Will the PEX crimper come with gauge
Yes
Do I need to calibrate the crimper before every time crimp?
No, the crimper is factory-adjusted, you can directly use it upon arrival. If the crimping result fail to pass the Go/No-go gauge, you will need reduce or add the numeric on the adjustments.
How should I calibrate the crimper?
Add one numeric only in each calibration, i.e. change the default setting with numeric "1" and "2" to numeric "2" and "2". Tighten the locking nut and crimp again, if crimping result fail to pass the Go/No-go gauge again, calibrate it again.