There's not an absolute answer to this question. Sure, the chuck can be finger tightened, however, if you feel you are not strong enough to finger tighten the accessory and have it held successfully in the tool for the duration of your application, we recommend you consider using a wrench to tighten the chuck – there are flats on the sides of the chuck. The real answer to the question is that you try finger tightening the accessory – if it seems loose, use the wrench. If it still seem like it is not tight enough – see the next question.