Use of thread locker isn’t a requirement, it’s more of a personal preference thing. Using it has two potential downsides: first, it can be a hassle if you’re constantly taking things apart and modifying them. Second, the HDPE material of the BROV frame tends to compress a bit over time, so you may find that screws that were tight when they were locked in place are no longer tight after a while.
Here at Mission Robotics we skip the thread locker altogether and use a thread lubricant called Tef-Gel, which is a combination (I believe) of silicone grease and teflon. The grease acts as a water barrier to prevent galvanic corrosion, and the teflon helps to lubricate the joint should some corrosion occur.
We started using this when we noted that there was galvanic corrosion in many places on the vehicles where stainless fasteners are threaded into aluminum.
Tef-Gel obviously doesn’t provide any thread-locking function, and every couple of months we’ll go around and check the tightness of screws that are clamping HDPE material. But that’s something you probably ought to be doing even if you did use threadlocker.
You can find Tef-Gel on Amazon. It’s pricey but a small tube should last a lifetime.
We specifically recommend a medium strength option, that’s designed to improve the screw stiction once installed, but still be removable with hand tools if and when disassembly is required.
It’s perhaps worth noting that the parts we suggest using threadlocker on are also parts that can often remain screwed together when performing maintenance on the vehicle.
No threadlocker makes it more likely that vibrations will cause assembly or frame rigidity issues over time.
Yes, you’ll just need to be more diligent with checking the tightness and seating of your screws on a regular basis.
@nfored we have a threadlocker recommendation in our assembly guide (as linked above), but as far as I’m aware it’s not PC safe. Threadlockers in general don’t play nicely with many plastics (including acrylic and polycarbonate), so we generally recommend against using threadlocker on screws that are in contact with polycarbonate parts on the vehicle unless you’ve sourced one that explicitly specifies it’s PC safe.
@EliotBR Can you comment on if HDPE is it safe with the blue locktie you linked, only planning on using it on the HDPE frame don’t want put it on the tube itself unless there is a good reason. If I understand @wholm when I get the HDPE bolts tight after some time the HDPE will change shape slightly and I would need to tighten the bolts again but blue locktight should be able to broken with hand tools.
I have coaxial octocopter I got a bit lazy one flight and didn’t do a precheck and got to see what happens when a motor spins off the arm :-), no amount of redundancy makes up for a motor and prop fling around the frame like a wrecking sword. Needless to say I check now.