Hello, Homedepotcustomer - We're sorry to hear that the chuck key didn't fit your drill! Our 5/8 in. chuck key with 5/16 in. pilot is designed for use with most RYOBI drill presses and most large drill presses. And we'd like to check to see if your model is compatible so that we can provide you with support. If you would, please reach out to us at Reviews@RYOBItools.com.