So this is NOT a post about the official ChaoticLabs Z-axis Tensioner, but a review of the AliExpress "Funssor" version. When I received the parts, I thought they looked OK and were well made. However when I went to swap the printed Z-axis tensioners, I ran into the first problem. The shoulder screws which were included did not fit the stock GT2 20 tooth (9mm) idlers. I measured them and found they were about 4.97mm in diameter so they should have fit, however when I checked the point where the threads stop and the shoulder begins, I noticed a very slight bump in the profile of the screw (under a microscope).
It's gonna be a while before I get the washers, so will update when these are finally installed.
Update 5/4/2023: I received the washers and installed the tensioners and have mixed feelings about them.
- Aluminum construction should be stronger than printed
- The knob is much easier to use than tensioning using an allen wrench
- The construction is not great, the shoulder bolts required filing, and the knob feels crunchy.
- Required ordering washers, which only helped somewhat.
- I'm not a fan of the way the pulley is held in. The shoulder bolt which holds the pulley cannot be fully tightened without seizing the pulley. The retaining bolt is also somewhat cantilevered, since one side is only supported by the bolt head. They could have just used the same design to retain the pulley as stock, and it would have been better.
Overall I would not recommend these. They look nice, but for the cost, they should operate smoothly and installation should not be such a pain. Since I was unable to fully tighten the bolts for the pulleys, I have little doubt that I will need to re-tighten them regularly or design some other solution. Again however, it should be noted that these were AliExpress knock offs, and are not Chaoticlabs branded tensioners, so I do not know if the genuine article would improve on the problems I experienced.