Cr touch zero offset issue Z axis won't go below zero

I recently installed a silent mainboard 4.2.7 to an Ender 3 replacing a 4.2.2 board, and I’m now trying to add a CR touch sensor. The firmware that I have found is this one, Ender-3_HW4.2.7_SW2.0.8.28_CRTOUCH_standard.bin
After updating and resetting as per instructions I am attempting to set up the zero offset.
Motion, Auto home, Motion, Z Axis and then lower the axis until there is a 0.1mm gap.
The issue is that the axis won’t go below zero and the nozzle is still a couple of millimetres off the bed. The documentation shows that this needs to be a negative number and once the offset is found the figure is input into the offset setting.
Can somebody please help?

Hi @Duke2k and welcome to the forums.

There are several things you really need to check when setting up the printer, rather than run the risk of missing something I would recommend checking out a video such as the following as you may find some tips or tricks that will assist you in your process…

CR Touch Install Guide – Complete Walkthrough!

Thank you. I watched that before I installed it but where he lowers the z axis to a negative number, mine won’t go below zero. I think it’s a firmware issue but I can’t find anything else.

If you are unable to specify a negative value then check you are adjusting the correct value. The Z movement value should 0 when performing the bed leveling, it is the z offset that requires adjustment and should allow a negative value.

The Z axis motion value will only ever allow a value no lower than 0, its the z offset that allows the negative values.

Ok thanks. Do I therefore lower to zero on the z axis then lower further using the offset?
The instructions and online tutorials show finding the negative using z axis and inputting that value into the offset.

Yep usually you would go into the motion menu and set the z to 0, then you would go into the other menu which allows for z offset adjustment and use that to set the nozzle height from the bed :slight_smile:

So I did as suggested and it seemed to work but the printer then gave a heating failure message as the nozzle gets to 195 then drops back to 189 and then goes up and down.
All of the wiring is tight and the thermistor is in place.
If I revert to the non cr touch firmware the heater works perfectly.
I really don’t understand what’s going on with it.

It sounds like you may either not have the voltage selection switch on the printer in the correct position or you may need to PID tune the nozzle and bed so that the firmware is aware of how long it takes to heat everything up and also how to keep the temps stable.

It only happens with that firmware which is for the ender 3. If it were a printer issue then surely it would be happening with non cr touch firmware?
It works perfectly without the Cr touch installed.

Different firmwares work in different ways on different printers. Plus there is 2 variants of the Ender 3 mainboards so you have to be sure you are using the correct firmware for the chip installed on your particular board.

I recently installed the 4 2.7 board and used Ender-3_HW4.2.7_SW2.0.8.28_CRTOUCH_standard.bin

Since removing the cf touch the temperature has operated properly and so has the printer.

The old board was the 4.2.2.

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