Opening and Closing Vents Using Motors

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21

Thanks Michael (and Bob)

I think the FS90MG (SKU: CE09378) might fit the bill nicely. My printer should arrive in the coming week so what I’ll do is print a couple of flaps, then weigh it, and then order the servos once I’m sure of my numbers (remembering that I will be opening the flaps in pairs, so twice as much weight.)

Cheers

Russ

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22

Hi Michael
I waited for my 3D printer to turn up, put my design through the slicer and THEN found out that the slicer tells me exactly what the finished model should weigh. So, I didn’t have to wait for the printer to arrive anyway…

Anyhoo, the finished flap (after three modifications) weighs just 42 grams in total. I will be swinging two flaps at once, so I’m thinking I should go for the FS90MG (SKU: CE09378) which apparently has a torque of 2.2kg/cm. Any thoughts on this? I need nine of these for this job and another couple for a warm air recirculation system for Winter, so I definitely don’t want to be ordering the wrong ones.

Cheers

Rusty.

23

Nice, @Russell106934 :slight_smile:
It seems like a reasonable weight, though the lower you can get it the better!
I don’t know what will be best at this point - it’s an integration challenge.

Will the weight sitting on the gearbox alone be enough to bind up the gearbox over a long period? I don’t know
Will the servo have to constantly fight the weight of the flap - heat up and eventually burn out? I don’t know

It’s all an experiment from here. Of course you can spec up your servos if you want to be conservative.

Nothing beats a low-stakes empiracle test. Is it out of the question to try it out at a small scale before committing?

24

Thanks, Michael. I spent several hours nibbling bits out here and there, in an attempt to lighten it some more (I had already done away with the double-sided version, going for an open-frame style) but I only managed to remove another two grams…

Anyhoo, I’ve ordered one of those servos and an ESP32 so that I can do some tests.

Thanks for the help.

Rusty.

25

Hi Michael
Boy, have I learned some stuff. The ESP32 (C3, RISC) did not play nice with ESPHome (initially) but after using the Espressif app, I got it going. Then I found that the servo only traveled 160 degrees, instead of the 180 degrees and I had to dig in to the bowels of ESPHome to find out about min_level, idle_level and max_level settings.

Then I found out that the entire assembly flexed too much to allow the vent flaps to pull tightly shut against gravity, requiring a rethink whereby I now will mount the assembly far enough below the air exit point to allow the flaps to open against gravity (which they do with ease) and close with gravity. Not to mention learning a lot about 3D design so that I could print an adapter that goes between the servo and the flap axle, and a mounting block for the servo motor assembly.

Anyhoo, all good and the servo copes well, so I will now order the qty I need for the job. Thanks for all of your help.

Rusty

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26

@Russell106934
How good Rusty! Projects that move are easy to describe but often the devil is in the details. I’m glad you prototyped out a solution.

regarding flap weight etc - remember that you can always include a little counterweighting to the servos to lighten the torque so the servo doesn’t have to work so hard.

I’d love to see a progress shot of what you’re working on :smiley:

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