Stepper motor brake

Thread Starter

giedrius15004

Joined Jul 18, 2022
7
Hello,

I am searching for a solution how to prevent stepper motor from moving while it's inactive. Is there a model that has this feature that I have not found? Is there an additional brake which would be placed on top of moving part? Is there some kind of DIY solution for that?

I have roller blinds which now are connected to stepper motor. It works just fine, but when it is rolled down quite a lot, motor starts to move due to weight of blinds fabric.

I would be willing to use other kind of motor if it would have brake feature. Could anyone help me out?
 

Ian0

Joined Aug 7, 2020
5,814
If you are looking for an electronic solution, then just put a small amount of current through the motor; but it’s not an efficient use of energy.
 

Thread Starter

giedrius15004

Joined Jul 18, 2022
7
I would prefer mechanical solution which would lock motor in position without current and release it when power applied because in case power blackout or simply maintenance of the system, blinds will roll down and will have to recalibrate it.

Thank you both for the ideas, I think I will try finding more about worm gear type reducer.
 

Ian0

Joined Aug 7, 2020
5,814
Depending on the stepper motor and the weight of the blinds, shorting all the terminal of the motor together might stop it.
 

Thread Starter

giedrius15004

Joined Jul 18, 2022
7
If you're handy with mechanical things you could make a solenoid mechanism which blocks movement when unpowered but allows movement when powered.
I was thinking about it. Have seen this video where this solution was made:
But before trying it, I was interested if there would be some kind of specified brake or something. Solenoid might be best solution in this situation I guess.

Thank you for a comment.
 

Thread Starter

giedrius15004

Joined Jul 18, 2022
7
Depending on the stepper motor and the weight of the blinds, shorting all the terminal of the motor together might stop it.
I will test it out, but I am not sure how it would be possible to realize shorting them and then re-shorting for normal operation.

Thank you.
 

Ya’akov

Joined Jan 27, 2019
6,260
A relay, energized any time the motor is runnig that used the NC (Normally Closed) contacts to short, and the common for the stepper though the NO (Normally Open) contacts should work.
 

Thread Starter

giedrius15004

Joined Jul 18, 2022
7
OK, nice, shorting all contacts does make it rotate less (needs more strength to rotate it).

And good point about relays. Did not thought about it. Although I had similar situation with relays where I needed to use this kind of "switch" but with lights automation. Thank you, Ya'akov.
 

Ya’akov

Joined Jan 27, 2019
6,260
OK, nice, shorting all contacts does make it rotate less (needs more strength to rotate it).

And good point about relays. Did not thought about it. Although I had similar situation with relays where I needed to use this kind of "switch" but with lights automation. Thank you, Ya'akov.
Don’t forget you will need to keep make sure there is no connection from one winding to another when the relay operates. This means a contact for each wire that switches that wire between a shorting bus and the controller output. For a four wire motor that would be a 4PDT relay.
 

Thread Starter

giedrius15004

Joined Jul 18, 2022
7
Don’t forget you will need to keep make sure there is no connection from one winding to another when the relay operates. This means a contact for each wire that switches that wire between a shorting bus and the controller output. For a four wire motor that would be a 4PDT relay.
Yes, I am aware of it. Thank you.

Just tried blinds with stepper motor with shorted contacts and... it rotates.. Blinds are too heavy. So I would probably try to use solenoid this time.
 

MaxHeadRoom

Joined Jul 18, 2013
25,623
I would prefer mechanical solution which would lock motor in position without current and release it when power applied because in case power blackout or simply maintenance of the system, blinds will roll down and will have to recalibrate it.

Thank you both for the ideas, I think I will try finding more about worm gear type reducer.
As mentioned, a worm and pinion arrangement cannot be back fed/rotated by an overhauling load. i.e. power removed.
The other common way, also mentioned, is to apply the constant current at the plate rated value.
 
Last edited:

MrChips

Joined Oct 2, 2009
26,774
I vote for a worm gearbox. This is self braking. You cannot turn against the motor.
Can you post information on your stepper motor or post photos?

A stepper motor with gearbox does not come cheap.
A lower cost solution is to use a DC motor with a gearbox and use limit switches to stop the motor.
You can buy DC motors and gearbox with rotation encoders but this will make your solution more complex.
 

MisterBill2

Joined Jan 23, 2018
12,676
I use a powered "dolly" to move a travel trailer and the driving gearmotor came with a spring applied brake. similar brakes are often used on hoists. A suitable spring applied brake for a stepper motor might be available.
One other idea, purely mechanical, is a low-torque brake connected by an over-running clutch, so that it takes a bit more torque to lower the blind. but it is disconnected for raising the blind. That option would attach at the lowering drum so it could be a simple add-on. Ihave seen adds for exactly that sort of package, but not recently. Quite possibly the simplest option.
 

MaxHeadRoom

Joined Jul 18, 2013
25,623
One common way of maintaining zero position with a stepper motor is to maintain plate rated current at all times, , not only when running but when stationary,
Providing this braking torque is sufficient for this particular load.
 
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