"Norman Billingham" norman.at.tumulus.org.uk wrote in message
...

"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.

Not so much home made, as the normal way of making tool bits before insert
tools.

Even when I started using insert tools, I still used to make up a number of
shaped plunge turning tools, which were often a lot quicker way of making
complex shapes. I also have a couple of turning tools made from a length of
silver steel inserted into a file handle. They were used with a T tool rest,
to turn metal by hand, in much the same way as wood turners turn wood.

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.

If you look closely at the photos, there appears to be some top rake ground
in.

Colin Bignell