I need to find a quill bit in 5/16" size. Friday, while I was inventorying the contents of the cooper's shop at Sutter's Fort, I discovered a broken 19th Century barrel head. Found all the parts, and was able to measure the dowels used to join the several boards that make the head. All the dowels were 5/16" diameter, so we'll need to find a proper early to mid-1800s bit.