[Mr.Chips]

Setting up mechanical switches for XY and Z.
I want all three to be in their home positions when I REF ALL HOME, but how does the CNC know where their home is?

There must be some place that you tell it, and where is that?

Sounds simple, can someone tell me?

Thanks

[RaderSidetrack]

One way is to use "home switches". See section: "4.5 Limit and Home Switches" in this PDF:

https://www.machsupport.com/wp-conte...all_Config.pdf

[CNCMAN172]

You typically put X home on the far left side of the axis. The Y axis is traditional all the way to the front of the machine. The Z axis is traditionally reversed meaning going home on Z is the farthest position above the table. You test each axis and ensure that axis starts moving in the direct of that axis home switch. If it moves in the wrong direction change config in Mach3 to reverse home direction.

[viroy]

I use one of these on both sides of each axis: (so you will need 6 for 3-axis)
https://www.ebay.com/itm/272454184681?

They are inductive proximity sensors that trip when roughly 4mm away from another piece of metal (no physical touch).
with these in place, you can ref-all-home as long as you link each axis pair to a single input, so you will need to use 3x inputs (a pair for each axis).
----------------
If you would rather a touch sensor:
https://www.ebay.com/itm/160884893454?

Work the same way but need physical contact
----------------
For the Z-axis, Height is typically inconsistent depending on tool used... a touchplate will automate the task.
https://www.ebay.com/itm/234282797882?

[joeavaerage]

Hi,

I want all three to be in their home positions when I REF ALL HOME, but how does the CNC know where their home is?

Prior to mach being homed or reference it does not know where the switches are. In fact that's what they are for, when Mach does find them then it knows where the machine
Home is....where the switches are.

You can in fact put the switches anywhere you like. It does not matter whether a home switch is in the center of travel, or whether it at at the end or near to it. All that really matters
is that it stays the same. I have my Home switches about 10mm 'inside' one of the limit switches.

When you set up Mach homing it asks 'which direction should I go to find the home switch', you can answer 'go right' or 'go left'. If you had a home switch in the middle the machine might
'go left' because that what it knows to do, but if the switch is already behind it, then Mach wont find a home switch BEFORE it bangs into a limit switch. That why I have my home switches
very near the end, then if I say 'go left', the switch is almost certainly ahead not behind.

Craig