True Grit

Being inspired by the recent look at diamond stone sharpening, (which is a topic I have returned to on a few occasions already, covering the different aspects of sharpening), I have again raised a few questions I have wanted to answer, and the more answers, the more questions I find to ask!

One thing that seems to be a regular stumbling block is the issue of the grade of the abrasive material.  So many seem to use a similar system of depicting the abrasive properties of the material in question, but then things seem to not quite line up.

Is a 1000 grade waterstone the same as P1000 (ISO system) sandpaper?  And is that the same as 1000 mesh diamond stone?  Or 1000 grit sandpaper using the CAMI grading system? Sort of, no, no, and that is just the start of the confusion.

Without getting into actual definitions, an abrasive is typically small particles that are harder than the substance you want to abrade.  How they are presented to the item is more a matter of choice than if one system is better than another.  They could be a powder which has some oil added and use on top of a flat surface.  Or in a wax and added to a felt wheel.  They could be secured firmly in a permanent base (although only diamond really justifies this).  They could be in a soft matrix and formed into a flat slab, or turned into a slow spinning wheel, and so on.

I’m still not unconvinced (yeah, double negatives) that I’m on the right track by breaking down all the different systems to their micron equivalent.  So perhaps all abrasive systems should be sold using that designation.  Pick up some 100 micron lapping paste to get a flat side, switch over to 75 then 50 micron sandpaper, then use the 35 then 25, then 20 micron diamond whetstones, really develop a mirror with 15 and 10  waterstones, and finally a 5, 2 and 1 micron diamond paste for a deadly edge.  Wonder if I can market that concept?

Oh, and if you wondered what a 3 micron diamond abrasive can do (which is roughly equivalent to a 1 micron friable product) , have a look at the mirror surface of this chisel, sharpened on the DMT “Steel Waterstone”, which is their finest diamond whetstone (also known as the Ex Ex Fine). That’s an awesome finish!  I’m building a list of items that cannot be purchased in Australia that I’d be rather keen to get to try.  This stone is one of them (as is the Forrest Woodworker2 sawblade).

DMT Steel Waterstone

DMT Steel Waterstone

You just don’t realise how big this topic is until you start really delving into it.  Like every topic in woodworking really.

If you are looking for a bible on the subject, start with Lie-Nielsen’s take on the subject from Taunton Press.

nielsenThe guy who comes up with handplanes like this definitely knows his way around the idea of sharpening an edge!

nielsenplane

In the light of this article, I decided to do a quick audit of what sharpening gear I have, and therefore what is still missing from a good system. And because of my push above, I’ll list them in micron order!

Micron Description Speed
269 A60 Grinder 3600RPM
162 Norton Al Oxide 100 3600RPM
68 Triton WetStone 120RPM
20* DMT Ex Coarse Diamond Hand
15* DMT Coarse Diamond Hand
14 Japanese 1000 Waterstone Hand
8* DMT Fine Diamond Hand
3* DMT Ex Fine Diamond Hand
3 Tormek Honing Compound 120RPM
2 Japanese 6000 Waterstone Hand

*I have amended this list in light of recent discussions with the Technical Director for DMT, and the micron size now listed is based on the size of the exposed diamond, which is what is doing the cutting and not the size of the diamond in total (2/3 of which is buried in the Nickle plating).

Not listing sandpaper of course, although it would be valid to include them.  The finest sandpaper I have is P2500, which is around 8 microns.

I also have a Granite Plate, the Alisam and Veritas Mk2 Honing Jig, a bench grinder and the Triton Wetstone Sharpener.

I wouldn’t mind having a diamond whetstone around 15 micron to fill that gap, and around a 2000 waterstone to narrow the jump from 1000 to 6000.

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