Tool identification

Ive just got my first set of hss lathe tools and have a couple of very noddy questions.

It comes with a right and left handed turning tools. They have a groove ground into them. When mounting the tool does they groove go on the top or leading face? It looks, to me, like they would cut in either orientation. Photos below:

And what is this for?

Thanks

Colin

Groove to the top, bottom tool is for chamfering.

Tony

Hi Colin the groove is on the top of the tool on all three tools. I use this style on softer materials aluminium or EN1A steel for instance to get a good finnish and the third style I would use that as a roughing out tool for the same as the top groove acts as a chip breaker as well.

David

Thanks for the replies

Might be wrong but I've always assumed the groove to be a chip-breaker. It's purpose is to snap the long spirals of swarf that otherwise get entangled or form clumps. Chips are easier to clear than spirals.

A swarf ball catapulted by the chuck once hit me hard enough in the face to draw blood. Since then I wear eye protection and clear swarf before it builds up.

Dave

Just back from trying out my new lathe tools. The turning tools in my first picture are ground to a sharp point. Can I put a bit of a round nose on it or does the chipbreaker groove mean this isnt sensible.

I like the look of the groove cut into these tools,, I wonder if one could cut the same with a worn angle grinder disc may be worth a try?

Regard Bee.M

Hi Colin don't try and put a radius on the cutters with the chip breaker as they will rub and you can't get center height correct. Just grind off the end of the tool and a rub with a sharpening stone on the cutting edge. I use the corner of a grinding wheel along the groove and sometimes use a small diamiter grinding point in a dremmel to smooth it out. Don't use on brass, bronze, cast iron or similar materials as they will grab and chatter.

David

Edited By David George 1 on 17/10/2021 15:41:06

David - thanks for the detailed response

These look remarkably like tools that I bought from our favourite Leicester based supplier and come as a set in a neat wooden box.
When I attempted to use this knife tool I got a lovely finish when facing, but an appalling one when turning along the axis. Contrary to the advice above, I found that very slightly rounding the business end of the tool produced a near-miraculous improvement in finish.

If a tool is to cut properly, it needs to be mounted so that the cutting edge is on centre height.

A slight radius on the cutting edge will improve surface finish, but must extend down the edge to ensure that only the point contacts the work, to prevent the lower part of the tool rubbing.

With regard to describing the hand of the tool, when the tool is mounted, if the edge points towards the chuck, to cut, it is a Right Hand Tool A Left hand Tool faces towards the Tailstock.

Think of it as if you are looking on the point of the tool from the other side of the lathe.

One of my hobby horses is to advise making a Centre Height Gauge, to which tools can be set.

If the tool is on centre height, it should cut well and not produce a pip when facing the end of a bar.

It is easy to make, a good learning exercise, and a saver of time, and frustration in the future.

Somewhere among my albums, there is a picture of the one that I use.

The important thing is ensure the column and base are perpendicular to another. Holding the column in the chuck, and just skimming the base is the easy way of achieving this.

Howard

Failing memory!

Forgot to say that my Centre Height Gauge has two blades. The lower one is there to set the parting tool that is mounted, inverted in the rear toolpost.

Tools in the front toolpost should be set to the underside of the upper blade.

Howard