The performance of a pencil sharpener depends on the characteristics of its blade. If it is made of poor steel or is not properly hardened, then its edge will wear out quickly. Here is a proof of the lousy work:
The cut turned out to be slightly crooked, the rod was slightly broken off.
The situation can be corrected by heat treating the blade and then sharpening it. This is tedious work, perhaps not even practical for a regular sharpener, but it will provide excellent experience that can be useful in making or improving knives.
Materials and tools:
- crosshead screwdriver;
- pliers;
- sunflower oil;
- sharpening stones;
- polishing paste;
- sharpening angle holder.
Heat treatment and sharpening of the sharpener blade
The secret of an ideal cutting tool, in addition to good steel, lies in its proper heat treatment. The blade must be normalized, hardened and tempered. Normalization will make the metal structure homogeneous and relieve internal stress. Tempering will impart hardness, which is necessary to maintain the sharpness. Tempering will return the hard blade's ductility to prevent it from breaking.
You need to remove the blade from the sharpener and place it on a screwdriver over the fire.
Since it is very thin, the combustion of the gas is enough to heat the steel to a crimson color. After this, the blade is removed from the heat and left to cool in the air. This will normalize the metal. If the blade has manufacturing defects, it can be forged a little while it is hot.
The cooled blade warms up again, but not to a crimson hue, but to a light orange color.
As soon as it warms up enough, it is thrown into water at room temperature for hardening.
Next, the hardened blade must be subjected to low tempering. To do this, throw it into vegetable oil heated in a frying pan at 200 degrees Celsius for 1 hour.
It is important to maintain exactly this temperature throughout the entire hour. If you don’t have a thermometer to control it, you can simply throw the blade into a container of oil in an oven with a thermostat.
The blade is ground with water on a grindstone with 2000 grit.
Next, it is clamped in the angle holder and sharpened on the same stone along the edge.
Gradually you need to switch to an abrasive with a finer grain. The example uses stones “6000”, “8000”, “12000” and “30000”.
Finally, the blade can be treated with polishing paste to make it look like a mirror.
A blade that has been properly heat treated and sharpened to a mirror shine will be able to grind pencils perfectly. Cuts paper perfectly.
Place the blade in the sharpener.
The hard metal cutting edge will cut for a very long time without the need for re-dressing.
Pencils now sharpen just perfectly.
This sharpener will now last for many, many years.
