I am building a large delta printer and designed the carriages around a V-rail and printed carriage with 3 (or 4) of these wheel kits. After thinking I had designed a weak carriage I finally realized the delrin wheels would wobble on a tightened assembly, every one! I understand that by design the precision 1 mm thick shim that goes inside is supposed to match the inside ridge of the wheel, but apparently that ridge is a hair short. This either isn't right, or I am trying for more precision than these are intended for. I can feel the play with my hands. It is not a lot but in the right design that slight amount translates to a lot of tilt. The wheel is not actually clamped onto anywhere, it is a 'precision' fit. Has anybody else encountered this? The only solution I can think of is to reduce the thickness of the shim until the play is gone, except I dont' have any tools to shave it down squarely. That would also throw off the wheel height from the mounting surface, although maybe not enough to matter for my application.