This torque wrench should be used when changing nozzle on "The Olsson Block": http://umforum.ultimaker.com/index.php?/topic/7689-custom-heater-block-to-fit-e3d-nozzle-on-ultimake...When you have reached the right tightening torque, the tool will start slipping (making clicking sounds). This prevents damages from over-tightening or leaks caused by too loosely tightened nozzle. When unscrewing the nozzle however, torque is unlimited.The tool also prevents you from accidentally tighten the nozzle in case you forgot which way to turn to unscrew it.Use 100% infill and make sure you don't have under extrusion, or the tool will be too weak.For PLA, I recommend to leave fans on auto and print both pieces at the same time using the "print all at once" option in Cura. This will give the plastic sufficient time to cool. Printing the pieces "one at the time" with PLA normally also works, but will give less smooth overhangs.For ABS i recommend printing "one at a time" with fans at auto. If you print them "all at the same time" with ABS, leave the fans off as too much cooling might give insufficient layer bonding and the tool might then break.When printed in PLA with the square socket-holder you have to be reasonably quick when changing a hot nozzle, or the tool will start melting. If you end up with strength/temperature-issues, you can consider to print the internal hex hole version instead. (thank you UltiArjan for coming up with the hex hole idea)The torque wrench has been test-printed in PLA, ABS and XT.The torque will vary a bit, from about 0.25 Nm to about 0.5 Nm, depending on the type of plastic. (ABS and XT is softer, PLA harder).You can of course try this tool on other printer nozzles or for other purposes, but I can not predict the outcome of such uses, do it on your own risk!Note for resellers: This design is shared under the Non-Commercial Share Alike license. However, if you are an official dealer of "The Olsson Block" and your customer does not want to print the torque wrench, I don't mind if you charge a reasonable amount for printing the tool for the customer.