My homing cycle only checks the upper z axis, the left y axis and the right x axis, is this normal?
It will only home to one switch on each axis. So that aspect of what you’re describing is normal. Whether or not the correct switch is being activated on each axis is dependent on your specific system.
If those are where the homing switches are, then it’s golden.
The switches tell the controller where the zero position for the laser head is on each axis, after which the controller knows where it moves the head.
Conversely, if you shove the head around by hand after homing, the head is not where the controller expects it to be, after which Bad Things™ happen.
Thanx, Any clue how I would determine that?
Everyone is calling these homing switches, am I correct that these are the same as my hard stop switches?
Is this a custom build? If so, how did you design your machine? If it’s not, what machine is this?
The most “straightforward” would be for your machine to home to the front-left and for origin to be similarly located at front-left.
A Home switch determines the zero coordinate during startup.
A Limit switch catches out-of-bounds motion that may be due to the motors losing steps, head crashes, manual intervention, or whatever. A machine may have a limit switch at each end of the axis travel or may use the home switch as one of the limit switches.
You can configure GRBL to home during startup (with control over the direction & speed & switch polarity), then activate either Soft or Hard limits. Soft limits calculate the endpoint of each move and will not go beyond the limits set by the (known) size of the workspace. Hard limits depend on having two limit switches to catch the errors.
The GRBL doc has far more detail on how all that works:
Your profile says Neje 30 W, so each axis likely has a single switch used as the Home switch. Some desktop lasers have no home switches at all, which inevitably leads to confusion when the homing cycle gets (inadvertently) activated. No desktop lasers I’ve heard of sport hard limit switches, because those would increase the hardware cost and ain’t nobody gonna pay for that.
I have stopped homing.
I manually position pre a job.
If it fails for whatever reason, too bad, start again.
I zero to the starting position.
The hard limit switches are in place to save from disaster.
To implement limit switches, it requires a switch on both ends of both (or all) axes.
Most of the grbl machines use the home switches for limit switches after the home function completes… however this only protects against over travel in those two directions, not the required four.
The Ruida ignores the home switches after it completes the home function. It usually has limit switches outside of the defined work area, meaning you loose real estate with limit switches.
On the Ruida, it requires 6 switches generally, two home and 4 limit for 2 dimensions. Another axes, two more switches…
If you used the home switches as limits it might work… it also might fail to boot properly, at least with the Ruida…
The number of switches required on bottom dollar machines is probably why they don’t use them… it’s also more things to go wrong. Switch are so costly that many of these machine do not come with home switches… 
The two limit switches only protect one direction of each axes… you’re only other option is to enable hard limits.
Small roller micro switches are relatively cheap. But add in brackets, trip flags, mounting, wiring, engineering, and labor and you get the real reason for not including them. HOWEVER, if you DIY the project, you get Home and Hard Limit capability dirt cheap. Not saying you have to have any of it, but I could not resist! 
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You can add all that on pretty cheap, as you say… I say I’d rather spend that money and time on other things that make more of a difference to me…
I think it’s a slim change of an out of bounds running a job. It has happened to me, but I was under the hood trying things… It has not damage anthing on mine and I’ve been sort of brutal with my machine… I’m sure it’s not built to crash…
If the head was one of the $10k types… I might come to a different conclusion about using limit switches…
If you want to do it… do so… and don’t forget to have fun… 
I just finished up my “Portable CNC/Laser” setup. Ready to play (have fun) with it!
I’ve got 2 proximity switches on the Y axis and 2 micro switches on the X axis hard limits, all not cheap. They are in series to hold up a relay which cuts motor and laser power.
Nothing clever, I have to stop the job being sent manually, but I reckon if it has gone badly wrong the job is stuffed anyway.
This setup can be easily added to any machine, relays on the 12V, 24V or 240VAC and leave the controller powered up.
If the machine does go out of bounds, then you should think about dropping power to the whole unit.
If this failure was your controller, it might decide to burn itself up… That’s why a good emergency switch dumps the power to the whole machine. If you don’t do that, you guessing as to what’s going to fail. There is no advantage to keeping the controller powered up, it can’t recover…
Just my view…
I agree 100% on this point. Kill the motor power and you will be starting over. (I know I am repeating Jack’s words, but I think it is worth repeating.) Relay failures DO happen, especially with imported types. Imagine that laser relay not dropping out. My E-Stop kills the power to the controller board. I mean it is an EMERGENCY, right?
In my decades of computers I have replaced more mechanical relays that I though ever existed… I have never been required to replace a ssr type device.
I just don’t use mechanical relays… They have lots of bad tendencies, such as induced emf in adjoining circuits and inverse voltage from a collapsing field… the main disadvantage is simply they are mechanical and mechanical stuff eventually fails.
You can handle most of these issues with external components and layout, but in the end, it’s mechanical and the weakest link in the chain…
There’s little difference in cost, compared to ssr. For ac ssr switch at the zero voltage, making it much easier on the equipment.
I haven’t found anything positive about mechanical relays and have been off my use list for a couple decades or more… I wonder way they are still used in these applications…
You can’t switch a generic 30A mechanical relay with only 20mA like a ssr can.
Just another view point…
True, but I was reluctant to risk it with an SSR on the Arduino A3 pin. Also, I have a stock of the 12v coil, 5v trigger relay boards and SSR’s are definately not cheap. I concede I would never use these relay boards, or anything else China, in a production machine.
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