Hi

I also made a collet arrangement to hold small thin pieces for facing off etc but I have made a draw bolt attachment that pulls up onto a taper insert that then fits into my 3 jaw chuck.
I have always fitted it to line up with the # 1 jaw so as to maintain concentricity, I have made two, one for large diameters & t'other for smaller. The actual internal diameters I made to standard diameters e.g. 12mm,16mm, 25mm,but these can be machined to suit whatever size you require.
Hope the photos show up ok.




Cheers
George