Pressing "Home" Causes Z Axis To Crash

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msadesignworks
Messages : 2
Enregistré le : 05 févr. 2023 03:42

Pressing "Home" Causes Z Axis To Crash

Message par msadesignworks »

Hello everyone, I am very new to CNC and I have purchased a 1.5 Makerfr second hand off of Craigslist.
It took me awhile but I was able to finally flash my GRBL and TFT boards, get the UI to display on the screen, get the touchscreen calibrated via the SD card, and play with moving my axis' using the nunchuck and the touch screen functions to test the motors. (The nunchuck actually stutters quite a bit, maybe someone can tell me what is going there?)
I have not tested anything yet in regards to running any G-Code Programs, I still want to work out a few more kinks before then.

One of those that concerns me the most is that when I press the "Home" button on the touchscreen and the X and Y axis appear to move into the correct position (bottom right hand corner of my table) however the Z axis raises so far that it begins to crash up higher than it is supposed to and I have to press the emergency stop to prevent it from seamingly breaking itself.
I understand the mpos units are my "Home" coordinates, where in the UI or arduino code section am I able to edit those units? Why is my Z going past it's own physical parameters?
Again, I am a complete novice to CNC machines such as this and any and all help would be appreciated.

Thanks,
-Matthew
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HTheatre
Messages : 5912
Enregistré le : 31 mars 2019 08:21
Localisation : Rivesaltes

Re: Pressing "Home" Causes Z Axis To Crash

Message par HTheatre »

Hi Matthew,

When you perform a homing, the Z axis goes up, touches the Z-endstop and goes back from 2 mm, then the X and Y axes move simultaneously, the X axis touches the X-endstop and goes back from 2 mm whereas the Y axis touches the Y-endstop and goes back from 2 mm.

Because the spindle can be anywhere above the work surface when you perform a homing (e.g., closer to the Y-axis endstop than to the X- and Z-axis endstops), sometimes the Y-axis will touch the corresponding endstop first. That's why Grbl scans which endstops are activated and in which order during the process.

So first, check you don't invert connections of two endstops lines on the Grbl board (e.g. Z-endstop at the place of X-endstop). If each endstop line is connected to its corresponding input on the Grbl board, then check the continuity of each endstop line with a multimeter in "current continuity tester" or "ohmmeter" mode. When you do not manually activate the corresponding endstop, the multimeter must bip or display a high resistance. When you manually activate the endstop, the multimeter must stop bipping or display a null resistance.

See ya,
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