Machining the Injector

Before machining started, a redesign was in order to make it easier to machine the small injection orifices for the impinging streams. The problem was that three .028" holes needed to be drilled at a 30 degree angle. This is already a difficult task but the equipment I have to my disposal wasn't going to cut it because I had no accurate way to hold a drill bit that small. So, the three orifice design was scrapped and replaced with a single central orifice that is .047" in diameter. This orifice is perpendicular to the injector face and is impinged by the same three oxidizer orifices.

After the redesign, it was time to start working on machining the different geometries that make up the injector. The first thing to be accomplished was to face off both ends and machine the disk to the proper width. After that was complete, the center boss for the o-ring was roughed out and the recess was cut. The whole recess was not machined to the drawing specifications because it was very difficult to get the tool bits into that small space which I had not realized initially. The face o-ring groove was cut and the final diameter of the center boss was turned and then the o-ring groove cut as well. The part was taken out of the lathe and centered in the rotary table to drill the bolt circle and the injection orifices. The pictures below outline the entire process.