I'm looking to cut a 125mm hole in 18mm OSB board, but it's really tight because it's just 10 cm away from a slanting roof. My current drill, the DCD805, is too bulky even with a right-angle attachment. I thought about trying the DCD740, but I've seen mixed reviews about its power and performance. Are there any 125mm hole saws that come with a 1/4 hex so I can use them with my DCF850 and the DT20500? Any other suggestions for tools or methods would be appreciated!
3 Answers
I've had some luck using the DCD740 for smaller 3" forstner bits, especially when working under a roof. It does heat up, but it gets the job done if you need to run wires down the wall.
Have you considered approaching it from the opposite side of the OSB? Also, Bosch offers a fantastic 1/4” keyless hole saw system that’s impact-rated, but it can be pricey. They sell some hex adaptors too, but the details can be a bit vague. Might be worth checking out!
It sounds like your challenge might be more about the depth of your hole saw and drill than anything else. A picture would really help clarify! For such a large hole, you might want to use an oscillating tool with a narrow blade to make plunge cuts around the circle. It could be a real lifesaver in tight spots like yours.

I found a budget option on Amazon that looks like it could work for the 1/4" hex setup. Check it out here: https://a.co/d/bz4Hwc8