I have this curtain that I want to interface to a stepper I can Control electronically. Are there specific adapters for this?

 

What is the spec on the stepper motor?
What is the required rpm?
How do you want to control it?
Max.

 

I haven't thought of the motor but was thinking of using a run of the mill:

http://www.tinyosshop.com/index.php...n=true&filter_sub_category=true&product_id=82

But I'm wondering about the adapter

 

But I'm wondering about the adapter

There are many to chose from out there, (Gecko etc) unless thinking of putting your own together.
Max.

 

I have used this one and like it.
All it needs are step and direction signals.
Stepmotor Driver 3.5A
Item #: 32383 MS
Sale: $19.95

You can set the output current.
There are a few more on that site.

 

No...sorry I wasn't clear. I meant how to connect the actual shafts of the motor to the curtain mechanism?

 

No...sorry I wasn't clear. I meant how to connect the actual shafts of the motor to the curtain mechanism?

Since it is already using a 'ball chain' the easiest would be a ball chain sprocket to fit the motor - http://www.raymortool.com/SprocketPages/SprocketIndex.htm

 

If it is not intended to be motorized or mechanical driven, then you will need to do some custom engineering, such as fitting a shaft to the blind and using flex couplers etc.
Gearing may also be needed depending on the torque required.
Max.

 

such as fitting a shaft to the blind and using flex couplers etc.
Gearing may also be needed depending on the torque required.

That's why I suggested the sprocket. Many people think, "oh, it just needs to be somewhat close and I can put a flex coupling on it", but that doesn't work in the real world.

 

As the coupling that joins the ends of a bead chain will not pass over the bead sprocket the two sprockets would have to be far enough appart so the coupling did not have to pass over a sprocket. I agree with Max that you will probably have to make your own coupling. This is the thing I made to drive a roller blind which had a similar bead chain to your curtain.

The rear of the bracket on mine has a square shape to fit into the origin fixing bracket.
My system just counts revolutions of the gear wheel with a reflectve opto sensor mounted on the small piece of stripboard on the bottom corner of the bracket.

Les.

 

Thanks guys.

LesJones, what do you mean by:
"As the coupling that joins the ends of a bead chain will not pass over the bead sprocket..."

So you mean there is no coupler that will hook up to the stepper shaft and then to a nylon sprocket?

 

Usually if it is not really designed for external drive, then you would need to come up with a custom design, i.e. design a custom shaft or other means of driving the sprocket and adapt as needed.
Max.

 

The problem with the chain coupling not passing over a sprocket is with reference to shortbus's solution. ( as this will use a sprocket on the stepper motor shaft similar to the one on the end of the curtain drive.) The two sprockets would then have an endless loop of bead chain passed around them. I dont thing that you will be able to buy a bead chain sprocket that fits directly onto s stepper motor. You will probably have to adapt one similar to the one on your curtains. If you look at this link to "roller blind spares" picture 8 shows the item that joins the ends of the bead chain together. Picture 1 shows a drive sprocket assembly and a bead chain with the ends joind together. As Max has said you will not find a ready made item to connect the stepper motor to your curtains.

Les.

 

I'm sorry I misunderstood how it worked. I thought the (red arrow) item was what I had to turn, but in reality I would need to take out the metal plate (green) and see what I have.



So under that plate I'll probably find something like this on either side. The red is the one with the bead chain, which I would need to replace? So one option would be to replace that red circled connector with a coupler to the motor?

What about the green circled one? Is that also an option?


OK so I would have to build that coupler or buy it?

 

The green circled item is the bearing that supports the other end of the roller blind. Both items are probably a push fit into the aluminium or cardboard tube that the blind is rolled on to.

Les.

 

OK so I'm still not clear how to make the coupling. I took part the ends and saw this:


So what turns on the chain side is the outer (red) bead-sprocket and the middle (red) aluminum tube fitting and what doesn't turn is the inner green part which is where the wall bracket is connected to, right?

 

So I would have to make something like this:


Where the blue aluminum tube and the green nylon insert are from the original curtain itself. I would have to rip off the end on the green nylon insert that has the sprocket and make the red-ochre coupler for the shafts of the yellow stepper...and somehow make it so that can all be bolted to the wall.

 

Try going to your local rubbish tip and pick up a couple of old printers, they contain a variety of useful gears and motors etc. You could drive the bead loop by using the small rubber rollers used in printers to feed the paper though. sandwich the loop between two rollers spring loaded together, drive one with the geared motor and it will pull the bead loop through. just provide a couple of cheeks either side of the rollers to stop it coming off.
Should not be too difficult to cobble up from the printer parts, + you will find optical rotation position sensors in there too.
Saves you having to mess with the roller blind support.

 

In post #16 at the bottom of the right hand picture you show the existing sprocket on the blind with the beaded cord passing round it . You would mount a similar sprocket on the stepper motor shaft. The beaded cord would also pass around that sprocket and the ends of the cord would be joined to form an endless belt. Think of it like the timing chain (Or timming toothed belt that seems to be more common these days.) on a car engine that drives the camshaft from the crankshaft. The only difference would be on a car engine the sprockets have a 2:1 ratio of the number of teeth. The system suggested would have the same number of teeth on each sprocket. Because the joining piece on the cord will not pass over the sprocket the sprockets must be spaced far enough appart so that joining piece does not have to pass over a sprocket for the required travel of the blind.

Les.

 

Thanks les but I think I wouldn't need a bead chain in my idea. I want to connect the stepper directly to the aluminum tube via some kind of coupler as drawn in Post 17