Hence flexible couplings!
Max.

 

Thanks Max, agree and will do. The thing is I need to align it anyway because even flexible couplings will only flex so far, but also I need to make sure I can find a flex couple the size of my blind tube.

 

The thing is I need to align it anyway because even flexible couplings will only flex so far, but also I need to make sure I can find a flex couple the size of my blind tube.

Which is why I suggested making the motor mount into the blind bracket in your other thread. That way everything is in line and happy. Once you put more than one thing into the mix you need to have either precision alignment(in many directions in this case) or a chain or pulley between the motor and the driven device. When the motor is part of the device the alignment is assured.

 

How could I make the motor mount part of the blind bracket? The motor mount is the black bracket and the blind bracket is a white piece onto which I highly doubt I could mount anything onto given its so small.

 

OK I think I figured out why it's not rolling up. I thought it wasnt level because I measured about 1-1.5cm difference from the tube (since the curtain became un glued) down towards the top edge of the window frame


But it turned out to be an optical illusion. The room might not be a good cube so the window isn't framed quite right. So I used a level on top of the tube and it's pretty level.

I ran it a few times and I think the problem is the shaft-to-coupler connection might not be tight enough.

They didn't do a good enough job with the hole in the coupler so the shaft might be spinning around inside the coupler hole. What do you call that BTW?

 

After more thought and trials, I actually don't think it's the coupler-to-shaft connection. It just seems the motor has a hard time starting up. So in essence it just might not be powerful enough.

 

They didn't do a good enough job with the hole in the coupler so the shaft might be spinning around inside the coupler hole. What do you call that BTW?

Looks to me like the motor is turning but the coupling is slipping?
Definitely needs a proper means of positive coupling.
Max.

 

Didn't you put a set screw in your coupler? Even press fit couplings need to have at least one set screw, most have two at 90 degrees from each other.

 

Hello,

Here is an example of the set screw:
https://www.alibaba.com/product-detail/Types-of-Flat-Cup-Cone-Point_60006997866.html

Bertus

 

No I didn't. Where would it go? But I honestly don't think it's the shaft slipping inside the coupler because I would see the shaft spinning right?

 

Hello,

Here is an example of the set screw:

Bertus

Or in UK-speak, a Grub Screw.
It looks to me as the shaft IS spinning?
Max.

 

Yes the shaft is spinning, but when it spins so does the tube, and when the tube stops so does the shaft. So it seems the coupler is working.

 

It just seems the motor has a hard time starting up.

It certainly looks like it, with you giving it a bit of assistance. If startup is hard without the blind material on the roller (as it appears in the video), then its likely to be impossible to raise a fully-lowered blind. A bigger motor, or reduction gearing, is called for IMO.

 

Agreed! It's a 0.23 Nm so Im looking at 0.4Nm.

 

Is the far end of the blind on the same plane as the drive/motor end?

 

No...good point ‍. Makes sense that it is level on 2d but not on 3d!!!

 

If it is out in any plane there will be a drag on the whole drive.

 

Ok what torque would I need for this curtain? I dont have a torque-measuring tool.

 

You can estimate with weights and a lever of some sort. Say units are oz-in your looking for.
Make a lever that is 1" and tie a 1 lb vegtable can to it. Will it rotate the curtain. if so, then that's 16 Oz-in,

If the lever was 2" and the weight 8 oz, then 8*2 or 16 oz-in.

Find a convienient weight.

You can also use a light container. 1 cc of water weighs about 1g. Do all of the other conversions.

there is some weights for coinage too, that you can use for estimation.

When you make your lever, put holes in various places. e.g. every 1/2 inch.

It's likely under 50 Oz-in.

 

Really looks like the motor is just stalling- not enough torque output to turn the roller.

Squeezing the most out of a stepper requires precise acceleration of the motor pulses, and careful avoidance of certain RPM's where there can be torsional resonance that eats the motor's power. A sure sign of resonance is when the motor starts, runs, then stalls while moving at a constant speed.

Try playing with the acceleration profile and the top speed.