< Main Cylinder 2 >
Cylinder covers are drilled through the jig that I introduced last month.
Back cylinder covers should be aligned so that the bolting face of slide bar becomes horizontal. The photo shows how to do it. In case of the inner cylinder, the tilt jig for boring process can be used again.
The cylinder block is countersunk through the covers. After removing the covers, the cylinder block is drilled and tapped.
The cylinder block casting has no flange for the covers. So the cover bolts are arranged in smaller dia. than the prototype. The bolts will be hidden with jackets later. Incidentally, model locomotive cylinder bore is often smaller than the reduced scale of full size locomotive. Because we don't need scaled power of the full size, as far as we drive it at scaled speed.
Top plate of the cylinder block is also made of gunmetal casting. It has slopes at both sides to hold the smokebox. First, the bottom face is cleaned with end mill.
Top face is cut to final thickness.
Holes for bolts are drilled. Position of each hole is located by X-Y dials of the milling stage.
Finally the top plate is bolted down onto the cylinder block with countersunk head bolts. Steam outlet port is not opened yet. It will be at the center of the plate.
Due to a long business trip, I suspend this blog for several months. I will return within the year.