I used a wood owl 3/4 in bit at first, but those were too small for my bench dogs. For whatever reason a 13/16 bit was needed, so I bought this one and it worked great; perfect size: https://www.amazon.com/gp/product/B00004YO6U/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1