< Outer Crossheads 1 >
In order to combine the main rods with the pistons, it needs slide bars and crossheads. First I prepared two outer sets.
Outer slide bar has T shape with wide front end and square body. The two parts are prepared separately and silver soldered before cutting. The square body is made from 13 mm silver steel square bar. Before soldering, the two parts are temporary fixed with brass screws.
Both ends of the square part are shortly peeled and cut obliquely. They are cut by end mill in a vise. The flute is cut in the same way as the main rods.
Grind whole body and drill holes for screws, then the slide bars are finished.
The drawings show outer crosshead. Slide bar is put between upper and lower u-shape parts and they are also put between two side plates. The lower u-shape part is silver soldered to both side plates, while the upper u-shape part is fixed by penetrated bolts. Each u-shape part is covered with a phosphor bronze sheet for wear resistance. A bush for piston rod is silver soldered at its lower front end. A pivot for union link is set at its bottom.
The side plates have complicated form. I ordered laser cutting parts. Cut steps in both sides and drill necessary holes.
The u-shape parts are cut from steel flat bars. They also have complicated form. Cut each face one by one.
The bush part is cut from round bar. After cutting rectangle part, chuck the rectangle part and turn bush part. The rounded bush part is turned by inching tool in calculated minute steps and finished with a round file. Center hole is not opened at this point.
Before silver soldering, all of parts are temporary assembled with brass screws. The photo shows one side plate with two inside parts.
Whole parts are silver soldered at a time.
The phosphor bronze sheets for wear resistance is 0.5 mm thickness. Both ends of each sheet are bended in order to avoid slipping out.
The slide bar is put into the crosshead and the upper u-shape part is push softly against the lower u-shape part. Then the upper u-shape part is drilled through the side plates. Drill half in depth from both sides and open hole at the center in depth. The sliding tightness can be adjusted by screw holes' play.
The crosshead has a dummy oil box in front. It is made from rectangle bar and its rounded edge is cut in rotary table.
The oil box is fixed on the crosshead by 1.4 mm screws. The oil pipe is made from 1.2 mm copper wire.
<To be continued>