I've got a part I'm making that I need to hold by the ID for external post anodize machining. I'm cutting decorative flutes with a full radius carbide saw blade, the small diameter to reduce how far the mandrel will have to extend beyond my indexer. Using a Hardinge Universal dividing head. Not only is this not really ideal for a traditional 5C expanding collet, I haven't found one that extends 2". Royal declined to quote a special despite my assurances cutting forces were very low.
In searching for an answer I did run across some nice hydraulic expanding mandrels. I am sure they are out of my price range, but got to wondering just how hard it could be to make one. I want to hold a .592 dia along the better portion of it's 1.3" depth, and have a thru hole in the end I hope to use to access the screw that provides the hydraulic pressure.
The decorative fluting is cut into contoured profiles on the OD of the part and any significant runout results in cuts of different lengths. Reason for thinking hydraulic expansion is to improve the runout, and to provide better support for the part to avoid possibility of vibration/chatter. Been doing the prototypes on a solid mandrel with a screw/washer through the end to clamp. Works, but not ideal.
Anyone do anything like this before? Have any better ideas?
Thanks,
Jon