Chip Fix: Seven Approaches to Repairing a Damaged Knife Edge

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.

A small chip like this will work itself out after a few resharpenings.
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.
Hand forged Japanese gardening tool with the chip reground to function.
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.
The bevel edge of a chisel in very poor shape from abuse. A good candidate to regrind.
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.
The bevel angle of this chisel was ground too shallow for how it was used, and the entire cutting edge rolled off on the left side. A good candidate to regrind.
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.
The width of this chisel was reduced (on the top) to get rid of a chip at the top corner.
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.
A tip chip.
Solution: a new rounded tip.
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.
Regrinding a knife back to the original bevel angle.

Reflections on Five Essential Bookbinding Tools. Broken Chocolate and Shards of Glass: A Brief History of the Olfa Knife.

Over the past eighteen posts, a number of bookbinders and conservators responded to the question, “What are the five most essential bookbinding tools, and why?

The responses were interesting for a number of reasons: how the authors interpreted the question, their actual choices, and their reasoning. Some took a desert island approach, some took the “what would I grab if my studio was on fire” approach, some based their decision on frequency of use, some discussed intricacies of their handmade tools, and some recorded provenance of heirloom tools they were gifted.

I discovered new tools myself (especially thanks for the splinter forceps Jim and your beautiful curved needles Allessandro!) and was pleased that my A2 paring knife and delrin folder were frequently mentioned.

Two ancient tools, a bone folder and a needle, topped the most cited list. John C. Whittaker, in the book “Flintknapping: Making and Understanding Stone Tools” speculates that Homo hablis likely used bone tools around 2 million years ago to make arrowheads and other stone tools. The needle dates to around 50,000 years ago.

The third most commonly mentioned tool is a relative baby. Yoshino Okada invented the Olfa snap-off blade knife in 1956. He lived through the occupation of Japan by the United States in WW2, and later remembered American GIs giving him chocolate bars which could be broken into pieces.  Working for a printing company, he grew tired of not having a sharp knife always at hand. Inspiration struck when he was looking at the sharp shards of a broken glass, the memory of the chocolate resurfaced, and the concept for a snap-off blade was born. At least according to official company lore.

The Olfa name has become generic for any snap-off blade. Like other brands that have become generic — Google, Popsicle, Xerox, Kleenex, Bubble Wrap, Dumpster — it is a sign of outsized influence and dominance in a market. Once a brand name reaches such market penetration, even if it is trademarked, it is no longer enforceable. Most bookbinders and conservators, myself included, use an Olfa daily.

An early Olfa knife. https://www.olfa.co.jp/en/birth_of_ofla_cutter/index.html

The image above is one of the earliest extant Olfa knives. The genius of the snap-off blade design is that the breaking score line does not extend into the blade bevel, so that when it breaks it naturally forms a sharp cutting tip. The Olfa Silver is a direct decedent of this early handle design. The blade lock was not yet invented, nor the blade breaking end piece. Yet it is a clever piece of bent sheet metal engineering.

The original Olfa design was not patented, hence the plethora knockoffs that persist to today. I’d guess the reason it wasn’t is the same reason a number of new inventions are never patented today: patents now are comparatively expensive, around $13,000. It is a huge leap of faith for a novice inventor secure one, and then have additional expense to deal with infringements. At that time, Okada had no idea if his knife would be a success or not.

Once the Olfa company was established, it patented a number of later inventions. The most well known of these is a rotary cutter still extensively used by fabric crafters.

An early 20th c. wallpaper cutter in my collection. Although the blade can roll, it is used locked in stationary position. Rotating it allows new cutting edges to be exposed.

Of course, everything has antecedents. I have a rotary wallpaper knife in my collection from the early 20th century, though I think it is used with the blade locked and not rolling. It is unmarked and not patented, beautifully made and the entire knife balances precisely on one finger. Rolling cigar cutters, pizza cutters, pie crimpers all have a similar morphology and predate the rolling Olfa.

The company was originally named “Olha”which in Japanese “Ol” means to break, and “Ha” means blade. There was some confusion in French, so the name was changed to Olfa. The yellow color scheme was introduced in 1967, and intended to reference both safety and the familiarity, with the yellow evoking the warmth of an egg yolk color. Even some of the knock-offs use a similar color.

A number of the Olfa style knives I use. Using a variety of handle shapes is much less tiring on your hands if you have a lot of cutting.

I’m a bit of an Olfa collector, and the newest handle, and one of the nicest IMHO, it the the PA-2, which stores and automatically loads five complete blades in the handle, which is more than enough for onsite work or an extended workshop. The thickness is just a bit more than the Model 300. It has a amazingly smooth action, and so far has resisted blade pull out even in thick and dense materials. The blade support at the tip is beefier than other models.

Limited edition all black PA-2. Purchased from Japan. Kireina!

Some object, not unreasonably, that using an Olfa is wasteful since the blade is not resharpened, but discarded. It that bothers you, genuine Olfa blade steel is good quality, and can be stropped back into shape once it starts to dull.

Pay attention to what you eat and break!

 

New Tool for Sale: Micro Knife

Micro knife slightly extended in its mechanical pencil holder.
Micro knife fully extended.

This is the smallest knife available on the conservation market, with a .9mm width.  The M2 steel blade retracts into a standard supplied mechanical pencil handle, so it can be retracted when not in use. The blade can be extended to about 20mm to reach into recessed areas. It has a double bevel, and can be used for cutting complex fills, working under magnification, miniature bookbinding, anywhere you need to make precise small cuts. Can be resharpened and stropped. Or the blade could be dulled to use as a micro spatula. The M2 steel blade is hardened to Rc 65. Just don’t mistake it for a pencil!

Order a .9mm Micro Knife with retractable mechanical pencil handle here for $35.00.

Cutting tight curves in Japanese tissue.