Hunter #4 long term test results

[john lucas]

Since I was doing a demo of a platter turned with nothing but Hunter tools I thought it would be interesting for everyone to see my long term test of the cutters. This is a #4 cutter. The first tool I got about 2 years ago or more. I don't use it all the time. Mostly when I'm doing a box interior for the final passes or anytime I have a piece of wood that doesn't want to cut clean. I also bring it out anytime I have someone over to the shop so they can see how it cuts. So it's probably been used quite a bit but not used every day for every cut. In fact it was the one I used in the first Hunter tool demo Oct. 2010 so I had it before that.
Anyway I still can't believe how well it cuts. I had a piece of spalted maple that would not cut clean with my 35 degree detail gouge. I ran this old cutter across it and got a clean cut with no tearout. Then I removed this cutter and used a new one. I could feel the difference, it moved easier, but both left a very clean surface.
Here is a photo of the old cutter next to a new unused cutter so you can see the edge. I discussed this with another turner this weekend and we think the chipped edge is still cutting like a piece of knapped flint. The chipped areas themselves are acting like knives. Don't know if that's true but if you look at that nasty edge it's hard to believe it would do a decent job but it does.

http://www.youtube.com/watch?v=nfp2kvhH6Mo

 

[Richard Jones]

John,

Have you ever sharpened it?

 

[john lucas]

No they cannot be sharpened. I tried once just to see. Not on this cutter but on another one. this one has never been touched. I tried all sorts of abrasives and diamond hones. It just chips the edge. None of them sharpened it.

 

[odie]

We sharpen carbide lathe tools where I work, so it could be done......if one were interested in investing in some expensive sharpening equipment. It's done on a slow speed diamond disc.

If a turner was constantly using carbide tools, it's possible that option might be appealing........ For myself, I don't use the Hunter tools nearly enough to justify the thought of sharpening the carbide cutters.

ooc

 

[john lucas]

Odie I tried several different diamond stones and hones. they did not work.

 

[odie]

Odie I tried several different diamond stones and hones. they did not work.

Howdy John.......

Not sure why you aren't successful in sharpening Hunter carbide cutters. These are straight carbide metal lathe cutters we sharpen at work, and if I were to try and sharpen a Hunter round cutter, I'd assume it would take some sort of rigidly mounted jig with a pivot point for doing the circular shape.

In any case, the Hunter cutters last a long time, and it doesn't seem like it would be a justified expense to get the equipment, and R&D the jig for doing the specific job.......Replacing the cutter seems like the best way to handle it to me!

ooc

 

[john lucas]

Odie I don't know either. I sharpen or at least refresh the edges of my end carbide end mills, router bits one carbide drill bit that I use. I don't have a problem with them. I made a jig to hold to Hunter cutter and mount it on the metal lathe. Then tried all sorts of diamond and abrasive cutters. I thought they might be too course so I ordered a few special abrasive wheels from RioGrande Jewelry supply. The do cut the metal on the cutter but it just keeps chipping kind of like the matrix that holds the carbide is letting go or something. Anyway is just confirmed my suspicion that as long as they do last you might as well just toss them and not try to sharpen.

 

[Jeff Gilfor]

Thanks for the info on the Hunter tool. I've long wondered how well they work, and may very well pick one up. Can you ever have enough tools?

As for sharpening those inserts; the issue is the shape. They are not the flat top ones as in EWT and other scraper type carbide tools. The insert designator is similar (if not the same) as RCMG inserts. These have small positive rake outside diameter (7 degrees?) and a sharp edge inside which forms a toric cup surrounding the screw hole. Sharpening this would require a special jig and/or diamond stone sharpener shaped just for that purpose.

I have sharpened the flat top inserts with good results (as long as there aren't any chips), but can't imagine how you would go about sharpening this type insert. Perhaps a machinist can chime in here.

 

[odie]

Thanks for the info on the Hunter tool. I've long wondered how well they work, and may very well pick one up. Can you ever have enough tools?

As for sharpening those inserts; the issue is the shape. They are not the flat top ones as in EWT and other scraper type carbide tools. The insert designator is similar (if not the same) as RCMG inserts. These have small positive rake outside diameter (7 degrees?) and a sharp edge inside which forms a toric cup surrounding the screw hole. Sharpening this would require a special jig and/or diamond stone sharpener shaped just for that purpose.

I have sharpened the flat top inserts with good results (as long as there aren't any chips), but can't imagine how you would go about sharpening this type insert. Perhaps a machinist can chime in here.

I work in a machine shop, and we sharpen "flat top" carbide tools perhaps a hundred times prior to tossing them. This is the way these tools are designed to be used.

We don't use any round cutters, like the Hunter tool uses.........but, we do use some very similar cutters that are diamond shaped. These have a recessed top surface very similar to the round Hunter inserts. When these diamond shaped cutters become dull, they are tossed out, and not resharpened.

I never really gave this much thought, but it's possible that John Lucas is correct in his assessment that the metal used is not the same as flat carbide stock. I don't know how the Hunter carbide inserts are manufactured, but it's possible they are MIM, or Metal Injection Molded with particles of carbide within a matrix......? Don't know, but that might explain why regular flat carbide can be sharpened, but the inserts are chipping when John tries to resharpen them........

ooc

 

[john lucas]

Or, it could simply be me. When working on the computer I often follow the instructions exaclty and it won't work. My Boss would come over and do exactly the same thing and it works. Sometimes I think I'm that guy with the cloud over his head from the comic series.

 

[Bill Boehme]

It would be necessary to use either cubic boron nitride or diamond with a small enough particle size to give a clean edge if we don't want chipping. But, there are many different types of tungsten carbide and some may not be satisfactory for sharpening regardless of the method