< Boring for Flanged Plates >
The locations of holes in the flanged plates are scribed on the basis of the formers. Reproduce the setup of former, cover the former with the flanged plate and scribe each position on the flanged plate. In case of the backhead, the former is tilt by the tilt base plate on the rotary table. Horizontal and vertical lines are scribed at a time by rotating the rotary table.
When scribing the firebox tubeplate, the former is mounted directly onto the rotary table. The smokebox tubeplate is mounted on the former on the lathe faceplate and scribed calculated height from the lathe bed.
Small holes for the stay are drilled directly. Holes for the bushed are finished with reamers.
A large hole for the regulator bush is opened by a holesaw. Holes by holesaw have inexact diameter and also their roundness is not good. In case of the regulator bush, surface of its flange is fully silver soldered onto the backhead surface. Therefore the hole's roundness is not important.
The backhead and the firebox backplate are connected by the firehole and the back stays, so the holes for them are opened at a time. Drill a small hole in each plate at the center of the firehole, align them with a pin and clamp them together.
Fix both plates on the stage and drill the holes for the backstays through from the backhead to the firebox backplate.
Fix both plates on the lathe faceplate, open a start hole with a holesaw and finish with a boring tool. The backhead was the maximum size that can be turned in Myford Super-7 lathe.
The photo shows the both plates removed from the faceplate after boring. The both plates are fixed each other with four bolts. Additional three long bolts are to fix whole job on the faceplate. Each has spacing nut and washer in order to pass the boring tool through the plates.
The photos show boring process for the smokebox tubeplate. The holes for the long stays are just drilled. The hole for the regulator bush is opened by a holesaw. Its roundness is not important, too. Holes for the tubes are not opened yet. They will be opened together with the firebox tubeplate.
The photos show boring process for the firebox tubeplate. The holes for the front stays are drilled. For the tube holes, only small starting holes are drilled here. They will be finished with a homemade boring bar that will be introduced next month.
