Grinding tool bits

[DalboyParticipant @dalboy]

Posted by John Reese on 02/10/2021 00:52:53:

Posted by Derek Lane on 01/10/2021 13:44:28:

I have just sharpened my first hss blank I followed This Old Tony on u tube he does his very much like Mr Crispin video, I have just used it to turn some Ali with great results and some great chip breaking rather than long strings.

Congratulations. It is very difficult to create a tool that will break chips in wrought aluminum.

From what I have learnt I was expecting the long twirls so how I got chips I don't know just luck will try later and see if I can reproduce them.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Steve355 on 01/10/2021 10:19:58:

…

2) when grinding a plane blade, of course the grinding wheel leaves a small amount of curvature. But I just hone this off on the sharpening stone, through several levels of grit and then strop it for a “scary sharp” finish. But on the lathe bit, the area I’d need to hone is much bigger, and I don’t have a nice sharpening jig to keep it perfectly flat against the stone.

…

Steve mentions honing, which I've never done to an HSS cutter intended for use on metal. My logic, which could be wrong, is that metal cutters don't need to be super-sharp because they wedge rather than cut. Note in the picture below, the tool tip isn't in contact with the metal.

The wedging action is taken to the extreme with most carbide inserts which are on the blunt side. A sharp edge is only needed to start a cut or to remove tiny amounts of metal. As a very sharp edge is easily damaged and metal is hard, sharp edges are easily damaged.

It's still important that metal cutters have an edge, because being too blunt is a disaster. Never let cutting tools rub!

In my mind, metal cutting is rather different to slicing through soft fibrous materials like wood where being razor-sharp is a major advantage. I don't see any value in honing lathe tools. Am I right?

Dave

[Grindstone CowboyParticipant @grindstonecowboy]

Posted by SillyOldDuffer on 02/10/2021 09:30:05:

….I don't see any value in honing lathe tools. Am I right?

Dave

Well, from what little I know, and from personal experience, I've had better results with HSS when it's honed.

Rob

[DiogenesIIParticipant @diogenesii]

Dave, er, isn't that an illustration of undesirable cutting conditions caused by Build-Up Edge deposits?

[IanTParticipant @iant]

Posted by Grindstone Cowboy on 02/10/2021 09:36:15:

Posted by SillyOldDuffer on 02/10/2021 09:30:05:

….I don't see any value in honing lathe tools. Am I right?

Dave

Well, from what little I know, and from personal experience, I've had better results with HSS when it's honed.

Rob

Like many things, it depends on what you are going to use the tool for and to some extent the size of work and material type. I use a diamond tangential tool for a fair bit on my ferrous work and have found no need to hone, apart to slightly round the tip for longevity. If I intended to use a tool for roughing, I wouldn't bother to hone then either.

But on the occasions I need a really sharp tool (fine finish, bronzes, smaller parts) then I certainly do hone and it's very easy and quick to do if you start by using the front of the grinding wheel and already have a concave face. Then you can simply hone the top edge (using the bottom as a guide) – you don't need to hone the entire face, just the cutting edge.

Here's a shaper finishing tool that has been honed (the bright edges) the 'grey' area has been ground on the front of the wheel and you can still see the grinding marks (the ground face only looks dull because of the angle I'm holding it at). The same principle can be applied to any single point cutting tool and the smaller the work or finer the finish required – the more often I do it.

Regards,

IanT

[thaiguzziParticipant @thaiguzzi]

If the OP is getting a great price on buying long lengths of HSS (20cms 8" – not unheard of out here), it is very very easy to cut it in half with a 4-5" angle grinder and a 1-1.5mm wide cutting disc fitted.

Felt tip marker pen the middle, put it in the vise tight and have at it.

2 x 4" pieces with 4 useable ends.

As others have noted, a white wheel in your d/e bench grinder is the way to go, but prior to that, i don't, but you can, use your angle grinder for preliminary shaping.

I note that some of the old post WW II ME masters were not averse to using an HSS tool finished on a round wheel, which makes the angles generally easier to finish hone.

[DalboyParticipant @dalboy]

Posted by John Reese on 02/10/2021 00:52:53:

Posted by Derek Lane on 01/10/2021 13:44:28:

I have just sharpened my first hss blank I followed This Old Tony on u tube he does his very much like Mr Crispin video, I have just used it to turn some Ali with great results and some great chip breaking rather than long strings.

Congratulations. It is very difficult to create a tool that will break chips in wrought aluminum.

Tried again today all the same settings and feeds but this time got the long strings just lucky the first time it was 6082 ali

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