MYFORD VM-E CNC RETROFIT

摘要

In the last Issue of MEW, (No 118) I described the application of ballscrews to the X and Y axes of the machine. In this concluding part, the conversion of the Z axis is considered. The Z axis was always going to be a bit more tricky than the X and Y feeds as there was no existing leadscrew to replace and I wanted to retain the option of using the lever operated drilling function. This latter is really useful for large diameter drills with Morse taper shanks or for coordinate drilling. Photo 1 shows the quill arrangement. On this kind of vertical mill it is raised and lowered 90mm or so by a horizontally mounted gear which engages with rack teeth cut into the back of the quill. The gear is mounted on a shaft which carries the downfeed lever on the right hand end and a wheel on the left hand end which engages with a worm on the micro downfeed shaft. Clearly this worm and wheel must be capable of being disengaged so that the downfeed lever can work. This is done by an axial thrust, screwed collar on the left hand end of the shaft bringing the gear in and out of engagement. None of this immediately lent itself to a ballscrew drive.