Printed on Lulzbot Taz, ABS, 0.22 layer height, no support, 30 to 40 % infill. Make sure to use ABS that is bright white to minimize absorbed solar radiation. We used ABS from Ultimachine, https://ultimachine.com/. Some sources of white ABS will become slightly off-white after printing. In such cases you could spray paint the parts bright white. We had success with Rust-oleum Painters Touch 2X Ultracover paint+primer, gloss white).
Tap top section for 10-24 threads
Install all-thread for vertical support, 4 or 4 1/8 inches long each, 10-24 thread
install base plate with 10-24 nuts. Note, install M5 or 10-24 set screw on base before mounting
add mounting bracket, with additional 10-24 nuts, could use jam nuts here
after soldering wires to HTU, clean solder pads with alcohol, apply epoxy over solder joint only
Install sensor (Adafruit's HTU21D-F humidity/temp breakout secured to mount with sm zip-tie.)
install sensor, do not over tighten set screw on side of base
UV coating, wiring, weather protection
Before assembly spray all printed parts with a UV resistant clear coat. Krylon fusion. ( recommended for long-term deployments) http://www.amazon.com/Krylon-2444-Fusion-Plastic-Clear/dp/B001TNMWBM
For signal wire on the HTU sensor I used round 4-conductor solid-core telephone wire purchased at Lowes. (RCA 100' 4-Wire Round Station Wire Cord - Almond
Item #: 82473 | Model #: TP004R)
After long-term exposure to the weather, we have noticed corrosion and residue at the solder pads/joints where the signal wires are connected.
To reduce corrosion, make sure to clean the solder pads on HTU sensor with alcohol after soldering. I coat the solder joints/pads on both sides with 5-min epoxy (Devcon, clear). Apply the epoxy sparingly, only where the signal wire is connected the the board - leave the remainder of the board on-coated.
Instead of using epoxy on the solder joints, you could also coat the whole board with silicon conformal coating. Make sure not to get any silicon on the white white plastic PTFE filter on the RH sensor.
Software / Code