Jumbo drills are large, heavy-duty machines commonly used in mining and tunneling to drill multiple holes simultaneously. But the diameter of the holes drilled by a jumbo drill can vary significantly depending on the specific model and its intended application.

　　The exact diameter depends on the specific model and the type of drill bits used, but typically, jumbo drills can create holes with diameters ranging from 30 mm to 102 mm (1.18 to 4 inches). Some specialized machines may handle larger or smaller diameters depending on the requirements of the operation.

　　However, there are specialized models designed for even larger holes, which can sometimes exceed several feet in diameter for particular purposes such as raising boring or ventilation shaft creation.

　　It's important to note that while "jumbo" refers to their ability to handle larger hole sizes compared to regular drilling equipment, the exact specifications can differ widely among manufacturers and specific drill designs. For instance, Atlas Copco Boomer series jumbo drills were historically known for handling hole diameters up to around 6 inches, whereas larger specialized drills might go much bigger, potentially reaching up to 2 meters (about 6.5 feet) in diameter under custom configurations.

　　Thus, the term "jumbo drill" encompasses a variety of drilling machines that share the common characteristic of being able to create substantially larger holes than those made possible by traditional handheld or small-scale drilling units. The actual diameter depends on factors such as the type of rock being drilled, the purpose of the hole, and the specific technical limitations and capabilities of the drill itself.