Why can a knife edge break at all and what leads to this? Quite understandable, but not always an obvious reason - under different circumstances, the knife tip, which is quite thin due to the design of the blade itself, is subjected to a force or pressure that exceeds the physical parameters of the steel in this area of the blade.
If the strength and elasticity properties of the steel in this area are exceeded, the knife blade will inevitably get damaged. A blade with a high hardness level will break and a softer blade will bend over. Here is an example for better understanding. Accidentally damaging or breaking off the tip of a thin and flexible fillet knife is hardly realistic. When using the knife as a pry bar, you get a great chance of damaging even a fairly strong blade of any knife in the form of a broken-off tip.
It is important to note that any damage, especially if it is significant, will make it impossible to return the knife blade to its former shape. After mending, the blade will inevitably change its shape. With minor damage, the correction may be completely unnoticeable.
You can select ways to repair the knife according to the design of the blade, and a great deal will depend on the length of the broken tip and the blade shape. There are several predominant knife types among all possible variants that you can find in a store. Certainly not each of these knives is at risk of tip damage, but sales statistics are a stubborn thing.
Thus, among the entire range of knives, knives with blades that have the following tip shape have an increased breakage risk:
Photo 1. Normal (Standard) Blade
Photo 2. Drop Point Blade
Photo 3. 1. Clip Point Blade
Photo 3.2. Clip Point Blade
Photo 4. Sheepfoot Blade
Photo 5. Wharncliffe Blade
Photo 6. Trailing Point Blade
Photo 7.1. Dagger Blade
Photo 7.2. Dagger Blade
Photo 8. Spear Point Blade
Aside from folding and fixed knives for various purposes, most kitchen knives fit primarily into the category of plain edge or downward sloping blade spine groups.
Some of them belong to the type of blades with a spine rising upwards - trailing point, with a spine sloping towards the tip - sheepfoot point, and some belong to the type of wharncliffe.
In general, the weakest part of any blade will be its thinnest and narrowest part - the tip. That said, the thinner the spine, the more likely it is that the point will break or get damaged if used the wrong way. Wrong way refers to the use of the blade for other than its intended purpose. The knives that are used the most, especially daily, are the ones that are at the highest risk of being damaged. The more often you use the knife, the more likely you are to damage it. However, this is not a pattern at all.
The images of different types of blade points mentioned in this article are here for reference and only give a general idea. In reality, the knife specifications may vary. Due to this, further we will only mention general methods for repairing broken knife tips.
If you want to know how to solve this issue, here are two common approaches:
The first approach includes a complete resharpening of the blade, which, is the most proper, but more expensive way.
At the initial stage, you have to reprofile the knife blade to the desired shape, then form new bevels and only after that you can create a new cutting edge. From a technical perspective, the complexity of some knife bevel types makes it impossible to follow this method to repair them. This method also has a risk of tempering the steel, if you get the blade overheated in the process. At the same time, not every craftsman will take on such work.
The second method involves partial repair of a knife blade and seems easier and cheaper at first, but hides some details that you need to pay attention to. These methods do not necessarily rule each other out.
Depending on the blade design and damage type, there are multiple technical solutions that you can follow to repair a broken knife tip:
It makes sense to use one or both methods at once for some blades. At the same time, you will need to develop an individual approach for each specific case, since no two damages are alike.
There are two common types of tip breakage: when it breaks closer to the spine, and another closer to the cutting edge. The latter is more likely to occur since the cutting edge is much thinner.
Each tip type has its design differences in addition to the shape of the side surface. Therefore, regardless of the repair method, you must also pay attention to the following parts of the blade design:
From a technical point of view, all repair work can be divided into categories of complexity depending on the blade structure and maintainability:
Category 1. The first category includes the most common and most repairable blades. In other words, the repair of such blades will turn out to be quite an obvious and straightforward objective. For example, if we take from the table below the blade of knife types 1 and 6, the rising of the cutting edge in case of minor damage is quite obvious and you can implement it with simple technical steps. The situation is similar to that of repairing blades of types 4 and 6, except that here it concerns the knife spine.
Category 2. The second category of blades distinguishes knives that require the correction of two blade sides at once: both the spine and the cutting edge area. This includes blades of type 2 and 3.
Category 3. These cases involve the combination of the first two methods and any additional more complicated works. This might be necessary due to the complex structure of the bevels and the shape of the blade itself, which includes Type 7 and Type 8 blades.
The difficulty in repairing Type 7 and 8 blades is due to their symmetrical shape. It is a very difficult task to fix several edges and to maintain the correct geometry of each edge converging at the tip. If you add to all this the possible presence of concave (hollow or full hollow) bevels, the task becomes a lot more complicated. Not every knife maker has enough different grinder wheels on hand to solve such an issue.
If the knife has combined bevel types or a unique profile, there is a chance that very few masters will be willing to fix it.
|
Type of |
Raise |
Lower |
Combination |
Significant |
Category of |
|
1. Normal Blade |
• |
− |
− |
− |
1 |
|
2. Drop Point Blade |
• |
• |
• |
− |
1, 2 |
|
3. Clip Point Blade |
• |
• |
• |
− |
1, 2 |
|
4. Sheepfoot Blade |
− |
• |
− |
− |
1 |
|
5. Wharncliffe Blade |
− |
• |
− |
− |
1 |
|
6. Trailing Point |
• |
− |
− |
− |
1 |
|
7. Dagger Blade |
− |
− |
− |
• |
3 |
|
8. Spear Point Blade |
− |
− |
− |
• |
3 |
Table 1. Complexity categories and repair methods
The entire repair process can be divided into three main stages:
By now, you likely understand that all three methods can be applied to a fixed knife, but for folding knives, it is important to assess each situation individually. The restoration can be time-consuming and depends on the shape of the blade, the size of the broken part itself, and the hardness of the steel.
You need to keep in mind that as part of the repair, you will have to deal with both, the reprofiling work and also spend some time sharpening the reshaped knife blade.
All of this requires proper equipment and some experience in repairing such damages.
The fastest way to reprofile a blade or change its shape is using a grinding machine. However you will have to give the blade a proper sharpening afterwards. A fixed angle guided sharpening system is the best tool for high quality sharpening. Besides, if the broken part is just a small portion, you could even fix the damage with a guided system.
One of the best precision guided sharpening systems is TSPROF K03 Pro. This is the largest system from the line of TSPROF sharpeners. It is a rigid, multi-purpose full metal professional tool with well-thought engineering for top notch sharpening.
It has a rack and pinion angle setting unit for one hand angle adjustment with small increments, strong clamps and a semi-automatic knife flipping mechanism, which allows you to sharpen both knife sides without removing the knife from clamps.
This article is intended to offer guidance and specific ideas for users to be able to repair their knife blades on their own. It will also give you an insight into the possible requirements that you should discuss with a professional before handing over your blade for repair, ensuring you avoid any surprises.
Finally, in order not to break the tip, you should try not to use it to pry hard and viscous objects, use it as a screwdriver, or make heavy knife tests that show the limits of the blades' capabilities.
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