- Jun 15, 2010
- Reaction score
- South Leicestershire, England
Hi K2,Terry, On the subject of the tool cutting point set 5 degeers above the centre of rotation of the workpiece:
Suppose a 3 to 4 degree clearance on a tool. It will rub at the contact tangent on the workpiece if 5 degrees high. But only start cutting if 5 degrees or more clearance angle.
Also the rake angle will cage per the 5 degree offset. So a zero angle rake on a tool becomes 5 degrees of rake, a tool selected withe 3 degrees positive rake will become 2 degrees negative rake, a 5 degree negative rake will become 10 degrees working rake, etc.
Sorry. It seems crazy to me.
Can anyone explain? IT's not just a language problem....
I think that it's just to take care of the 'spring' in the tool and workpiece - and no matter how 'rigid' e think that is there is always some slight movement in response to the forces involved, so if the tool is forced downwards it presents itself to the work as if it was on centre, at least that's all I can think of. Having said that as you say trial and error is important but so is a starting point especially for a tyro like John.