user16723: I'm looking for a limit switch to use with the Arduino. In my project I want to count how many times my turntable makes a full 360° rotation. An object (wheel, pipe, whatever) will be sticking out the side of the turntable and when it comes in contact with the limit switch that will be right next to the turntable, it should notify the Arduino.
Any suggestions on which limit switch I should get?
Thanks so much in advance!

user3557: Instead of a limit switch a hall effect sensor with a moving magnet is an optimal soltuntion since it is contact less there will be no frictional side effects on your application.
But there is one more better way to it, try to use an rotary encoder, something like a 400/600 ppr should also be fine for this, doing this way you have more positional data of the turntable, 
You can calculate no of turn, arcs etc.
For eg: 

A 400ppr would give you a resolution of 0.9 degree per pulse, and 
600ppr would give you 0.6degree per pulse of accuracy.

Although you can go for even higher ppr encoders but you can get these at very low cost. 
Pic from: https://m.ebay.co.uk/itm/400BM-Rotary-Encoder-Module-LPD3806-360-6mm-Shaft-Arduino-Pi-Flux-Workshop-/112607725039?_mwBanner=1 
Note: Just an example, price may be different at other webites, haven't checked the price while writing this solution.


user6628: A $2 microswitch with a roller would be OK for a million revs or so.

You would put a little ramp on the diameter and use it to trigger the switch.
Non-contact magnetic or optical could be better for more cycles or faster operation.

16723: <p>I'm looking for a limit switch to use with the Arduino. In my project I want to count how many times my <a href="http://cdn.shopify.com/s/files/1/0220/4654/products/slider1_large.jpeg?v=1420208854" rel="nofollow noreferrer">turntable</a> makes a full 360° rotation. An object (wheel, pipe, whatever) will be sticking out the side of the turntable and when it comes in contact with the limit switch that will be right next to the turntable, it should notify the Arduino.</p>

<p>Any suggestions on which limit switch I should get?</p>

<p>Thanks so much in advance!</p>
 3557: <p>Instead of a limit switch a hall effect sensor with a moving magnet is an optimal soltuntion since it is contact less there will be no frictional side effects on your application.</p>

<p>But there is one more better way to it, try to use an rotary encoder, something like a 400/600 ppr should also be fine for this, doing this way you have more positional data of the turntable, </p>

<p>You can calculate no of turn, arcs etc.</p>

<p>For eg: </p>

<ol>
<li>A 400ppr would give you a resolution of 0.9 degree per pulse, and </li>
<li>600ppr would give you 0.6degree per pulse of accuracy.</li>
</ol>

<p>Although you can go for even higher ppr encoders but you can get these at very low cost. </p>

<p>Pic from: <a href="https://m.ebay.co.uk/itm/400BM-Rotary-Encoder-Module-LPD3806-360-6mm-Shaft-Arduino-Pi-Flux-Workshop-/112607725039?_mwBanner=1" rel="nofollow noreferrer">https://m.ebay.co.uk/itm/400BM-Rotary-Encoder-Module-LPD3806-360-6mm-Shaft-Arduino-Pi-Flux-Workshop-/112607725039?_mwBanner=1</a> </p>

<p>Note: Just an example, price may be different at other webites, haven't checked the price while writing this solution.
<a href="https://i.stack.imgur.com/7BnyH.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7BnyH.jpg" alt="A 400ppr rotary encoder"></a></p>
 6628: <p>A $2 microswitch with a roller would be OK for a million revs or so.</p>

<p><a href="https://i.stack.imgur.com/okIHN.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/okIHN.jpg" alt="enter image description here"></a></p>

<p>You would put a little ramp on the diameter and use it to trigger the switch.</p>

<p>Non-contact magnetic or optical could be better for more cycles or faster operation.</p>
