A few days ago I wrote about trying to sharpen Hunter tungsten carbide tips. My attempts were not very successful. The tips are cupped, and I tried honing the sides and also grinding the groove in the top. I managed to improve the very blunt cutter but not to produce a ‘sharp’ edge. I think though that if the tip had been used on ordinary wood and not the abrasive stuff I am sometimes faced with, and had just lost its keenness, honing its side bevel in the lathe as I described would have been worthwhile.
I wanted to use the tip on some MDF today and found that even after my efforts it is really too blunt for freehand cutting. It makes hard work of it.
It’s time to write this tip off, at least in its original form. Other manufacturers offer flat carbide tips, which have a different cutting action. People find them very effective, as long as the right grade of carbide is used. For example, opinions of the Easywood tools are very favourable (I haven’t tried them myself). So I decided to convert the Hunter tip to a flat top. Better than just discarding it, there is plenty of carbide left, and they aren’t cheap.
I simply rubbed the tip on a coarse and then a fine diamond hone until the edge felt sharp and smooth. A little of the centre was also honed away in the process, but it went back in the Hercules tool with no problem. Back to the MDF!
I immediately realised that the forward tilt of the tip mounting gave too much negative rake for scraping with a flat tip. Lowering the handle until the tip was horizontal was much better. It cut even better with the tool tilted sideways and bevel rubbing.
So with very little effort I have a round carbide tip that could be used in any homemade cutter bar. Not as good as new, but too good to throw away.
Have you tried sharpening these cutters? Let me know!