Eminent Technology ET-2 Tonearm Owners

OD is 'outside diameter'.
ID is 'inside diameter'.

Chris
Good to read about the mag wands performance. Thanks for giving us a clear view on what it does. Also impressive engineering all over again from Bruce.

Thanks Henry – its the words turn and bore that are intriguing to me.
Richard - I would like to see a video of this whole process.
I have seen many videos of how records are made and have been to one record plant many years ago.
The old record making videos always show a bunch of ladies at the end of the process just prior to inserting them into sleeves; They could all pass for your Aunt (fill in the name). They represent quality control as they eyeball the records. :^)

Chris.
When Bruce machines the wand, I assume that this is what happens...
The bore thing is basically drilling a hole to create the ID dimension. Sometimes the drill is rotated, some times the work piece (bar) is rotated. It depends upon the machining centre. For complex internal shapes it is possible to undercut the workpiece such that a larger ID is created say in the center section compared to the two ends of the resultant hole.
The turn process is like moving a chisel along the outside axis of the spinning bar to create the OD dimensions. The chisel can be moved in and out to create different ODs along the length of the bar.

I could send you a video of our milling machines running but you don't see a lot as the work piece is flooded in cutting fluid to keep it and the tools cool, lubricated and help with swarf removal.

The art in this process is getting the feed ( how fast you pass the cutting tool along the surface ) and speed rates ( how fast you spin the work piece or cutting tool ) optimized to produce the required tolerances and surface finish, in sync with the conflicting requirement of finished product thru put, tool wear, and machine loading.