Z axes goes up when starting send the gcode

after i finished my projects,I want to start new one ,the z axes goes up and hit the limit switch and damage it,
i want to know if the limit switch is normally close or open , because now when i start sending the Gcode ,the z goes up ,to the end ,

@JamalAlabbood Can you post your gcode?

There is a lot going on there and it really depends on how you have your machine configured.

First, limit vs homing.

Most people use the switches as homeing switches only - which means that GRBL is only paying attention to the switch inputs when you run a homing command ($H - Run homing cycle)

I run them only as homing switches because random RF noise would cause a false switch trigger signals and shut down the carve.

You can set up Soft Limits ($20 - Soft limits, Boolean) - which is the machine will shut down rather than move past the max axis length ($130, $131, $132 – [X,Y,Z] Max travel, mm) but for that to work properly you must home your machine first.

Z Height. If you are setting your Z height using G92, it is a temporary offset not stored in the EEPROM and will be cleared out at the end of each cycle. So you will need to reset it before each carve.

Z Clearance. This is the height the bit will be raised to before it begins moving. You should check in whichever software you are using to generate your gCode and make sure that it is at a reasonable value.

If you could post what software setup your are using and your GRBL Settings ($$ - View Grbl settings) that would be helpful.

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thanks AaronMatthews for your replay , I found the z in setup material is 1.80" because I work with ready made projects and I set every thing
only this ,I set it to 0.8" and works good
thanks alot

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