How Sharp is Sharp Enough?

[GIPPER]

After sharpening my tools, checking with the fingernail and hair test, they appear to be sharp. However, I found that carving "with-the-grain" is good, but carving "cross-grain" the tool is more or less "tearing" the fibers instead of cutting them.  Shouldn't the chisel be sharp enough to cut cross-grain as well as it cuts with-the-grain?  I am testing this using Mahogany Wood.  Gipper

[mGuitars]

What angle are you sharpening to?  The lower the angle, the easier it is to cut across the grain. 

[GIPPER]

Most carving chisels are 25 degrees.  A couple gouges are at 40 degrees.  Gipper

[Jeff Farris]

Torn grain = not sharp.

Look at the steel. Is it fully reflective, just like a mirror? If no, then you didn't spend enough time with the stone grader when moving from fast cut to fine cut. Is the burr still present? If yes, then you either didn't spend enough time on the honing wheel, had too little compound on the wheel or worked with the angle too flat. If the surface is fully reflective, and the burr is worked off, yet it still isn't sharp, you have honed with the tool at too steep an angle to the honing wheel and rounded over the edge.

Since you say it will catch your nail, I'm going with "A" as my guess. Your edge is saw-toothed from inadequate fine grinding.

[GIPPER]

Thanks Jeff F.
I spent about 15 to 30 seconds with the grader from course to fine grit and using moderate pressure.  I can see faint grind marks on the bevel surface.  It's "shiny" but not "mirror" shiny.  After honing, I can still see a little grind marks and surface still is not "mirror finish".  So perhaps I'm not spending enough time with the Grader.  What do you think?  Gipper

[Jeff Farris]

Keep at the stone grader until the surface of the grindstone feels like a piece of wet glass. That is your problem. Your edge is saw-toothed. The honing wheel can't remove the scratches from the fast cutting action. The intermediate step is critical to a truly razor sharp edge.

[GIPPER]

This post could easily be re-titled to "How Long is Long Enough?".

I re-sharpened two carving chisels, taking longer regrading the wheel with the Grader to fine grit.  I timed it for two minutes this time instead of the 30 seconds as before.  It worked much better but still not quite "mirror-finish".  I could still see very faint grind marks on some of the bevel surface.  And its true that honing did not get rid of them.  So I'll do it again.  Maybe the "third time charm" will do the trick.  This time, I'll try four minutes.  However, I did note that the tool was much sharper than the first try.  That's encouraging.

Oh, BTW.  When preparing for the honing step, don't forget to change the Cam setting on the WM-200 to 220mm wheel diameter.  It helps!!

It is said that Experts are those who have made all the mistakes.  If that's true, then I'm well on my way to becoming an Expert.  LOL.  Thanks for all the help.  Gipper

[GIPPER]

I recently had an experienced furniture-maker and turner tell me that "turning tools" needn't be sharpened more than with a 60 to 80 grit stone.  Other opinions appreciated.  Gipper

[Ken S]

I recently had an experienced furniture-maker and turner tell me that "turning tools" needn't be sharpened more than with a 60 to 80 grit stone.  Other opinions appreciated.  Gipper

Gipper, I have heard the same thing from another expert (who teaches turning).  I would suggest trying both ways with some practice turning.......My gut tells me sharpen is better, or should at least stay sharp longer.  Give it a try.

Ken

[Jeff Farris]

I recently had an experienced furniture-maker and turner tell me that "turning tools" needn't be sharpened more than with a 60 to 80 grit stone.  Other opinions appreciated.  Gipper

In 19 years of selling Tormek, I have heard this countless times. In all those years, I have not once failed to get an awestruck look on the face of the "experienced turner" when they turn with a tool I've sharpened.

Here's why turners turn with a ragged edge.  No edge will hold up indefinitely to the heat and abrasion of a spinning piece of wood. Before Tormek, the time investment necessary to get a polished edge on a complicated shape like a fingernail grind far exceeded the time saved by having a superior edge. In other words, with slips and stones and hones, it just isn't worth it.

But, if you use the jigs properly, you can produce a super-fine finish on your tool in less time than a dry grinder can create his ragged edge tool. The Tormek edge will produce a superior finish on your work plece, need sharpening much less often, and less steel will be removed with each sharpening. Win. Win. Win.

[Ken S]

Gipper,

These are only my thoughts and opinions, with no research to support them.  I believe every craft has its myths and legends.  They usually have an original foundation of truth, but often can become distorted in the dreams of enthusiastic hobbyists.  These myths often revolve around the volume of work we hope to produce.

Before I bought my Tormek, I spend a lot of time modifying my Omnijig (dovetail router jig).  The old myth there was about the guys who "make forty drawers in an hour".  Impressive.  However, in the real home shop world, few of us have made more than forty drawers over a lifetime.

The turning myth goes back to the bodgers.  They were itinerant turners who worked outside in England a century or more ago.  They turned out thousands of parts for chairs.  (Just like today's trim carpenters who "leave the nail holes for the painter", the bodgers did not finish the chair rungs.)

Jeff makes an excellent case for more finished edges.  Would we rather spend our time making our turning tools razor sharp or smoothing the turned pieces because of ragged edges?

To Gipper and Jeff: Excellent posts.  Let's shed the light of day on some of these old myths and move forward.

Ken