Thread: Hollow grinding, the blade edge and chinks

You do grind to the edge in fact you grind the old edge away to "grind out the chinks" you prevent buring or over heating the steel buy frequently cooling it by dipping in a container of water

Another trick is to put a very shallow crown on the wheel with a wheel dressing tool. This makes the contact point the tangent on that crown and therefore very small. Start at the center of the blade and be very careful as you get to the edges. -Howard

Grind the chink back with the blade square on to the wheel, then re grind the bevel. I always grind right up to and past the bevel. You need to use a coarse wheel and dress the wheel so it isn't glazed. don't be heavy handed.
Mike

Mike is right, but his description may not be clear.

Lee, you are correct in identifying that a thin bevel edge will burn and de-temper if you grind it. So what you need to first do is remove the thin edge - thicken it by grinding back it to a blunt edge. This is what Mike means by "square".

Now regrind the bevel, leaving a 1/16" at the edge unground.

Hopefully this does not confuse you more!

Regards from Perth

Derek

Originally Posted by derekcohen

Now regrind the bevel, leaving a 1/16" at the edge unground.

Thanks - So at this point I hone with whatever - correct?? wet/dry, waterstone etc....

I was not so clear either ..

When I wrote "Now regrind the bevel, leaving a 1/16" at the edge unground", I was referring to a hollow grind.

Once this is done, go to your preferred sharping medium (sandpaper, waterstones, etc)

Regards from Perth

Derek

You can go right to the edge with the right wheel and when you're approaching it, just do one or two passes before setting the chisel aside to cool.

Cooling by dipping into water is said to create microfractures.

The big risk when getting to the edge is that the corners blue. Not enough meat to dissipate the heat in time.

As Mike says, you need a deglazed wheel and a light touch. And patience obviously.

Thanks guys - that explains everything.... I do plan on getting a blu-max wheel, but am having difficulty locating them - any ideas??

Another question - I did put a nice burn on an old chisel today in practice - do I just need to grind some edge back and start again? How much usually, because this burn is on a corner, and projects a good 3-4mm up the (crappy) bevel....

Grind it all away, or learn to heat treat.

And consider Norton 3X (seeded gel) wheels: details

Carroll's Woodcraft sell Blu-max.

Originally Posted by rsser

....
And consider Norton 3X (seeded gel) wheels: details

Carroll's Woodcraft sell Blu-max.

Thanks - will check them out - what is the difference between the 3X and Blu-max - from what I've read the blu-max is softer and wider? Are there more reasons to part with a little extra?
As a novice I need all the help I can, happy to buy the best wheel around!

Any recommendations for the other wheel? should I leave a stock grey wheel on or replace it also??? Keen to hear what others have done....

It's a while since I used a Blu-Max. It's claim to fame is the honeycomb structure that helps it run cool, but I found the bond fairly hard. J rated. The plus is you have 40mm width.

Davey's 3X wheels are K bond so a little harder but the 46# cuts quite quickly and cleanly IME.

That said, a coarse white wheel will do the job well enough with patience and cleaning. If you only have a few tools to rehab it will serve.

Keep the grey wheel for rough work. Most folk say it's not good enough for high carbon steel.

HTH

On the right track now I hope - just had my Norton 46-grit SG blue wheel delivered - hats off to the sandpaperman.... (36hr from order to delivery - well done!)
Thanks for the advice Ern.

Lee

Good stuff.

Now I haven't tried this yet with this wheel, but I'd follow the advice of another forum member re cleaning the wheel and go in hard with a carborundum stick (while trying to maintain a flat and square face).

My impression so far is that using a diamond T-bar to unclog the wheel effectively reduces the grit rating to something like that of the diamond, which is finer than I want.