Servo motor gets stuck at a certain point

I bought a 180 degree Servo but on rotating with my hand found it to only rotate 90 degree.

After the initial disappointment I still used it with an arduino UNO and I found that there was something jamming the gears at the 90 degree mark, so sometimes it would just jerk and continue rotating and sometimes it would just stay there.

I identified a small particle(not very clear what) at that column in the gear that caused it to get stuck.

How do I take it out without damaging the Servo in any way?

So you have an unidentified servo which you have opened up and found an unidentified small particle somewhere inside. Maybe a bit more information, perhaps some pictures, would help. At the moment all I can suggest is that you take whatever it is out VERY CAREFULLY.

You can get complete replacement gear sets for some servos so perhaps that might help.


Thanks for the reply!No I didn't open it up. I have a micro servo. Through the translucent blue surface I could see that the particle was causing problems. However is it advisable to open it up and clean it?

Be careful rotating the servo by hand. It is easy to damage the gears doing so. Gentle and slow may let you turn the servo by the output arm without damage.

servo and micro servo do not tell us much. What is the model of the servo? Can you post a pic of the servo? And a link to where you bought it?

If it is not an economic hardship, buying a few spare servos is always a good idea. Servos fail. More so with cheap micro servos.

Some servos have a hard stop built in to the gear train to prevent over-rotation from damaging the internal potentiometer. Maybe that it the item you see in the gear train?

Most servos can be opened to access the gears. Most have 4 small screws. Remove the output arm and the 4 retaining screws. This will let you remove the top and access the gears. In my experience, they can be removed, inspected and replaced without additional tools.

There will be grease on the gears. Try to avoid wiping it off.

Cheap servos are not 180 degree. Typically you’ll see 120 degrees or so, but it does depend on the model
and manufacturer.

These are cheap components made for toys, not precision engineered unless you select one designed
expressly for robotics.

But you haven’t said which servo you have so its impossible to say if its actually designed for 180 degree travel
or not.

I don't think it's a problem with the maximum possible rotation because on using it with a battery and arduino I get the full 180 degree with a jerk at the 90 degree.

I'm not sure about the exact model but here is the pic of the servo and the particle I see causing problems( in the attachment)

I am going to go out on a limb here and guess that you have a Tower Pro SG90.
Because that is what is printed on the servo
:stuck_out_tongue: :stuck_out_tongue: :stuck_out_tongue:

That is an instructable for modifying a servo. I am not suggesting you modify yours. But it DOES have a decent pictorial on opening up the servo. Then you can tak a pin or needle and remove the debris from the gear teeth.
Reassemble and you should be good!

Haha I’m kind of a noob so I didn’t even read what the label said . But thank you so much for bearing my amateur problems!