About homing and switches...

[JAZZCNC]

Paulus.v Explanation of Homing on an index is spot on, however, I think you'll find that most Closed-loop Hybrid servo encoders don't provide an index Pulse so can't use that feature.

Regards Homing and Zeroing etc then you need to get into the habit of thinking in terms of Machine coordinates and Work coordinates. Home switches define the Absolute ZERO machine coordinate position. This positon NEVER changes and is used to reference WORK coordinate ZERO.
So when you send the machine to HOME your sending it Machine ZERO. From this position, you can also define machine limits.

WORK zero can be anywhere inside the work envelope of the machine. You'll often see reference to WORK offsets, these are just areas inside of the machine work area which can have separate WORK zero positions.
This means you can assign each area to a Fixture G-code ie: G54 G55 G56 etc and use these codes in your cutting G-code file so it moves to the next fixture and starts cutting from new Zero point.
This is useful for instance when have several different parts or materials setups on the bed. For instance could have G54 reference to point on the Bed while G55 references to corner of a Vice and so on.
Each would have there own Zero WORK coordinate and all are referenced from the MACHINE Zero.(HOME). From MACHINE ZERO any location inside any Fixture Offset can be located accurately.

[routercnc]

Picking up on question E) in post one - you could use a Hall effect sensor but they need a magnet 🧲 on the moving part and are likely to attract steel chips and filings and become unreliable. Proximity sensors detect steel or aluminium so are a better option. Your other options include cheap small micro switches or chunky industrial ones.
Ideally have the detected object on the axis run past parallel to the face not up to it so a fault means the axis crashes into the hard end stop not the sensor.
Oh and welcome back Jazz 🍻!

[JW1977]

Thanks!

Proximity sensors seem like the option i will choose.
Is there anything special i need to now about using them?
As i understand i will use 6 of them and one of each axis will double as home switch right?

[Robin Hewitt]

If you are cutting steel do not use one requiring a magnet.

The detector detects a passing object so it cannot be crushed if it fails.

[routercnc]

In terms of proximity sensors :
I would go for the 4mm distance sensing type

Prox sensors are more sensitive on steel targets compared to aluminium

They run on something like 12V -30V, typically 24V. When triggered they output this same level so they can’t go straight into a 5V BoB ( is my experience) without doing something to the signal. If your BoB can take this higher voltage then no problem.

[cropwell]

Have a look at this thread

http://www.mycncuk.com/threads/10262...oes-nt-it-work


You can regard the LJ12A3-4-Z/BX as a normally open relay, where the output is switched to GND when activated. The fact that you supply 12-36V to the electronics of the induction sensor is a red herring. The unswitched output virtually floats and usually pull-up resistors in the BOB strap it to 5v. Meter your BOB input and you should find 5v. If you don't, then you have either buggered the BOB with mis-wiring or the BOB needs a 5v external pull-up resistor. I'll just clarify that last phrase - a resistor to pull the BOB input to 5v, I use a 10K if necessary.

[paulus.v]

Thanks!

Proximity sensors seem like the option i will choose.
Is there anything special i need to now about using them?

You have mentioned that you will be using the CSMIO IP-M controller. This controller is using the industry standard 24V inputs and you can use either PNP or NPN sensors, the 10-30V type.

As i understand i will use 6 of them and one of each axis will double as home switch right?

If you put the sensor on the moving part and have two metal triggers on each end of the axis you will actually need only 3 sensors, one for each axis. And yes, the sensors can be used as both home and limits.
For security reasons it is advisable to also have limit switches that will cut power to the machine before reaching the end of axis travel.

[JW1977]

You have mentioned that you will be using the CSMIO IP-M controller. This controller is using the industry standard 24V inputs and you can use either PNP or NPN sensors, the 10-30V type.



If you put the sensor on the moving part and have two metal triggers on each end of the axis you will actually need only 3 sensors, one for each axis. And yes, the sensors can be used as both home and limits.
For security reasons it is advisable to also have limit switches that will cut power to the machine before reaching the end of axis travel.

Yes, i got the IP-M controller.
Are you saying that i can use one sensor /axis that doubles as limit switch and homing switch or do i need one homing sensor + one limit switch /axis?
Btw im using a driver by the name 2HSS86H.

[Neale]

Yes, i got the IP-M controller.
Are you saying that i can use one sensor /axis that doubles as limit switch and homing switch or do i need one homing sensor + one limit switch /axis?
Btw im using a driver by the name 2HSS86H.

You can use one sensor on the moving part and two targets, one at each end. In normal operation, this acts as the limit switch but during homing, Mach3 and the IP-M know that it is being used for homing and it does not act as a limit switch. As soon as the homing operation is complete, the switch becomes a limit switch again.

I use Mach3 and IP-M. I use a proximity switch at each end (so two swtiches on X, two on Y, and one on Z as it is difficult to use a limit switch for the bottom of Z travel). It is easy to wire the switches on one axis in series so that upper and lower limit switches are connected to one IP-M input. This means that you can home X and Y at the same time. My machine is configured to home Z first (to get the spindle to the highest point to clear anything on the machine), then X and Y together. This saves a little bit of time on a bigger machine and works well.

If you just use one sensor per axis with a target at each end, then you can still wire each sensor to a separate IP-M input channel, obviously, and get the advantage of homing two axes at the same time.

I had one small problem with my Z axis homing. As I said, my machine first homes Z, then the other two axes. However, these proximity switches sometimes have their on and off trigger points very close together. What this meant was that when my Z axis was homed, the switch was so close to the target that a tiny amount of vibration could cause the switch to trigger accidentally and this often happened while X and Y were moving. The answer is to configure Mach3 so that the home position is very slightly offset from the actual switching position - I use about 1mm. This avoids accidental triggering.

[JW1977]

Ok i see, thanks... It would be interesting to see how you put the switch on Z, do you have any pics that you would like to share?
To use one sensor and two targets... Arent the sensor pointing towards one of them, how can you make it work in two directions?
Would you recommend using one or two per axis? Obviously you choose two, but why?