Trade Secrets: Making and using a simple collar for self-centring


A useful tool for bow makers, enabling octagonal sections to be accurately centred in a three-jaw lathe chuck

Making or restoring a bow button with an octagonal cross-section requires the button to be centred accurately in the lathe. Most small engineering lathes are supplied with three-jaw self-centring chucks, designed to accommodate items with round or hexagonal cross-sections, but not octagonal. Four-jaw chucks are available as accessories for most lathes. These have independent jaws and are designed to hold items with rectangular or irregular cross-sections. Octagonal cross-sections can be accommodated in these but, since each lathe jaw is independent, centring becomes a very time-consuming task…

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