Wednesday, 15 March 2017

Sharpening with diamond sharpening plates

Over the years I have gone through many different sharpening techniques, oilstones, waterstones, sandpaper on a granite plate, using honing guides, free etc. All have their own advantages and disadvantages.
Recently I have become a fan of Paul Sellers and bought his recent book of 2016 "Essential Woodworking Hand Tools" and its associated DVD collection.
In the book and DVDs Paul shows the system he has developed over the years of using 3 diamond plates of various grits to hone plane irons and chisels. The honing is done with car glass cleaner. He is very specific about this so who am I to argue.

Final polishing is done with a leather strop coated with green honing compound.
Diamond Plate Holder

I decided to adopt Paul's system so taking advice from him bought a set of three diamond plates. I had the option of the expensive DMT Dia-Sharp plates or the still expensive EZY-Lap plates. He recommended the EZY-Lap plates as there was no appreciable difference in performance from the two decades of experience he gained from using both manufacturers.

The plate size is 3" x 8" which is a decent size to hone most common woodworking hand tools. Paul recommends using a piece of wood or plywood no thinner than 1/2" but preferably 3/4" thick.

Plate holder manufacture.

I had some 18mm marine plywood in stock so cut a piece 11" x 9.1/2"

Plate holder dimensions

Using a knife and straight edge I marked out the 8" x 3" pockets. Then the pockets were cut to depth using a powered router taping a plywood straight guide to get a straight line. The centre was hogged out with the router. Finally finishing the depth with a hand held manual router plane. This was just to clean up the bottom of each pocket.

A ledger strip of oak was glued and screwed to the bottom face of the plywood. I used screws as it is easy in operation to tear the face veneer off from ply. You can either do as I have done or cut a dado into the base and glue the strip in.

The pockets were sized to be a tight fit on each diamond plate. A couple of release holes could be bored into each pocket to allow later removal of the plates. The whole board was given a couple of coats of General Finishes Exterior 450 to protect from moisture.

In use.

Clamping the holder into the bench vise puts the plates at a reasonable height to start honing.
I use the Veritas MKII honing guides (both the regular one and the narrow blade one) to hone my edge cutters.
I arranged each plate the same way Paul does: "Coarse" on the left, "Fine" in the centre and "Extra Fine" on the right. 

First off I flattened the base of my Lee Nielsen #4 bronze. This only took a few minutes as it was already very flat. Then I worked on the A1 blade in the #4. Even with diamond plates this took some time to do. The resulting finish wasn't mirror finish from the extra fine. I ran it over my leather strop with green honing compound applied and it soon became mirror like.

Next using the regular MK2 honing guide I reformed the primary bevel to 25 degrees. Again this took some time to do but was so much easier than using a waterstone or sandpaper (Scary Sharp). The strop again gave a mirror finish.
I applied a microbevel of 26 degrees to the tip and refitted it to the plane.


After adjusting the plane I was able to produce very fine shavings on a mahogany test piece. The resulting surface finish was superb as I expect from a premium plane sharpened with diamonds.

I then did the same on a Acorn by Stanley plane (1930s vintage "second quality" Stanley plane made in Sheffield but still better than some modern planes!); flattening the sole, flattening the frog and honing the blade. This blade is just the regular thin O2 blade and was very easy to do. This took a mater of minutes to flatten the backside and hone the bevel. The diamond cuts so quickly.
Reassembling the plane, adjusting the frog to close down the throat gap and fitting the freshly sharpened blade.

The results from fettling this old plane was astonishing. Not quite the premium quality from the Lee Nielsen but still more than acceptable for this old beater plane. I have had this plane for 30 years and it was ok when sharpening with other methods. Now it is superb with diamond.

I worked through all my LN A1 chisels and all the vintage Sheffield O2 chisels and achieved a fine mirror finish on each. As ever the harder A1 were slower to get sharp but the diamond made short work of the regular oil hardened steel.


Early days so far but initial indications seem to show that sharpening with diamond is quick, less messy and easy to do.
The diamond plates don't need flattening unlike oilstones or waterstones, no furrows are ploughed so sharpening tools should be quicker. Go to the plates, hone and get back to work.

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