Heavy-Duty AquaPure water filter wrench by rodsmith

Last crawled date: 3 years, 4 months ago

Introduction
This Thing is designed to replace the cheap housing wrench that comes with the 3M AP (AquaPure) 800-series water filters. The supplied wrench breaks easily and has a handle that's too short to provide enough torque, so this one is larger and uses a wooden handle (like from a shovel) or similar, which can be as long as desired/necessary to provide the necessary torque.
I've had recurring problems unscrewing my water filter housing, and have had the best luck using a large metal plumber's wrench, but it wasn't designed for this task and so it frequently slipped loose. It was also gouging into the plastic tracks that are meant to provide a grip for the wrench. Thus, I created this Thing. Rather than provide a complete handle, I designed this Thing with a hole into which a longer handle can be inserted, thus providing more moment arm.
I've tested this design with the AP801 in my house. It was, by far, the easiest time I've had changing my filter, although it still took some muscle to do the job.
Preparing to Print
I provide two .stl files for this Thing: water-filter-wrench.stl and water-filter-wrench-fit-test.stl. The first of these is the full wrench, and the second is a truncated version intended to be printed with minimal infill so as to test the fit of whatever handle you choose.
To that end, you may need to modify this Thing by editing the provided .scad file and recompiling the .stl files using OpenSCAD or the Thingiverse Customizer. You're most likely to want to adjust three variables:
The buildItAll variable sets whether to build the entire wrench (with a value of 1) or just the fit-test piece (0). If you make significant changes to other variables, you're likely to want to build both pieces.
The handleDiam variable sets the diameter of the hole into which you insert your handle. The default is 28.5 (mm), which is designed around the old shovel handle I used. If you use something of a different size, you'll need to adjust this value.
You may also need to adjust height, particularly if you use a handle with a significantly larger diameter than mine. If you use a handle with a smaller diameter, you can probably get away with decreasing height, which will also decrease the print time.
If you want to use this design with water filters other than the 3M AP 800-series, you may need to adjust other variables, too.
Printing and Use
You can print with low-resolution layers (I used 0.3mm) to speed up the print.
Before printing water-filter-wrench.stl, you'll probably want to print water-filter-wrench-fit-test.stl. Print the latter with minimal infill; but print the former with at least three or four perimeters and plenty of infill, since it will need to survive considerable force. I used four perimeters and 50% infill.
Printing this Thing was a challenge because of its size. I tried both PETG and PLA. I had problems printing such a large object in PETG, because I've been adjusting my printer and haven't yet gotten it properly tuned. My best PETG attempt failed because of a layer shift at about 90%, which was probably good enough. Another attempt finished, but the handle-mount area lifted up during the print, thus deforming the handle hole. It could probably be fixed with the help of a rotary cutter. My best print was in PLA, and that's what I used (and have shown in photos). I wasn't happy with the way the blue PLA with which I started was going down, so I switched over to black for everything past the first two layers.
When I used my wrench, I found that even the ~28mm-diameter wooden handle bent significantly, and I feared it might break, but it didn't. Using a solid metal cylinder might work better.
Depending on the installation details, putting too much force on the filter housing could conceivably damage your plumbing, so be careful!
THIS WRENCH SHOULD BE USED TO REMOVE THE FILTER HOUSING. DO NOT USE IT TO TIGHTEN THE FILTER HOUSING!