Main Frame Design III
This page is a continuation of the Frame design II page and shows the design of the front sill and associated parts and the boiler supports.
Front Sill & Associated Parts: The photo above shows the front sill on Cass 6. While preparing this design I reviewed the photos of Cass 6, MRSR91 and parts from a slightly smaller late Heisler. The drawings I did for Cass 6 show both the locomotive front sill and the tender rear sill are 10" X 13". The review of the photos confirmed that tender sill as 10" X 13". The locomotive sill was also measured as 10" thick. However, the height was measured as 14.5" at the center and 13.5" at the ends. The photo above shows the bottom of the sill is flat between the vertical foot board supports and slopes up slightly toward the ends. I never noticed that before! All the photos and drawings of other Heisler Locomotives suggest the sills did not have tapered ends. Possibly the tapered ends were done when the sill was replaced a couple yeas ago. I decided to make the model locomotive and tender sills identical at 1.375" X 1.875" X 16". Hopefully I'll be able to find a suitable piece of maple or cherry.
Front Sill Bracket: Drawing above shows the front sill bracket design. The main piece is a 12.5" length of 1/8" X 1.5" bar stock. The smaller pieces that protrude from the plate will be cut from bar stock and silver soldered in place. This drawing was updated 1/9/2007 to reflect minor changes made when the piece was fabricated.
Front Coupler Support: The front coupler support shown above will be constructed of 1" thick and 1/4" thick bar stock. The plates on the ends will be screwed and silver soldered to the central bar.
Boiler Supports: The photo above shows the rear boiler support on a late Heisler. The end pieces are castings and the cross piece is a steel bar. The dangling thing in the center is a piece of wire. The photo has been edited to white out background clutter around the support to make to show up better. The bottom of the boiler (mud ring) sets on the castings. The bar probably keeps the castings from twisting under load and also holds the dimension between the frame sides. The rear support is hidden under the cab so this piece on the model can be made a bit simpler. The outside of the castings are visible on the front mount as well as mounting facilities on the center stiffener that I'll want to reproduce on the model. The cross bar will interfere with the oil burner nozzle so it'll have to be repositioned slightly.
Rear Boiler Support: The rear boiler support is made from a piece of 1.75" X 1.5" X 3/16" angle. I'll probably have to buy 2" angle and cut it down. The support bolts to the bottom of the lower frame bar just in front of the rear stiffening plate. The bar will be positioned such that there is a 1/4" gap between the vertical side and the back of the boiler. The boiler will be bolted to the saddle so any expansion will cause the back of the boiler to move to the rear. I expect at most 1/16" of movement between hot and cold.
The top of the vertical part of the support also serves as a support for the cab floor. The rear of he boiler doesn't seemed to be clamped down on the prototype. For the model, I plan to screw a couple 1/4" bolts into the back of the mud ring and run the bolts through holes in the vertical part of the support. The bolts will extend beyond the support and not be tightened against the support. This arrangement will permit the boiler to move back and forth slightly to accommodate expansion and contraction but will restrain the boiler from moving side to side or to lift off the support vertically.
This boiler support is also a brace for the side channels. The ends fit under the channels. There will be a 1/16" gap between the boiler support and the channels which will be filled with suitable shims. Screws up through the support into the channel flanges will secure everything.
This sketch above shows the frame with all the parts in position. This beats the frame design to death; time to start making some chips.