Dear Mr. Sellers
I am about to work my way through your course, I want to start with sharpening. I recently discovered that my new chisels, although of good quality, needed to be lapped. I turned to my Norton water stones, only to discovered that they needed to be flattened. I then turned to my Norton flattening stone only to discover that it was crowned (not dished) and needed to be flattened. So now I need to buy a diamond stone to flatten the flattening stone to flatten the water stones to flatten the chisel! I therefore appreciate your logic of eliminating the ‘middle men’ and flattening the chisel directly on the diamond stone.
However, before I purchase the diamond stones, I have a question concerning the gradation of the stones which I hope you will be kind enough to answer.
I currently use three water stones 1000, 4000 and 8000 grits to grind, hone and polish. When looking at what DMT (the maker of the stones available from Lee Valley) offers, a trio of 600, 1200 and 8000 seemed appropriate though I wondered about the jump from 1200 to 8000.
You use 250, then 800 and 1200 grit stones to grind and hone, followed by 15000 grit stropping to polish. DMT recommends 325, 600 and 8000 stone followed by polishing with 1 micron paste. Your gradation (and DMT’s) is quite different from what I expected. Can you explain the reason for your choice and whether the medium is a critical issue. In other words, if you were to use water stones, would choose a different mix.
I look forward to your response and getting your course off to a sharp start!
Firstly, I have shortened your letter just a little to reduce the lead in for the readers and to keep your name private. Here we go:
Uneven surfaces on sharpening stones is most common and in the ones I have tested, high end ones included, the problem is common to almost all stones. This is an extreme and rare exception in better quality diamond plates. Cheap sharpening plates are rarely flat and all other stones never stay flat because that is impossible. Especially is this so with self fracturing water stones, which is the main advantage of good diamond plates. That being the case I stay with diamonds alone because they never let me down. I have noticed of late a hybridizing of abrasives. I think that this is often more silly than practical. I am not sure why people complicate things so. perhaps it’s to supposedly create their ”own methods.” I find that it’s this that confuses the whole issue of sharpening and prolongs what should be short, quick, simple and effective. Better instead to simplify rather than merely make a name for ourselves.
A few years ago, for about three decades, all the guru woodworking writers were advocating Japanese water stones. Everyone went in that direction and began rejecting other types of natural and man-made stones and started buying stones that, well, wore out. Great stuff for catalogue companies and salesmen who were also offering the same advice for some reason I assure you. Remember that many of our present day “experts” became gurus through slick sales talk and we have seen them go through the gamut of selling planes, selling techniques and selling sharpening stones or plates. Many of them have gone from selling water stones to selling diamond plates, diamond paste and tons of other stuff. One company, Trend, sells a bottle of diamond lapping fluid for an unbelievable £7.50 and states that WD40 is too thick and that doing so “results in your tool skating over the diamond surface.” This is not true and therefore in my book that makes it a lie I suppose. That said I don’t advocate WD40 because it is primarily composed of hydrocarbons. I generally find glass cleaner, not window cleaner, the kind we use for cars, the best treatment and instead of paying £7.50 per 100ml I can buy 500ml for under £1 from any Pound stretcher store and it works as well if not better. Watch out for the snake oil!!!
By now you will realize that I have no time left for water stones because of their intrinsic propensity to disintegrate and end up hollow. Using another stone to flatten it depends on that stone being flat. Though it may start out flat, it cannot stay flat, so we have a built in problem all around. Forget water stones and get diamonds. How did that song go? Diamonds are a man’s best friend.” It’s a good idea to progress rapidly to diamond plates and better quality ones such as EZE Lap or DMT.
When it comes to particle size as you rightly say I have used 250, 800 and 1,200. This in fact quite arbitrary really because the particulate fractures and becomes finer as you work the stones. What starts out as coarse 250 ends up being much finer the more I use it. Eventually I replace the coarse because of this. It would actually be hard to say what the particle size is on any stone once they have been used for a few weeks. So, instead of become overtly concerned about grit size I have found course fine and superfine from EZE Lap works well and has worked well for me for over a decade. Nothing more philosophical than that really. I will say that I find 8,000 grit a huge jump and would tend to stay with jumping with the buffing compound rather than diamonds. The finer the grit the greater the propensity to surface clog. You don’t get that with compound and a strop or wood.
Not scientific at all, but you see the results as I work. People have become overtly obsessed with sharpening to fine levels that are impractical for real woodworking in general. That’s fine if the intension is to sharpen and not work wood. Many such people lose sight of the fact the wood itself is abrasive and so what starts out at 15,000 or 20,000 becomes reduced to a few hundred in the first few strokes anyway. That’s the edge that becomes long lasting, not 20,000.