What is racking?
What is racking? |
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When using a woodworking vice, racking is a problem that may occur due to the design and structure of the tool.
Racking is when the pressure from the vice jaws onto a workpiece is not equal because the sliding jaw is not parallel to the stationary jaw. |
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It often occurs when an object is clamped at one end of a vice, with nothing to balance the load at the opposite end. This then means that the vice closes unequally, resulting in an angled jaw and uneven clamping pressure on the workpiece. | |||
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Consequently, if a workpiece is held unevenly, it is likely to slide or vibrate when a user tries to work on it.
There are two types of racking: top-to-bottom racking and side-to-side racking. |
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Top-to-bottom racking |
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Top-to-bottom racking occurs when a workpiece is clamped at the top of the jaws. When this happens, the top edge of the sliding jaw tends to tilt away from the clamped workpiece, leaving the object to be pinched at the bottom. This means there is uneven pressure applied to the workpiece, causing it to slip or vibrate within the jaws. | |||
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This happens when the screw and guide bars are at the bottom of the vice, because if they are loosely fitted then the sliding jaw will not get enough support and will tilt outwards.
Top-to-bottom racking is most likely to take place when using plain screw and quick-release woodwork vices, due to their structure. |
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A solution to this type of racking is a toe-in feature. This can either be already installed into a vice by the manufacturer… | |||
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…Or can be self-built by the user in the form of a tapered jaw pad.
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Side-to-side racking |
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Side-to-side racking occurs when a workpiece is clamped at one side of the vice jaws. As there is nothing to balance the clamping pressure on the other side of the jaws, the pressure is uneven, meaning the object is not held securely and can move or vibrate during applications. | |||
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This happens, similarly to top-to-bottom racking, due to a lack of jaw support from the guide bars.
Side-to-side racking can occur with all types of woodworking vices, but is most likely to happen with face workbench vices. This is due to the design of their jaws which are usually much wider than other types of vice. |
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There are two solutions to side-to-side racking. The first is a manufacturing solution, whereby the screw is offset, meaning it is set closer to the right guide bar than the left. This helps to avoid the risk of racking when clamping a workpiece on one side of the vice jaws. | |||
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The second solution can be created by the user themselves, by simply placing a wooden spacer block, the same thickness as the workpiece, in the opposite side of the jaws. | |||
