CurrentRanger Modified Case for Heat-Set Inserts and Flat Lithium Battery

Background:

I have a CurrentRanger from lowpowerlab, which came with a case. Unfortunately I both lost the screws that hold the lid to the case, and the screws screw into somewhat flimsy looking plastic holes directly, which I was not a fan of. I have heat-set inserts and they are IMO one of the most “ideal” ways to have screws into 3D printed parts.

I downloaded the case file and used FreeCAD to crudely hack in some square “pillars” that would have enough width at the top to hold an M2 heat-set insert (3.2 mm ID hole). The original case screw mounts were not wide enough for this, you need a minimum wall thickness to hold heat-set inserts.

I then had a 1200 mAh, 3.7 V lithium battery from Adafruit I was intending to use as the power source for the CurrentRanger. However, being a soft-shell battery, I didn't want it flopping around inside the case. So I modified the case to have a pocket that fit the battery, designed a battery strap to keep the battery from coming out of the pocket, and added holes for heat-set inserts in the base to screw the battery strap into.

Files both with and without the battery pocket are included. Both files have the heat-set inserts for screwing the CurrentRanger to the case. My .FCStd files are included as well, so you can use FreeCAD to modify my remix to fit your needs, especially if you have a similar, but different sized battery you'd like to use.

Printing Instructions:

• 4 perimeters (to give sufficient wall thickness for inserts)
• Print external perimeters first (for better hole dimensional accuracy)
• 0% infill (infill isn't required for a successful print, but there's no downside to having it)
• Avoid crossing perimeters (not needed, but helps reduce any stringing)

Print with the open part of the case facing up.

Assembly:

You may need to modify the source file to get the proper hole ID for heat set inserts. What I did was order a 3.2 mm drill bit from McMaster, so slightly undersized holes could just be drilled out to the proper size and I wouldn't have to mess with print settings every time to get the right hole size. I highly recommend this approach, it saves a lot of time!

Generally, the ideal way to install heat-set inserts is to purchase tips for a soldering iron. Ideally, you have a temp-controlled soldering iron. I have a Hakko FX-888, and if you're looking for a better soldering iron, here's your excuse. Get the Hakko FX-888D and it'll be the last soldering iron you need for hobbiest work for the rest of your life. Lacking this, I've read it's entirely possible to install with a non-temp controlled iron with a regular soldering tip, just a bit harder to do.

CNCKitchen recommends that you install the insert 90% of the way with the soldering iron and use a flat object to quickly press in the insert until it's flush. Especially with a dedicated tip and temp-controlled soldering iron set at 225 °C, I found I can get away with inserting them flush directly with the iron. Except for the case with the battery strap, the iron would be at a slight angle or it would hit the wall of the case. Here, I had to stick to pushing them in at a slight angle to 90% or so, then using a flat object to quickly press the flush, which will straighten them.

Remix History:

Andreas Spiess (spiessa) created the original case, which lowpowerlab remixed into the CurrentRanger enclosure. I actually downloaded the CR_R3.step file from CurrentRanger's GitHub, because the one CurrentRanger had on Thingiverse was only an .stl file. Presumably the one on GitHub was the same remix on Thingiverse, just with the original source files. There's also a .f3d file over there, but FreeCAD, which I use, cannot load a Fusion360 file, which is why I used the .step file as the base for my remix.

Two different modifications:

1. Screw holes for screwing PCB into case were changed to square “posts” that have 3.2 mm ID holes for M2 heat-set inserts.
2. Added a raised profile on the base that securely holds an Adafruit 1200 mAh, 3.7 volt lithium battery. Created a battery “strap” that screws into heat-set inserts in base to keep the battery in the pocket.