Home/Limit advice, please

Are these switches you have NO ie (normally open contacts) and are they the sensor type.

For a small mill just 3 would be ok one at the top of Z (Z should be -ve going down) and one each for X and Y they can be setup as a home switch including soft limits.

Now you have your mill working it is better to edit the HAL and INI files by hand. Or make a new config with the switches in, then copy and paste the relevant bit sto each of the two files.

Clive,

Well, I don't have switches at the moment - I'd have to source those.

But...I would think that Normally Open would be what you'd want for individual switches, but if wired serially, as bbsr_5a was suggesting, then surely I'd want Normally Closed?

- Bob

Normally closed is usually suggested since a broken wire
will result in a fault and stop

For a Taig mill you probably can just push it to the hard stops when turned off, then home it when you start up (in no-move homing mode)

More (potentially) dumb questions - sorry!

Pushing to hard stops sounds good, and that lines up with advice I've been able to dig up, over in the wiki.

But...This is a Taig, and the hard stop for (say...) X is on the right end of the table, along with its stepper.

This leaves things feeling backwards, as my HOME position value should probably be 11.7", vs 0.0", when up against the hard stop on the right.

Seems like I should probably reverse the axis coordinates, so that the hard stop on the right becomes 0.0". Am I misunderstanding this?

And if not, there's the matter of how to do that so that the physical axis and its GUI and DRO representations are consistent. Suggestions?

Thanks!

- Bob

It's simpler if the home / stops are at or around zero, but that just means that you configure so that _machine_ coordinates of that axis are negative.
Nearly every Z axis is configured with zero at the top of travel.
You don't work in machine coordinates so don't even notice.

Do _not_ reverse an axis. That will mean that G-code males mirrored parts.

So, it is quite normal to see home 0, max 0 min -127mm