< Cylinder Block Cutting 1 >
I started cutting of the cylinder block. At first, top reference surface is cut by milling machine. Before clamping, I adjusted packing at four corners to hold the casting truly horizontal.
The job is reversed and three faces of the bottom channel are cut. Side faces of the channel become side reference. Note a steel round bar standing near the right cylinder, that is as a gauge to finish the top face in desired height from the milling stage. Here I also cleaned bottoms of the outside cylinders.
I will mount the casting on the lathe table and finish cylinders and valve chest bores with boring bar. But the casting is too wide to clamp onto the Myford S7's narrow table in the usual manner. So I made T-slot extension nuts as shown in the photo. Some weakness cannot be avoided.
Reversed and mounted on the table, the valve chest center is coincide with the lathe center in height. Then the valve chest is aligned truly parallel to the lathe bed with DTI in the tailstock.
First, valve chest cover bolting faces are finished with a fly cutting tool, that is just a knife tool in the tool post gripped by four-jaw.
The boring bars are prepared from 20mm silver steel rods. At the middle of the rod, a boring tool is hold in a cross hole and secured by set screw. Both ends of the bar are center-drilled.
Thin boring tool for valve chests is made from 5mm HSS drill.
After removing unwanted walls in the valve chest by a hole saw (refer the last month report), I started boring. The bore diameter is expanded from 25mm to 33mm with 0.4mm steps.
The tool diameter is adjusted with suitable block and plates between the tool and lathe bed.
As usual, I employed limit switch to stop the lathe motion at the end position.