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For many years chucks, faceplates and catchplates were simply screwed onto the end of the lathe's spindle; a bewildering variety of types and sizes of thread were used and non were standardised between manufactures. Although cheap to manufacture and perfectly adequate for most purposes, especially amateur use, threads do have serious limitations centred around safety, rigidity and ease of removal and replacement. To take just one example: a threaded fitting cannot safely be run backwards and, whilst a chuck might happily stay in place as a lathe accelerates up to top speed in reverse, once there it cannot be so easily stopped. Legion are the number of serious accidents caused where an operator has stated a lathe in reverse, realised his mistake, and then (without thinking) applied the spindle brake. Once the chuck starts to unscrew the workman can do nothing but watch in horror as the 200 lb mass, rotating at 800 rpm, accelerates down the length of the workshop smashing machines and people unfortunate enough to get in its way. To overcome this, and other limitations of threaded fittings, many alternative designs have appeared over the years that are safer, more rigid and both easily mounted and removed.: the following pages illustrate the most popular and frequently encountered types for both direct and backplate mounting. To understand the fitting look through the links to both Spindle Nose Fittings and Backplate Fittings.
SPINDLE NOSE FITTINGS American long Taper with Drive Key and Draw-nut Types L00, L0, L1, L2 and L3 AMERICAN STANDARD SPINDLE NOSES - Direct Mounting American short Taper with Bolt or Stud Fixing Types A1, A2, B1 and B2 American short Taper with Camlock Fitting Type D1 British and ISO Standard Spindle Noses - Direct Mounting British & ISO Short Taper with Bolt or Stud Fixing British & ISO Short Taper with Camlock Fixing British & ISO short Taper with Bayonet Ring Fixing German Standard Spindle Noses
BACKPLATE FITTINGS Cam-lock D1-2", D1-4" etc American Long Taper L Types L00, L1, L2 and L3 Short Taper A-1, A-2, B-1, B-2, with Bayonet "A Type" Screw Fitting
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