It is a sinking feeling when you take a look at the cutting edge of your knife, and see a chip in it. But it happens. Sometimes completely regrinding the bevel is the best solution, sometimes not. Below are some options to consider, depending on the nature, size and location of the chip, how the blade is used, and what your sharpening set-up is.
1) Live with it. This is often a good solution for small chips. It will make a weird little ridge in the leather (or other material), and you will have to go back over it with a different part of the knife, like removing the ridge between multiple passes of a double edge razor blade paring machine. As you resharpen the blade it will get smaller each time.
2) For large chips, alter the cutting angle around the chip so the blade can still function. The example above shows a huge chip, and fixing it by regrinding the bevel would have removed most of the knife. The previous owner cleverly fixed it by putting an edge on the large chip. This blade still works quite well for hacking small branches. In fact, I kind of like having the notched higher bevel area. Of course, this depends on what type and size of blade you have and how you use it.
3) Regrind to the original bevel using the coarsest diamond stone you can find, at least a 220 US grit. Even though I have belt grinders, for a narrow chisel like this one, it is easier to control working by hand on a diamond stone. It really doesn’t take that long. And you can skip your HIIT tomorrow.
4) Regrind to the original using a belt sander, belt grinder, Tormek, or a stone grinder. If the blade is wide or thick, and the damage severe, a complete regrind might be the best option. Obviously, it is quicker to have a machine do the work, rather than your arms. I highly recommend the Kalamazoo 1 x 42 belt sander if you are in the market for a new one. I’ve had one for over 20 years, and sometimes during workshops it has run almost continuously for a couple of days.
5) To fix a chipped corner, if the width of the blade is not of that much importance to you, it is often easier to reduce the it rather than regrind the bevel, like on the chisel above. This can ruin a rare or important tool, though. Often the entire width does not need to be reground, as the image above shows, but it can be rounded towards the tip. This can be done by hand on a diamond stone or on a machine grinder. Sometimes only a small amount of the blade on the bevel needs to be ground, sometimes the entire length. In this case, it was an inexpensive Buck chisel that I use for crude chopping, and has little value otherwise.
6) If the tip or corner is chipped (which is very common) it can be easier to round it. Some prefer to have rounded tips on leather paring knives and other knives anyway. Think carefully if you want to keep the original bevel angle, or raise it slightly as in the above example. The above chip could also be fixed by reducing the width of the knife on the left side of the image.
In the 21st century, bookbinders are understandably nervous concerning the continued availability of essential machinery and replacement parts. Many of the board shears and guillotines we use on a daily basis are more than a hundred years old. This equipment not only needs to be maintained, but periodically their blades need to be resharpened or replaced. The last New York City grinding service, Ace, moved to New Jersey a number of years ago, priced out of Soho.
I support Ace by using their services. I also collect and preserve bits of history associated with these types of industries, such as this desk blotter ephemera I scored over the past weekend. This is the second bookbinding related desk blotter I’ve found in the past month, a little unusual, though synchronous finds are not uncommon in dedicated flea market and antique mall exploration.
The Wapakoneta Co. was sold in 2009, but is still making knives and industrial cutting products. But as the numbers of newspapers, books, and other paper based products continues to shrink, what will happen to these vital ancillary trades — like board shear blade making and resharpening — that hand binders and conservation labs rely on?
One of the most common mistakes in sharpening is to allow your stone or film to glaze over. This significantly increases sharpening time, since the knife is not abraded by the grit, but is burnished against embedded steel. Not using enough lubricant is a common reason for this, as is not regularly cleaning your substrate. Depending on the size of the grit, either a microfiber rag or a white vinyl eraser works best.
My sharpening setup, above, consists of a bright swing arm lamp mounted directly above a cork faced workbench (PSA cork shelf liner), a microfiber rag, a large squeeze bottle of water, and the Peachey Sharpening System. I find it more comfortable to sharpen at a lower height, around 34 inches, than my regular bookbinding workbench. Many hundreds of knives have been sharpened here!
The microfiber rag is perfect for cleaning larger grit 3M micro-finishing film, from 80 to around 15 microns. This rag was white when I purchased it, a testament to how well it picks up and retains small metal particles. I also use it to clean off the knife between grits in order to examine the scratch patterns.
For 5 micron and smaller grits, a white vinyl eraser works wonders. Pictured above is the neon lime green 1 micron film, which glazes quite easily. Using the eraser on coarser grits eats it up too quickly.
Of course, over time, the abrasive will wear to the point nothing much happens, and you will need to replace it. I can usually sharpen ten knives or so on one piece of 2 x 11 inch film.
By using plenty of water as a lubricant, and cleaning the film after each use, the effective working life of finishing film will be prolonged.