OK I'm now going to make the large tension adjuster knob, I have placed a small piece of 25mm brass bar in the lathe chuck and have started roughly cutting the knob to to shape it has already had a centre hole drilled in the end.
This is a real hacking job, no finesse just turning away until the rough shape emerges, but you can see the bottom ring of the knob is now at the right size as is the top ring where the knurling will go.
And now to make the lovely shaped waist lines that the old key makers loved, to do this I use a Rat tail file !! there are probably more technical ways of doing it but I like to use old Ratty :()
And here is the lovely smooth waist made by old Ratty, time now to quickly drill and tap the knob before it is knurled at cut free
Tapping the knob is very easy when it is in the lathe as by inserting the tap and slowly rotating the lathe chuck by hand it can be kept central as it screws in, I'm using a 2ba tap here.
Time now to knurl the knob, this is a very satisfying job as a knurl puts a nice finishing touch, the knurling tool is simply placed in the tool holder and presented square to the face you have prepared for it, start the lathe and gently apply the tool until you reach the depth of knurl you want.
here is the knurled finish, not a good picture as the reflected light from the knurl seems to affect my camera?
Anyway below is the completed knob cut free and faced, even a slight dimple has been added to the top
And below the adjuster has been placed where it will go when I reach that stage in the construction, which is some way off yet but it looks good :()
Time taken to make 20mins  I expect a Japanese machine could have pumped out two thousand of them in that time :)