Designed to fit my 2021 model "Drop Lampi" hot tub. Probably also works with some other Drop models and maybe others by same manufacturer ("Novitek"). In these older models the water filter is located inside the side panel (not the step). I assume there are more brands which use same setup and identical water filter box.
The problem that necessitated this design is following: This water filter box has a locking ring which has very bad design and almost no grip. The ring needs quite a bit of force to open and close all the way to the position where its locking tab engages. After struggling with it a few years I've finally lost hope of it loosening up over time, so I decided to make a proper beefy handle that engages with the awful locking ring, and lets me change the filter without any struggle using a nice hefty easy to grip handle.
Designed to snugly fit on the locking ring, and stay in place permanently. Since there is no holding tabs or anything on this, it's not actually permanently fixed though.
There is no way this fits my Prusa MK4S bed, so in Prusa Slicer I split this into 4 parts, and added locking pins to the cut surfaces.
If you cut this by yourself in slicer, add snap-on pins that are about 10-15mm in size. At least one surface doesn't have room for a 15mm pin - I used 10mm there, and 15mm elsewhere. All pins were 15mm deep. Then paint on supports to the protruding pins. Use 0.2mm tolerance for the locking pins. It will be very tight but eventually snap in. That's good - you don't want this to have any wobble.
To assemble, first connect parts 1 and 2 together, to make a semi-circle. Next, connect parts 3 and 4 together to make another semi-circle. Then connect the two together. If you do not follow this order, then you run into problem connecting the last piece. You need to push the locking pins straight on, that's why it's necessary to make first two semi-circles, and only then connect those together.
There are two ways to assemble this:
I suggest you use method 1, and wrap the outer ring with steering wheel leather. This will fortify the outer ring so tight that the inner ring has no wiggle at all. Alternative ways to reinforce the outer rim probably exist, but this is what I had laying around, so I didn't even look into other ways to accomplish this.
Optional method 2 using 4, 8, or 12 zip ties. To do this, you need to customize the OpenSCAD file, and re-generate the STL, cut to parts in slicer and add the locking pins by yourself. OpenSCAD file has variables to enable/disable the zip tie holes in both inner ring (8 zip ties) and outer ring (4 zip ties). I have tested this with 12 zip ties. You can probably customize it to have different numbers of holes too, but that's just the configuration I used before making new revision that doesn't take zip ties but uses steering wheel leather wrap instead. The wrapped result is cleaner, so I encourage you to reconsider method 1.
To install into the water filter box locking ring, push it in straight from forward. It is going to feel like it doesn't fit, but if you force it a bit, it will eventually go in (and make some cracking noise, as the locking pins are giving way a little). This tight friction fit will make sure that it does not fall off and engages properly with the locking ring.
The OpenSCAD source code is almost fully parametric, since I’m very lazy programmer, and forget which numbers are what unless I use good variable names.
However, please note that my goal for this project always was to find a solution to my particular problem, and as soon as I got the solution, I stopped working on the code. I only added comments to help you understand what’s going on in the code. It was not tested with other configurations, such as different size handles or different numbers of spokes. The parameters are there for easy customization, but other values are completely untested.
Please also note that the model is pretty big and uses minkowski(), so you better use the latest OpenSCAD with fast rendering.
Have fun with the OpenSCAD file, and let me know if you made a better one!
1.2 - Dec 2024
1.1 - Nov 2024
The author marked this model as their own original creation.
