"nightjar .me.uk" cpb@insert my surname here wrote in message
...

"John Rumm" wrote in message
o.uk...

I decided to go through the box of bits that I got with the ancient lathe
I was given. It seems like I have a lifetimes supply of cutters, various
face plates, a few widgets for fixing to stock and engaging with same
when turning stock between centres, plus the usual three and four jaw
chucks.

Now most of them I can make a stab at identifying, however there are a
couple of things there that I don't recognise. Here is one such:

http://www.internode.co.uk/temp/UnIDLatheObject1.JPG
http://www.internode.co.uk/temp/UnIDLatheObject2.JPG

Its probably about 2.5" by 1", and about 1/2" thick.

Any idea what one is supposed to do with it?




Not easy to tell from the photos, but if the tool bit is more or less square
section then it may be a home made version of the diamond tool holder or
tangential tool holder. This is a device where the end of the tool bit is
simply ground flat at an angle across the section, so that it looks like a
diamond shape. The rake and clearance angles are created by tilting the
tool bit rather than grinding them.



You can see a commercial version at
http://eccentricengineering.com.au/i...=2&Ite mid=18

and there’s a description of a home-made one at
http://www.gadgetbuilder.com/ToolHolders.html#Tangent