How To Use Inductive Proximity Sensors

[GBWM]

A short video showing how to wire up inductive proximity sensors in our homemade machines. These sensors are used to detect metal. Proximity sensors are useful for example as limit switches in CNC controlled machines like CNC routers, mills, or lathes but the use of them is really wide.

[tonyfoale]

I use those sensors on my lathe conversion.
Here is a photo showing the X-axis sensor in place

Click for full size.

Here is the setup with the trigger bar in place, the gold coloured piece.



For both X and Z axis I use one sensor on each axis with two triggers. Sometimes two sensors are used with one trigger. It depends what you want to do with the information. In my case I just wanted limit switches.

[DIYer]

Thanks GBWM! We've added your Proximity Sensor Wiring to our Wiring category,
as well as to your builder page: GBWM's Homemade Tools. Your receipt:

Proximity Sensor Wiring by GBWM

tags: CNC

[DIYer]

Thanks tonyfoale! We've added your XZ Limit Switch Setup to our Lathe Accessories category,
as well as to your builder page: tonyfoale's Homemade Tools. Your receipt:

XZ Limit Switch Setup by tonyfoale

tags: lathe

[GBWM]

Do you use them as home switches too? I'm wondering how accurate are these actually as I'm thinking of using them in my next machine as home switches.

[tonyfoale]

Do you use them as home switches too? I'm wondering how accurate are these actually as I'm thinking of using them in my next machine as home switches.

I do not have nor need homing switches on this lathe. So the answer is NO. See Ball screw and electronic lathe conversion
If I were to need homing switches on which to base repeatable positioning I do not think that I would trust these proximity sensors to provide the required accuracy. For homing I would choose optical sensors, I used the proximity sensors mainly because I had a few left over from a project of nearly 40 years ago. They do have the bonus of being fairly rugged and tolerant of cooling fluids etc. Optical sensors need protection from the fluids. Hall effect sensors offer better protection but I would not trust their precision as much as optical like these, which are cheap as chips.

[Tonyg]

Do you use them as home switches too? I'm wondering how accurate are these actually as I'm thinking of using them in my next machine as home switches.

I use them as homing switches on some of the large CNC plasma machines that I manufacture and they are extremely accurate. (bearing in mind that you get a wide range of proximity switches which vary in quality and of course price)

[Guy Marsden]

There are also magnetic sensors that look almost identical and they will detect either a N or S pole from a short distance just like these inductive sensors. They come stock with the inexpensive tachometers that I've installed on all my equipment:

[tonyfoale]

I use them as homing switches on some of the large CNC plasma machines that I manufacture and they are extremely accurate. (bearing in mind that you get a wide range of proximity switches which vary in quality and of course price)

Can you put some measured numbers to "extremely accurate"?

[tonyfoale]

Here is a link to sensors in general.
Sensor link