I own a Brazilian made Nardini 350 lathe with an L00 spindle nose. This style of spindle nose includes a taper, a threaded locking ring and a key way. The locking ring pulls any attached chuck or faceplate tight against the external spindle nose taper. The locking ring is rigidly held in place when a chuck or faceplate is fitted. If a collet chuck or other tooling is fitted to the internal taper of the spindle nose, there is nothing to hold the locking ring in place and it will loosely revolve and rattle when the spindle is powered up. In addition, the exposed key on the external spindle nose taper is a snag hazard. The usual solution to this problem is a spindle nose protector. These provide something to hold the locking ring in place and to cover the spindle taper key. They also protect the precision ground surface of the spindle nose taper.
The traditional method of making a L00 spindle nose protector is to start with a large piece of plastic or aluminium bar and then convert most of it to swarf. I decided to take a more modern approach and use 3D printing to make the one shown in the photo. In contrast, creating 3D items starts with nothing and then objects are created additively. This is true within the CAD programme and then the additive 3D printing process.
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Download the STL model of the protector in this zip folder.
Thanks to Darren Conway for making his STL available.