I have a hanging potted plant for which it is difficult to check the moisture level. I want to use a pulley system to create a sort of "scale" which gives a visual indication of the relative dryness of the plant.
Currently I have a fixed pulley setup: the plant is 5lbs, and I have a 5lbs counterweight hanging on the other end. The counterweight is 3" off the ground. Theoretically, once enough water evaporates from the plant, the counterweight will touch the floor, signaling that the plant is ready to be watered.
My main concern is about friction -- is the difference between a wet/dry plant enough to overcome the static friction? I am keeping my eyes on the situation, but it hasn't moved yet.
Now I'm thinking about other approaches using block & tackle to make the system more sensitive.
For instance, a gun tackle has an advantage of 2. It seems that I could use this to double the mass of the counterweight. Am I correct in thinking that more weight in the system will make it easier to overcome static friction?
Alternatively, it could be set up the opposite way where the counterweight is half the mass of the plant. This would magnify vertical movement of the plant by 2x, possibly leading to more prominent visual feedback. Yet the system becomes lighter, which seems like it would hinder its ability to overcome friction.
Does any of this make sense and is there some better method?
Those are 3" pulleys with ball-bearings; smoother than the last 3/4" ones. The cable is 1/16" steel.
The difference between moving reliably in one direction vs. the other is approximately 150g.
The pot holds approximately 2L of soil. A quick search suggests a normal watering might be around 20% of the soil by volume. It's possible a pot without drainage needs less, say 10%. That would be a delta of about 200g, enough to move in either direction confidently.
However, after removing the extra weight (all on the plant side), it gently slid up until the counterweight touched the ground. It had been at rest for a few days. I guess this means static friction increased over time until playing with it loosened it up.