Knurled adjusting knobs are frequently seen on engineering tools and optical instruments. The raised pattern allows for more of a grip when turning a knob and the pattern is known as a "knurl". These knurls are generally formed using a knurling tool fitted to an engineers lathe. I own a commercially made knurling tool like this:

 

 

 but it will not form a knurl as good as this:

 

 

So I decided to make one that would. Here it is:

 

 

 

I made it from scrap metal, the "arms" were made from a stainless steel cupboard handle. The only things I never made on it are the small patterned knurling wheels and the three screws holding down the keep plate (although I did dress and polish the heads on the screws). This version of a knurling tool is based on a design which was originally manufactured by a company called MARLCO and is considered to be the Rolls Royce of knurling tools. I believe the improvements I have incorporated into my tool make it superior to the MARLCO so I hope I might be excused for comparing it to a Lamborghini!

Overall length is almost seven inches and it weighs one kilo - a hefty tool.

 Doing a bit at a time I worked at it for maybe two months as I am in no rush these days. It gives me pleasure to reflect that at a day rate of say £15 an hour for a toolmaker, someone would need to take out a bank loan to buy my tool :-)