Tuesday, 21 December 2010

Sharpening carving knives

Well it's my last post of the year and, following on from my post illustrating my sharpening block, I thought I'd say a few words about how I sharpen my knives. I have all sorts of stones, grinders, jigs and the rest of it but for most sharpening tasks a bit of cheap, simple and non-powered kit is more than adequate. There is loads of information on the web about sharpening including Youtube tutorials, so I'm not going to add too much here- just convey my system.
You may be able to make out from the previous post that I have made blocks of different grits by sticking wet and dry onto offcut blocks of MDF and plywood. The finest grades I got from here in America and are adhesive backed. They are microfinishing film that were originally developed for body finishing in the automotive industry. I have them in 15 micron, 5 micron and 0.3 micron. You can get it now from here.
To use the blocks I sit them an a piece of anti-slip router matting, and lubricate the surface with mineral oil (baby oil is just perfumed mineral oil)- this floats away the metal fines and stops the abrasive surface clogging.

This is how the knife should be held for a right handed person, note the fingertips of the left hand are pressing the bevel down flat on the abrasive surface and the left thumb interlocks the hands in unity. The elbows should be locked and the upper arms held against the body so the stroke is driven by the legs. As you can see from this picture, we can only sharpen the straight part of the blade with the handle canted at the bevel angle:

So the handle has to be raised slightly at the end of the stroke to maintain an even bevel right to the tip. This can be quite tricky but comes with a bit of practice-just remember to keep the whole of the bevel in contact with the abrasive.

As you work through the abrasive grits getting finer and finer, you should start counting the number of strokes performed on each side of the bevel so that the edge remains central and an excessive wire edge is not formed. As you get to the really fine grits reduce the number of strokes on each side before flipping over and work only in the direction that has the cutting edge trailing. Also resist the temptation to roll the blade over on the cutting edge to avoid rounding it over- rather, lift off the surface before flipping.
After sharpening the blade on the abrasive blocks I hone my blades with a flat offcut block smeared with car body polish (which of course is super fine abrasive in a lubricating suspension). The grip is exactly the same. Unless the cutting edge gets really neglected and rounded over or picks up a ding, this is all that is needed to be done whilst carving to maintain a super sharp edge.
With hook knives the principle of keeping the bevel flat on the block surface is exactly the same. If you need to flatten the inside of the edge you can wrap some abrasive round a piece of dowel:

but the bevel is on the outside so this is where we need to work most.This is a compound movement with the bevel flat on the block and, starting from the tip, the blade is rolled towards the handle, whilst at the same time drawing the blade along the block-edge trailing. I have tried to photograph a sequence to illustrate this:-

As I said not much point in going into too much detail but hopefully this may be of some use to beginners.
Last project of the year is a chopping block and coasters for my colleague. He is converting a barn incorporating exposed green oak trusses so I thought I'd make him something to echo this. I guess oak would not be an automatic choice for a chopping block with its high tanin content so it will be interesting to see how it fares with use. It is treated with cold-pressed Linseed oil. The coasters are Burr Oak. I will bore a hole in the centre of these so they can be skewered on a stand with a central pole.

I am currently awaiting delivery of some adhesive backed thin cork matting to stick to the bottom of the coasters to make them anti slip and non abrasive to table surfaces. Similar to the commercial coaster in the picture. A good use of offcuts I reckon, and hopefully they'll be gratefully received.

And finally, I filtered my Sloe Gin this week and it is proving very popular, Slainte!!!!!!!!!

Merry Christmas and a Happy and Prosperous New Year, John.


  1. Hi John ,found your blog by accident its very interesting, you craft many nice things:)

  2. Thanks for the support Brian. Once I've finished our fitted bedroom I'm hoping to be more productive in 2011- I've got loads of ideas for craft projects I'd like to realise so hopefully the results will appear on here.
    Thanks again, John