The size of a guide bush can vary depending on the manufacturer and the specific application. However, guide bushes are typically available in a range of standard sizes. The most common size is 1/4 inch, which is compatible with many common router bits. Other common sizes include 3/8 inch, 1/2 inch, and 8mm. Some guide bushes are also available in metric sizes, such as 6mm, 12mm, and 16mm.
It is important to choose the right size guide bush for the specific cutting tool being used. If the guide bush is too small, it will not provide adequate support and guidance for the tool, which can lead to inaccurate cuts and increased vibration. If the guide bush is too large, the tool may not fit securely, which can also lead to poor-quality cuts.
The most common guide bush size is 1/4 inch, this size is used on many routers and is compatible with a wide range of router bits. However, some guide bushes are also available in other sizes, such as 3/8 inch, 1 /2inch, and 8mm.
It's important to check the compatibility of the guide bush with the router and the bit that you're using. Some guide bushes are designed to be used with a specific model of router or a certain type of cutting tool. So make sure to check the compatibility before purchasing.