[kolias]

Making a new table top cnc and would like to use these NPN I got a few years back (10 of them). In the past I have always used mechanical type limit switches but now I would like to learn how to wire them NPN and how to use/install.

The attached picture is what is market on the body of each NPN and of course I don’t understand anything. There is a box in the middle line which I assume represent a resistor or diode? What type/size?

I do have a 12VDC power supply and I will try to wire one after I get a feed back from you just to experiment with it

Also in my X & Z axis I have 2 limits for each axis which I normally combine all of them but with the NPN how do I combine 4 of them?

Thanks

[Vlod]

The box is a pullup resistor.
You need it to keep output high.
Usually it is 10k resistor.
You can use diodes to tigh all outputs you want to combine , they would act as check valves, to one input on the board.
I use proximity sensors on my machine and they work good.

[kolias]

The box is a pullup resistor.
You need it to keep output high.
Usually it is 10k resistor.
You can use diodes to tigh all outputs you want to combine , they would act as check valves, to one input on the board.
I use proximity sensors on my machine and they work good.

Thanks for your time mate, when you have a chance is it possible to send a picture how you mount the NPN lets say in your Y axis? I just can't see how to mount the NPN which is like a 1/2" bolt about 2.5" long to prevent the gantry going over the limits. Perhaps when I experiment I will find out....

[Vlod]

The plates is about 3mm from the sensors when they come next to it

[Vlod]

Yes, the sensors are big but there is no problem mounting them.
The one on the left is for X axis and the one on the right is for Z axis.
I use them to home all axis.

[kolias]

Yes, the sensors are big but there is no problem mounting them.
The one on the left is for X axis and the one on the right is for Z axis.
I use them to home all axis.

Much appreciated, first time I seen these sensors in action. It is true that they are big and not as convenient to locate as the small mechanical ones shown in the attached picture from one of my previous machines. Now I will work to find out the best way to mount them.

[Vlod]

One of the options …

[kolias]

One of the options …

Excellent idea, thanks, I was thinking the same but instead to make a bracket to hold the NPN vertically pointing down on the plate.

BTW when you say your sensor is 3mm from the plate what happens when the 3mm increase/decrease? Would this make the axis stop closer/farther?

[Vlod]

It actually slides over the sensor, you should check at what distance it triggers reliably before mounting.

[kolias]

It actually slides over the sensor, you should check at what distance it triggers reliably before mounting.

Each sensors has 3 conductors, what kind cable are you using to connect them to your control card? I don't know of any cable with 3 conductors. Does it have to be shielded cable?

I can see problems fitting them on the Z axis where space is limited. When you have a chance could you sent me a picture of your Z axis setup?

Thanks
Nicolas

[Vlod]

I’ve used control cable from Homedepot. It is multi stranded and shielded. They have two, three and 4 conductors …
The first photo I’ve sent actually shows Z axis on the right.

[Vlod]

Send a photo of your Z axis, maybe somebody has an idea….

[kolias]

Many thanks for the info, I now understand the cables. My current machine is under construction and have no pictures yet however I attach 2 pictures from one of my previous machines which is kind of typical. You can clearly see the Z axis with the 2 red mechanical limits and also the X axis, pretty busy area to fit the new sensors which are quite long. I will give it a try though and if I can't fit them I will use again my mechanical friends.

[Vlod]

I would install them this way

[kolias]

It will not work that way. The Z axis moves up/dn and the X axis moved left/right and it may hit the sensor. But at least is one option. I'm about 20% building the new machine and the stage to do the limits is about early to mid summer. Making it in 3/8" thick aluminum is time consuming since every hole has to be tapped and its the only part I dont like!