Well, after about 5 months of putting this project on the back burner while I built a steam powered Model-T Rail Truck, http://www.mylargescale.com/Community/Forums/tabid/56/forumid/11/postid/27647/view/topic/Default.aspx
I’m finally getting started again.
I’ve done some rethinking about my original plans. They originally called for a trailing car that would carry the locomotive’s only gas supply. It was also to carry an auxiliary water supply to be pumped into the boiler via a WLDS and pump. Instead of having to finish the trailing car before getting the locomotive running & on the tracks, I will be making the locomotive self-sufficient by adding an on board gas tank placed in the fake water bunker. Since I will eventually finish the trailing car, the source for fuel will be controlled by a set of valves (manifold) that will direct the fuel to the boiler’s burner from either the trailing car or the on-board gas tank. This requires the design and building of 2 on/off gas valves, a small manifold and the moving of Kevin O’Connor’s butane gas control valve from the trailing car to the locomotive itself.
Secondly, a valve controlled steam takeoff will be added to the boiler for the possible heating of the water surrounding either of the gas canisters and the steam valves manifold, if needed.
My first actions are to bring the existing designs up to my current thinking along with a new design for the on board gas canister enclosure, the gas valves manifold and the steam dryer assembly.
Here’s a sketch of the gas canister’s on board enclosure with the placement of the gas valves manifold:
Here’s my working drawing of the gas valves manifold:
And finally, the steam dryer assembly. As suggested in an earlier message by Harry Wade, the dryer assembly needs to be easily replaced. He also suggested
“In order to get the tube out of the firebox, is to make a core drilled bronze (or brass) header block, so that the Stainless dryer coil ends goes directly into the block without bends and the exterior side of the block has your two exterior connection points”. This should avoid making abrupt hairpin bends in the tubing. To this end, I will be machining a brass header to accept the stainless steel tube ring to fit just inside the firebox adjacent to the burner’s flame and the appropriated fittings necessary for easy removal & replacement. Here’s my drawing:
This will require silver brazing stainless tube into the brass header. So, if anyone has any suggestions on the techniques for brazing stainless to brass will be appreciated.
So, while I’m waiting for the order I placed for supplies/metals I need for the above, I will make some more progress on the bogie frames, the axles, the drive line/universal joints, then machining of the wheels.
Once the universal joint parts were removed from the casting sprues, some additional cleanup cutting & filing was required. Then the barrel was turned down, chucking up on the barrel’s sprue, to fit the inside diameter of the rings. Then that sprue was parted off. The newly turned barrel was chucked up and a 1/8” hole was drilled & reamed through the center of the barrel to fit the final driveline. A hole was drilled & tapped through the side of the barrel for set screw to secure the barrel to the driveline.
The universal takes the 2 sets joined together with a short piece of square brass channel slid over the square shanks. Here I’m showing one side of the universal assembled and the other side ready to assemble.
Each of the Locomotive’s 2 bogies have 2 shaft hanger castings through which the 1/8” driveline and 3/16” axle passes and is designed to keep the 2 gears (a 40 toothed spiral beveled crown wheel & a 20 tooth pinion) in 90 degree alignment. The shaft hanger’s hole for the axle is reamed to .1890” for a running fit, while the driveline hole was reamed to .1285”, also for a running fit.
On each 2 1/2” x 3/16” dia. axle, a keeper bushing was machined from brass rod to keep the shaft hanger in alignment (½” OD x ¼” wide with a 3/16” hole for the axle.) The keeper bush will has a set screw for securing it to the axle.
The axle length turned out to be very critical. In the design of the bogie, there’s no easy way to assemble the side frames with the upper pivot bolster in place along with the axles, consequently at the point in the assembly process where the axle & wheel assembly is placed in the journals, little or no play is available for the axles to slip into the journals. The 2 ½” axle is just 1/64” wider than the space between the journals. With the spring bolster, springs & bogie end stretchers (brake beams) removed, it still takes considerable twist exerted on the remaining bogie frame parts to allow the axles to pop into place.