PSU lock for Prusa Enclosure V2
I'm in the middle of printing parts for the Prusa Enclosure V2 (which although I'm using a stock MK3S is designed for the MMU2 unit so I suppose this post belongs here more than anywhere else). I wanted to mount my black model PSU externally so I could print ABS without having to worry about electronics overheating. In the instructions the silver model PSU has a reliable solution for mounting, but I wasn't too keen on the "single screw into fibreboard" solution for securing the black model PSU against the mounting bracket because it requires removal of the PSU cover in an awkward position to access it, and makes repeated removal and replacement difficult without wearing out the screw hole in the table.
I've designed a spring-loaded lock to replace this single screw. The spring holds the lock's bolt inside the PSU, in the gap through the PSU cover above the electrical wires, and prevents the PSU from moving. Pulling back the bolt will disengage the lock from the PSU and allows the PSU to drop out far enough to be pulled out of the bracket on the other side.
https://www.prusaprinters.org/prints/5777-black-psu-lock-for-prusa-printer-enclosure-v2
RE: PSU lock for Prusa Enclosure V2
What type of spring is that?
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Chuck H
3D Printer Review Blog
RE: PSU lock for Prusa Enclosure V2
To be completely honest it's from a big box labelled "springs" that I inherited (full of a wide range of anything from shock absorbers to watch springs) selected for having an appropriate force and length for the application. It's about 45mm long, 8mm diameter and made from approximately 0.5mm diameter spring steel wire.
I wasn't sure how ubiquitous such a spring might be so I've made the lock capable of coping with any spring between 5mm and 10mm diameter. As long as the spring is within that diameter range, pushes back slightly when compressed down to length 32mm (the furthest extension of the lock rounded up), and can be fully compressed without excessive manual force down to 14mm (the furthest retraction of the lock rounded down), then it should be fine.
If anyone knows of an easily-sourced spring suitable for the task that does not fit the above limits, I still have the source 3D cad file and can modify it to fit any spring larger than these dimensions and then quote it in the print instructions. It can't realistically be smaller than the minimum diameter of 5mm because that would make the printed securing peg too fragile, and although the lock could be modified to accept a spring of length as short as its length when fully compressed plus 16.8mm (the full range of movement of the bolt) the peg risks being too short to hold the spring on without allowing it to buckle into the space behind the bolt.