Turning a rotary knob with stepper motor

[namlu]

Hello.

I want to turn a rotary knob of a test equipment with a small stepper motor:
https://www.google.co.il/search?q=rotary+knob&client=safari&hl=en&source=lnms&tbm=isch&sa=X&ei=HafBU_m_N6jG7Abu4ICADg&ved=0CAcQ_AUoAQ

It is about 2 cm in diameter.

My question is: how do I hold it with a stepper motor? How could it be attached?
Any idea? Is there any known thing I can just put on top of a knob and attach it to the motor?

Thank you.


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[BillWojo]

Do a search for shaft couplers. You will need to know the diameter of each shaft.

BillWojo

[rob77]

+1

don't even think about trying it without a shaft coupler ! you would kill the sensor (pot, encoder...) attached to the knob. the shaft coupler is a must to absorb any misalignment between the shafts. btw.. i'm talking about misalignment in orders is tenths of a degree or tenths of a millimeter off-center... so you have to "perfectly align" even when using a shaft coupler.

[Stonent]

If the encoder clicks between positions you'll also need to make sure the stepper and encoder have the same number of clicks per rotation if you need to accurately set a position. 

Optical encoders like the ones used on ball mice do not click.

[elliott]

A piece of rubber hose works pretty well as a coupler for low torque applications.

[namlu]

Hello guys.

Thank you for your tips. After looking in ebay, I ordered rubber hose:
http://www.ebay.com/itm/221234449225

The size looks good and it actually may work.

I will wait a bit with shaft couplers.


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[DavidDLC]

Hello.

I want to turn a rotary knob of a test equipment with a small stepper motor:
https://www.google.co.il/search?q=rotary+knob&client=safari&hl=en&source=lnms&tbm=isch&sa=X&ei=HafBU_m_N6jG7Abu4ICADg&ved=0CAcQ_AUoAQ

It is about 2 cm in diameter.

My question is: how do I hold it with a stepper motor? How could it be attached?
Any idea? Is there any known thing I can just put on top of a knob and attach it to the motor?

Thank you.


Sent from my iPhone using Tapatalk

I'm interested to know why do you want to do this. Can you explain ?


David

[namlu]

Hello.

I need to go through the entire scale of an old test equipment, in order to debug a FPGA design. It takes about 10 minutes each time. I hope to do it automatically.


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