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chattering tools

updated mon 23 apr 01


iandol on sat 21 apr 01

I think there is a need to call in the services of a Fitting and Turning =
Engineer to resolve this problem. It is a universal torment for anyone =
who is doing any form of Lathe Work. It can even happen when you are =
doing Cylindrical Grinding. Furthermore, it is a problem for which I do =
not have an answer.

Having said that, from the limited understanding I have, it has =
something to do with harmonic motion and can occur when the object being =
turned is not secure or the tool is not secure and rigid. It may also be =
connected with the angles to which tools are ground as well as a =
relationship between the angles at which a tool is held and the angle of =
the cutting edge with the work. Reference to a book about Lathe Work may =
give a full answer.=20

I would suggest changing the way tool is held so that its blade is at an =
angle to the axis of rotation rather than being at right angles to that =
axis. I would also try to get the clay to Shave rather than Hack. When =
the tool chatters it pecks into the work. This sets up harmonic =
vibrations which reinforce the motion. If the clay is drier rather than =
leather hard it should peel off, breaking into regular chips, if softer =
it should peel into a continuous ribbon.

Any Tool Manufacturer who is using a material as expensive and as hard =
to fabricate as Tungsten Carbide will have researched the best angles to =
put on the tool to get the optimum cutting speed with the least effort. =
I would ask for diagrams to illustrate and instruct about the best tool =
angles and choice of cutting speeds.

Best regards,

Ivor Lewis. Redhill, South Australia