Choosing Quality Lathe Chisels
With so many tool choices for turners on the market today, it can be tough to decide what is worth purchasing, and what is not. While the types of tools that each person will enjoy using will vary, we would like to clarify the differences between the types of steel that are used in tools. Understanding the differences between the materials that tools are made from will help you select tools that are appropriate for your needs, and save you the headaches of buying tools that will not perform as they should. Let's look at the different types of tool steel available on the market today:
Carbon Steel -
Carbon steel tools were the industry standard for many years, but have been replaced almost entirely today by longer lasting high speed steel. Carbon steel tools are still available today, but usually only as lower quality, inexpensively produced sets. The smaller price tag associated with these tools can make them an attractive option for new turners, but are not a good choice. Carbon steel tools will lose their temper (i.e. will no longer hold a sharp edge) if they are sharpened too aggressively, causing the edge to turn blue. Carbon steel tools will, however, hold a sharper edge than other types of steel, but only for a short period of time. This said, carbon steel is recommended only for occasions in which an extremely sharp edge needs to be used to clean up a piece during the final few cuts.
High Speed Steel -
There are a wide variety of high speed steels available in the market today. The most commonly found types are M2 and M4 HSS (high speed steel). There are also cryogenically treated types of high speed steel, which we will discuss further in one of the following sections. High speed steels offer at least two main benefits. Quality high speed steels will maintain a sharpened edge longer than carbon steel, and they also will not lose their temper (ability to hold a sharpened edge) if ground too aggressively and caused to blue. High speed steel tools are more expensive than carbon steel tools, but are an excellent choice for turners of all skill levels. Spending a little bit of extra money on high speed steel tools will greatly increase the time you spend turning, rather than the amount of time you spend sharpening. One extra note, though - beware of inexpensive tools that are stamped as being made of high speed steel. Although the tools may be high speed steel, they are likely made of a very low grade variety and may not perform as well as others.
Carbide tools are the ultimate choice for those persons who don't wish to sharpen their tools regularly. As carbide is significantly more expensive to produce than carbon or high speed steel, you will see these tools sold with interchangeable cutters mounted on the end of the tool. These tips can be rotated to expose an unused portion of the cutter, or can be replaced when totally worn. Carbide will stay sharp for a much longer period of time than other tools, but will also not hold as sharp of an edge as other types of steel. If using carbide tools, you'll get the best results by using a fresh, unused portion of the tool to make your final few cuts. Switch back to a more heavily worn section of the tool for the majority of the turning process.
Cryogenically Treated Tools -
Typically, high speed steel is the most readily available type of cryogenically treated steel. The cryogenic treatment process improves wear resistance in tools, often allowing for 2X - 3X the usage (when compared to similar steel which is untreated) before the tool must be resharpened. Cryogenically treated steel will come at a slight premium in comparison to their untreated counterparts. Highly recommended for persons who do large volumes of turning, as cutting ability is nearly identical to the untreated tools, while sharpness is retained for a longer period of time.