I'd like to make my own R8/CAT40 ER chucks to save money if possible.
I'm assuming as long as one has a 4 jaw independent chuck, rigid enough of a lathe, CNC program/s with .0001" or better deviance, an indicator, and plenty of patience or spare stock this is theoretically possible.
Or are tolerances these tight really down to sending them out to get ground?
They are generally machined (on a multitask machine), Hardened then ground to achieve such tolerances, and its not just the diameter tolerance that you have to meet but the form of the taper as well. Its not very practical for you to do yourself. You will spend more money than if you just bought one. If your looking to save money try looking on ebay. Video of the process of making them can be see here, MariTool Factory Tour! How they make CAT40 Tool Holders!
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