I am seeking a design for a set of self centering guides that will allow a slip fit for tubing. The tubes measure from approx .022 up to .109. At the present time we are using a teflon insert placed into a brass housing. The process workes well but it is very labor intensive considering inserting the teflon ( press fit ) and boring the hole dimension. I have found some micro lathe chucks, but it seams as if they require a Lock down clamping pressure. I am thinking a spring loaded cam action with three cams. Any Ideas???