Another tweak to a MoonCactus design. This design prints the screw, locknut and base. I use this in conjunction with MoonCactus' Fully parametric bearing-friendly axis caps (non-adjustable). So I used one of MoonCactus' non-adjustable caps on one end and then my adjustable end cap on the other, but I suppose you could use an adjustable end cap on each end of the rod. MoonCactus suggested a shorter threaded component so it doesn't stick out so far, so I've included a shorter version that uses a 6mm hex key to adjust. 6/6/13 Update: I added two more low-profile components. AdjThreadSlot.stl and LockNutShort.stl. The AdjThreadSlot.stl is the shortest of all the screws and the short locknut is 2mm shorter than the original. You should be able to adjust the slotted screw with either a straight-blade or Phillips screwdriver. I should also note that if you like adding grease to the end of the shafts, it is very easy to remove the screw and place some grease on the end of the screw/shaft. Although not necessary for this design, I also included my variation of the inner bearing cap (Thing: 99113) with a hexagonal protrusion that hold the nuts in place.Base (EndCapThreaded.stl): 0.1mm slice, 0.8mm wall, 30% fill Screw (AdjThread.stl): 0.1mm slice, 0.4mm wall, 100% fill (less fill okay) Locknut (Locknut.stl): 0.1mm slice, 0.4mm wall, 100% fill (less fill okay) Inner Cap (InsideCap.stl): 0.2mm slice, 0.8mm wall, 30% fill press-fit the nuts into the hexagon protrusion before installing. Remove any "Z scars" on the screw with a knife or fingernail and thread the screw/nut/base in and out enough such that they adjust easily by hand. If they do not thread easily, it will be difficult to accurately set the clearance between the screw and the shaft with the potential to put the axis in a bind. Adjust the screw until it contacts the shaft, and then back it off some (about a 1/4 turn). You don't want to add any additional friction to the system, but merely reduce the axial movement of the shafts. You can also check the clearance by moving the rod back-and-forth until you are satisfied. Use the locknut to keep the screw in the adjusted position, but make certain the screw does not turn while tightening the locknut.