Metal Spring Adapter for Universal Auto-Rewind Spoolholder

Update (26. April, 2024): I have pushed the design to Version 2. This now requires a 6900-2RS Bearing (10mm*22mm*6mm) behind the metal coil adapter. Diameter of the metal spring housing needed to be smaller than in the first version. With the large diameter as it was, the angle of the metal spring towards the axle did not create a rotational force anymore. Another type of bearing (10mm inner diameter, 6900-2RS) is now required for the part to work. This allows to integrate the spring axle into the bearing and makes the system operate smoother. The Axle now contains a sacrificial layer which can easly be cut out or just pushed through. This layer is on the bottom and improves bed adhesion. As far as my tests went with v2, this design now operates smoothly and reliable. I will update the model with some new photos soon. Original text: I really love the Universal auto-rewind spool holder design by Vincent Groenhuis. While I really like the printed spiral springs, I found them to be a weak-spot of the design in the long-term as they can break or simply change their properties with changing temperature and humidity. This remix targets this problem using a metal spring taken from those cheap auto-retract measurement tapes. You can get those tapes for very little money on amazon. I paid 10€ for 8 pieces. I originally didn't like the idea of buying the tapes and scrapping everything except the spring, but I simply found no other way of getting my hands on such springs. The tapes can retract about 150cm, so the spring should provide enough rewinding revolutions for most MMU setups. However, it does not provide as much torque as the original 3D-printed spring. If you need more torque, It might be necessary to take springs from one of those steel measurement tapes from the hardware store The adapter consists of only two parts, which completely replace the coil module of the original model. The assembly is pretty simple: print the two parts. printing parameters are irrelevant. Just take a 0.4 nozzle or smaller) crack open the housing of the measurement tape carefully unwind the measurement tape carefully take out the spring (Attention! The spring tends to suddenly unwind itself) bend the inner part of the spring to match the gaps on the axle part and push them inside push the bend on the outer end of the spring inside the slot on the housing you're done. Continue to assembly the universal auto-rewind spoolholder as shown in Vincents' video I used those tapes and bearings: https://www.amazon.de/dp/B074BTL9KV/ (Generic 150cm tape measure) https://www.amazon.de/dp/B08HH341JW/ (6900-2RS bearing, 10x22x6mm)