in milling vise.   The end of the rod was threaded for a SHCS. (1/4"-28 in this case).   The hanger was then placed over the cylinder and secured with the screw. The hanger was then moved against the end mill and rotated to round the hubs --- one  side at a time.  Note the leather glove to protect the operators fingers.  The part should be rotated in the same direction of the end mill is turning so that it is not drawn into the mill.  A better technique might be to use clamp pliers on the hanger to rotate it ----- thus keeping fingers out of harms way.
I forget to take a photo of the finished arm so instead took one of the arm installed on the engine.  Note that it has been painted, sleeve bearings have been  pressed into the hubs and oil holes drilled into the hubs.  This does resemble a casting as planned.  Unfortunately it is more or less hidden under the boiler.