Twisting not only generates an easily recognisable pattern with just a straight laminate, it’s also one of the most important operations in making a lot of other patterns.
Making a simple “twist pattern” is relatively straightforward, but there are a few important things to know to get the most out of your twists. The basic steps of a regular twist pattern are:
- Create a straight laminate billet
- Draw it down, as evenly as possible, to a square cross section (The size here determines a few things that are discussed below).
- Forge the sharp corners back into the billet, making it slightly octagon shaped.
- Heat the billet as evenly as possbile
- Clamp one end of the heated billet in a vise and begin to twist the other end with a twisting wrench
- Once you’re happy with the twist of your billet, reheat it
- Wire brush and flux the twisted billet
- Forge the billet back to square at a welding heat. This will cause the “corners” to weld back into the billet as you work it. Make sure to brush well and flux after each of these heats.
- Draw your billet into a bar
- Grind your billet clean, making sure to remove any surface defects or cold shuts left from the “corners” in twisting.
Sounds simple right ? It is, but there are a few potential trouble spots. See the patterning operations section for more information on twisting.
There are a few variations on the twist pattern that greatly affect how the pattern looks.
How many layers are in your billet prior to twisting has a dramatic effect on what your pattern will look like. A low layer count twist will be very bold and striking, as in the this picture.
A higher layer count will yeild a much more fine pattern sometimes referred to as a “Maiden’s Hair” pattern.
Again, there are no hard and fast rules to how you build your billets. Alternate bands of higher layered steel with single pieces for a bold twist that has some fine details when closely inspected. Stack your steel in different chicknesses and see what happens, come up with anything you like and just go for it. Twisting will take things that may seem not at all exciting and make them amazing.
Rate of Twist.
What I call “Rate of Twist” is basically how tightly you twist your billet. Most people, even very experienced ‘smiths, would be suprised at how many twists a given piece of steel can handle without any ill effects. For the sake of simplicity, I’ll refer to rate of twist in “twists per inch” as it makes for a very consistant method of explaining how much twist a given pattern needs. For example, if you have a billet that is 8″ long and you assume you will have 1″ at each end that you won’t be twisting (for the vise and wrench to grab) and a pattern calls for “1 twist per inch” you would twist that remaining 6″ section 6 full rotations.
A loosely twisted billet of less than 1 twist per inch will have a rather “open” appearance to the pattern (as pictured above). At 2-3 twists per inch you’re creating a twist suitable for a “Star Pattern” billet. 5 twists per inch is about right for a multi-bar “Turkish Twist” pattern. Greater than 5 twists per inch is very tight and you’ll start to see some interesting differences in your pattern.
Size of Bar Prior to Twisting
Because of the fact that a square billet is rarely desired, most twists will be drawn down into a bar. The size of the twisted bar compared to the size of the finished bar can have a dramatic effect on your pattern. This is due to the fact that as you flatten a square bar, you will be drawing it lengthwise as you go. As you draw the bar in length you “stretch” the twist out. the larger the twisted bar, the more drawing you must do and hence, the more stretching of your twist will be seen. For this reason I generally increase the rate of twist slightly over what I THINK I need. That way, when the bar is drawn down the observed rate of twist will be what I expected.