Should You Try To Temper Your Own Tools At Home?

Whether you're a professional carpenter or just a hobbyist, you may struggle with a constant dilemma when it comes to tool purchases. Purchasing inexpensive tools may leave you searching for a replacement part (or tool) after just a few projects, but buying tools made from tempered iron or steel can leave you without much room in your budget for other materials. Fortunately, some enterprising woodworkers and construction professionals have designed a cheap and effective workaround -- tempering your current tools from the comfort of your own home, using only a high-temperature oven and deep fryer. Read on to learn more about tempering your own tools, as well as what you should look for when determining whether a specific tool is a good candidate for this process.

Why temper your tools?

Although "hardness" may seem like a desirable quality in any metal tool, steel or iron that is too hard may be brittle and prone to breaking. Because of this, inexpensive non-tempered steel tools may actually be harder than tempered tools, but also less likely to hold up over a long period of use. As a result, many carpenters and contractors either opt to purchase steel tools that have already been tempered or temper their own tools after purchase. 

The tempering process involves using a blowtorch or other source of high heat to bring the steel to an ultra-high temperature deemed the "critical point," then immersing the steel into a bath of water or oil until it cools down to around 150 degrees Fahrenheit. The critical point can often be easily identified as the point at which magnets no longer stick to a piece of heated steel. 

After your steel has taken a cooling bath and achieved the desired temperature, you'll then rinse the steel off and heat it to a much lower temperature in an oven for approximately 20 minutes. The temperature to which you'll need to heat your oven depends on your tool -- screwdrivers and wrenches are best tempered at around 590 degrees Fahrenheit, while saws designed to cut metal should be tempered at around 400 degrees. Tempering your specific tool at a too-high temperature could cause it to become brittle, defeating the purpose of tempering in the first place.

What should you consider when deciding to temper your tools?

Before deciding whether to temper a specific tool, you'll want to take a few factors into account. The tempering process can be time-consuming and involves high heat, so you don't want to invest this time, money, and effort in a tool that isn't likely to survive the process. 

Your first step should be to determine the type of steel with which you're dealing. Because steel is an alloy rather than a pure metal, it often includes a variety of other metals, from iron to aluminum. Depending upon the type and quantity of outside metals present in a piece of steel, the steel may be classified as "oil-hardening" or "water-hardening" -- and placing an oil-hardening steel in water can quickly warp the metal, ruining it. If you have a tool you know is oil-hardening, you may want to use a grinder to shave off a small piece of both this tool and your unknown steel to see whether the sparks given off are the same color, indicating similar composition. 

Absent this "spark" test, the safest option is to use oil to harden the steel. Even if a particular piece is water-hardening rather than oil-hardening, the oil won't ruin the steel, and you'll then be able to try again with water after re-heating the steel to its critical point.

Finally, you'll want to evaluate the amount of time it will take to heat your steel to the critical point by testing with a thermometer on a small part of your tool. If this is your first time attempting to temper your own tool, you may want to begin with a relatively light and flat tool, like a knife blade or hatchet. Tempering thick wrenches and pliers may be too complex for the novice blacksmith, but most knives and other flat blades can be tempered by anyone with a blowtorch, oven, and countertop deep fryer. 

For more information about strengthening metals through heat, contact a company like Pacific Metallurgical Inc