Curtain Motor Recomendation - Are there external "Addon Winder"?

Hardware
#1

Hey there, i’d love to automatically wind up/down two Curtains.
They don’t have a classical “Belt”, its more a Rope. The Winding (where the unused Rope rolls in) is in an external enclosure, which can’t be openend. On Top - our Flat is for Rent, so i can’t drill/dig a lot, best Case not at all :smiley:

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I was wondering if there is a Device, where i could attach the Winding Motor Outside (= inside the Room), pull the Curtain down, and clamp/fix the Rope - and then just let it wind the Rope inside.

Basically something like the Aqara E1 Roller Shade Driver would be perfect - it is chargeable, has definable start- and endpoints, works with Zigbee… but i doubt it is powerful enough, and it is only working with beaded Cords anyway.

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So - is there a Device i could use for my Roller Blind/Shade?
Do you think, when using a DIY-Adaptor with e.g. 5:1 winds, the Aqara could be powerful enough?

#2

The SOMA Smart Shade v3 can easily pull the required weight. But it only really supports looped cords. I’m sure a wheel could be printed where you could wind cord onto the wheel itself but then there would be a limit to the amount of cord that can fit before the spool becomes too thick and starts binding. If you have to pull hard (with heavy curtains) any non-drilled mounting system will more than likely fail eventually. Or of it really does stick that well it will probably be impossible to remove without destroying the wall.

1 Like
#3

That is a really cool Idea!
Do you have such a Device on your own? If so - is there a Kind of Lock when it is not working? If would go for such a Solution, there will be permanently 7kgs be pulling… :frowning:

#4

I have two. I’m one of the founders of SOMA and this is our newest motor. It doesn’t really lock in any way in the current configuration but if you want I can try it holding 7 kg next week. The gearbox has a worm gear in it which makes it pretty hard to back drive the motor. We did test it with enough weight to make it slip eventually but I’ll have to find out how much weight that took. This is only possible because the current motor is configured more for speed as most shades would not require that much torque. But gearbox supplier can actually make almost any configuration including ones that could easily hold much more weight than 7 kg.

We’ve only tested the spooling wheel kind of like a joke so far. It has some characteristics that make it a bit difficult to use in practice and there don’t seem to be a lot of people that need that specific configuration. If you really want to try that let me know next week and I will talk to the mechanical guy who ran these tests. We may have a printed prototype of that spooling wheel.

How long is the curtain you want to move? I man how long is the piece of string that has to wound on the spool and how thick is the string?

1 Like
#5

Yes, maybe you made the right Decision by not focussing on that Market, as i couldnt find anything similar. Or totally wrong as it would be the only one :wink:

Well sure, if it isn’t too much effort, it would be great if the Worm would reliable hold 7kg!

On the other Hand, i am not sure how confident i will be in the End, eg. if the adaptering Ball-Chain would be strong enough for 7kg, approx. 300 Days/Year (Thats roughly the Time the Curtain will be up…
Maybe i would need to look for a (Kind of) self-locking Spindle anyway.

Regarding the Spooling - the Cord, better said the needed Distance, would be around 120cm, beeing 5mm thick. So i think i would look for a larger Spool, to have less woundings.
While i really would love to have a set-and-forget solution, there is really no Rush for me to find a Solution. Holidays right now :wink:

In the End - Interesting Project i would love to install someday, really appreciate your Effort!

#6

I would love to support all the weird things people want to do and build. I actually got into this business because I had a need for something like this myself.

If you want to build something yourself and have it automatically self lock all you really need is a high ratio worm gear. Any worm gear with a lead angle less than the arctan of the friction coefficient will be impossible to backdrive. If speed is not an issue for you just get a gearbox with a ratio of something like 150:1 with a worm gear. That will most likely be impossible to backdrive without destroying the gears.

But remember that if you use a larger diameter spool the torque on the gearbox output shaft will increase. Basically that is just like another stage of “gearing” for the whole system. SO you probably want to make the spool as small as possible to fit the cord but not much larger. If you need to you should probably make the spool longer instead of making the diameter larger. But if you make it too long and only support it from one end (the gearbox output shaft bearing) it will start to bend and that will again be bad.

This is mechanically an interesting problem but if all you want is to build one for your own use you can just use a really big and strong gearbox and not worry about the actual calculations.

If there is enough slack in the cord maybe you can build some kind of counterweight system to take off most off the load and still use a small motor for this. Even the Chinese one you linked will be able to lift a few Kg if the rest is balanced by the counterweight. In that case you probably need to build a kind of pulley system there which could be difficult if you can’t drill into the wall.

Happy Holidays to you and good luck with the project. Solving problems like these is why this community is so awesome in the first place.

1 Like
#7

Totally agree! And this Input is really awesome. I had no Idea about that Worm Gear. This is really great. And yes, Speed isnt the most important Thing.

It is obvious that you know what you are talking about. I will think about that Spindle-Thing - as small as possible, as big as possible, as long as possible, as short as possible :smiley:
There might be a possibilty, to not only drive the worm Gear, but a guide as well, to let the Rope go around the Spindle.
Yes, that got me :slight_smile:
So - you would say going for a worm gear with a big Ratio shouldnt be a Problem for the Soma, right? Are there Specs, by whom i can tell that Soma and Worm Gear should be working together, e.g. nm or kg?

Thanks again for all your great Input, highly appreciate it!