Cold shuts are one of the most common errors in blacksmithing and frequently occur during welding. If you are a blacksmith, you have probably heard the term but may not know what it is or how to prevent it.
In blacksmithing, a cold shut is a defect in welding that occurs when metal folds over itself during forging, either as the result of misaligned surfaces intersecting or as a result of welding at too low or high a temperature.
This article will provide thorough information about what a cold shut is, why it occurs, and how to prevent it so you can create clean pieces with minimal error.
Cold shuts in blacksmithing are also known as laps or folds. Basically, cold shuts manifest as cracks and lumps in your piece’s metal, as the metal folds over itself when it is improperly fused during forging.
They are problematic because they can cause your pieces to break and crack earlier than expected because they compromise the structural integrity, making it less stable and strong.
Moreover, they are not visually appealing and can be tedious to manage.
A cold shut will occur when a section of metal overlaps the parent bar when shaped, and then the overlap is worked back into the parent bar.
This phenomenon can occur in a few ways and is commonly seen when working with edges.
Generally, cold shuts are most likely when creating a piece with some kind of corner or sharp edges.
When Do Cold Shuts Happen?
Cold shuts are easily formed when working with corners because slight misalignment can cause you to strike your piece in the wrong spot and push sections of metal over each other.
Also, the piece can easily come away from the corner you are using to shape it, so small movements during forging have large repercussions.
One mistake that causes imperfections like this is a misplaced blow from your hammer that hits the edge of the workpiece, creating this issue.
The edge of the metal will be pushed down, making a physical deformation on the piece’s side, and leaving the surface uneven where the excess metal was pushed. When you attempt to correct it by hammering the metal lump back into the piece, a cold shut is created.
Hammering a square corner also creates a cold shut because the metal is pushed into the corner of the piece, and it drags other metal with it.
As you hammer to correct it, the problem worsens. This could also occur from misplaced hammer blows.
When you hammer a metal piece on a corner to attempt to replicate the corner on the piece, a cold shut can be created.
This occurs when the edge of your piece becomes misaligned with the corner you are hammering on, causing the wrong part of the metal to be hammered.
During this process, the corner you are creating will become dented or flat, beginning a cold shut.
Clearly, there is a multitude of ways to create a cold shut, making them almost inevitable during the welding process.
How Can You Prevent a Cold Shut?
Fortunately, there are a few ways to prevent this problem happen. Primarily, cold shut prevention involves working mindfully and carefully, using rounder anvils, and working at the correct forging temperature.
Cold shuts may seem inevitable, but these tips may help you minimize their number and impact.
To prevent it in square corners, you can try hammering on the horn of the anvil.
Hammering on the horn of the anvil when making square corners will help you combat the error by increasing the time it takes to form a cold shut and using corners that are less sharp and extreme, so it is less likely to become a cold shut.
While cold shuts can still form, they will be slower, so you can address the problem before it is exacerbated.
Moreover, if you have an anvil with very sharp corners, you are more likely to have a cold shut because it struggles to slowly inch the metal into a corner- rather, it tends to rapidly create a corner with a large margin of error and may create corners that are too sharp and dented.
Therefore, using a rounder anvil or a round section of the anvil (such as the horn) can help you ensure you do not create cold shuts as rapidly or easily when shaping corners.
Hitting your piece when it is not in the proper position is a common cause of cold shuts, so paying close attention to your work is vital.
During forging, try to maintain awareness of your metal’s position- you should be able to tell if your piece is properly in line with the anvil’s corner, so try to keep the corners aligned correctly, so it does not slip.
Then, if you feel the piece coming away from the corner, realign it before continuing to hammer- do not let it simply shift around the anvil without keeping control over the piece.
Overall, looking and feeling to confirm your piece is in the correct position will help prevent these imperfections.
Another way to prevent a cold shut is to confirm you are working at the correct forging temperature.
When you heat your metal to red and black heat, you are more likely to create a forging imperfection because the core of your metal will not move as much as the hot and malleable top of the metal.
However, be careful because if your metal is too cool, it will harden faster and make it more challenging for you to correct the cold shut promptly.
How Do You Fix a Cold Shut?
While preventing cold shuts should be your primary goal, they will still occasionally occur. Luckily, they can be manually fixed, ideally while the metal is still hot.
If you catch an imperfection in your piece, you should try to fix it as quickly as possible.
One way to do this is to heat your piece back to a firm yellow heat, then physically correct the error as best as you can using a file or hot brass. This can simply be done by clamping the piece and working only on the section with problems.
You can also use an angle grinder to grind the cold shuts out of your workpiece until they are gone.
This method works well for cold shuts that occur in corners because you can easily use your angle grinder to create a sharper angle as you work.
To remove a cold shut using an angle grinder, simply wait for the metal to cool, then use the angle grinder to chisel the dent out of your workpiece.
In conclusion, cold shuts are a tricky aspect of blacksmithing that occurs when metal overlaps itself after being hit by a hammer and forces over itself.
To prevent a cold shut, you can avoid working on sharp corners and use the part of an anvil with rounded corners, enabling you to gradually create smooth edges without flaws.
Because they might weaken the workpiece’s structure, it is important to work to prevent them when welding.
However, when you create a cold shut, you can fix it rapidly using a file or angle grinder, allowing you to avoid the consequences of this common mistake.
Cheers, tools owners!