Interesting configuration for a drill bit. The center point locates, the one end of the bit cuts the diameter of the hole while the other chisel edge removes the material.
It's a really practical design, made by many different firms from the 18th to the 29th century. Because the rim is cut by the down-facing nicker, holes are generally very clean and smooth.
3 comments:
It's a really practical design, made by many different firms from the 18th to the 29th century. Because the rim is cut by the down-facing nicker, holes are generally very clean and smooth.
...until you hit a hard knot...
...but not this one... D.
https://www.bbc.co.uk/travel/article/20211213-the-hardknott-pass-britains-wildest-road
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