Drip Governor - A most valuble first hack

[rylangrayston]

Wow

great work everyone!

ok so in testing the design i had posted last we have found some major problems.
It did work great for a short time here are a list of problems we had:

- it got gummed up by resin and or salt
- it required about 400 mA to work reliably ( way to much power)
- its rather large
- the relays in the circuit combined with the coils were creating a very strong radio wave ( from the spark gap ) and
caused the serial port to time out! (ugg this took a while to figure out!!)

We are just attempting to do some larger prints and so this drip governor could be really valuable to that end.
So me and Erik took some time the other night working on new hardware for this hack

Erik has one that's almost done hopefully he will post some pics of it here tonight.

I went into my head for a few hours and came up with a design with the following features in mind

- much lower power required ( more efficient use of the magnetism )
- super easy to take apart and clean
- easy to make with a stack of rings cut out by the laser cutter
- moving part needs to be guided very well
- very small and inexpensive in volume
- use power mosfet instead of relays ( works great!)
- move to an H bridge, revesing polarity on the coil.

here are my blend files and i wipped up another animation ...
https://github.com/Rylangrayston/Ran...drip%20govener





My next step is to make this same design in open s cad, with the intention of cutting it out of a stack of disks and rings on the laser cutter.
if that docent work well I may just make it on my metal lathe for now.

Speaking of which dose anyone here use open s cad ?
We could alwase use help coding highly parametric designs !
esp for hacks like this.

@Pete
I thought the salt water was better because it was more conductive .. tell me more! What is it about salt that makes the pulses better!
although i must say this topic may need its own thread. Also yes your on to something ... we have noticed that the size of a drip grows by 30 percent
as the drip frequency goes from 1 drip per second to about 5 drips per second. We doubt that this is linear and it needs much more testing before
we can do a good job of accounting for it. luckily we know the drip frequency, and if the frequency stays the same then the drip size is very stable.
so it looks like a very solvable problem.


@Anuvin
great stuff, if i make one on the lathe ill def use your lego casting idea to make a few more!! very cool, plus its something i can do with my son
Any thing to do with lego and he is in! I think if we made a Lego spoon he would eat broccoli with it lol.

@Mike_Biddell
So simple, just love it, how about using a power mosfet to replace the transistor you used and then also adding a capacitor to its gate so when the switch gets a short pulse of light
it charges the cap quickly which holds the mosfet on for a few seconds. That way the peachy can ask for say 10 drips at a time, and spend very little time on the LDR.