Fast HOME then slow HOME

[mael]

This community helped me out when I was really new to CNC12 and ACORN and I'm still learning.
This is my way of helping back (for what its worth) and hopefully you guys can work on it too and improve and/or correct any mistakes I made.

My Home sequence starts with Z, X and then Y respectively using only 1 input terminal with the switches wired as normally closed to all the axis.
I did a few modifications to the HOM file where it does the following:

-Does a FAST move towards the home switch and hits it
-Backs off a bit
-Does another home at a SLOW feed rate then hits the switch again
-Backs off at a certain distance (offset from home switch)
-Set machine zero

It does the same this on the X and Y axis.

I've placed comments so you better understand and modify to your specifications.
Make sure to make a backup copy of the HOM file elsewhere in your PC.

cncm.txt

(1.18 KiB) Downloaded 171 times

I made a video explaining and demonstrating how it went.
https://www.youtube.com/watch?v=KF4lpVtvMXk

credits to Scott and Marty.
Scoty made public his z probe files which made me digest of how to code and marty's video https://www.youtube.com/watch?v=l1xUtRwN6T0 to help me understand on how to attack the problem.

[Gary Campbell]

I would suggest putting a "G90" line in near the end. Since G90/91 are modal, you do not want to home and set to relative mode

[martyscncgarage]

Might I suggest using the Park feature of CNC12 before shutting down for the evening. What it does is rapidly move your axis to near machine home. That way when you start up the next day, the machine has very little to go to hit the home switches, drastically cutting down on the homing sequence.
Marty

[mael]

As suggested by Gary.
Here is a version 2 of the file.
Thanks for pointing that out.

Change the txt extension to .hom

cncm.txt

(1.15 KiB) Downloaded 205 times

[frijoli]

Very cool. Works just like the probing process.

[Gary Campbell]

mael...
Don't ask how I know.

[Verminator10]

Hi,
Does anyone know how to get this to work on a lathe with encoder feedback on the spindle? G90 and G91 don't work (have different function on Lathe I think) and if I use a G1 command for the movement I need the spindle turning.

Thanks,
Carl

[Centroid_Tech]

That is because the Lathe's default is feed per revolution which requires feedback from the spindle encoder. If you don't wish to have that spindle encoder feedback, issue a G98 before you issue your G1 commands. The G98 places the system in a feed per minute mode.

[Muzzer]

Might I suggest using the Park feature of CNC12 before shutting down for the evening. What it does is rapidly move your axis to near machine home. That way when you start up the next day, the machine has very little to go to hit the home switches, drastically cutting down on the homing sequence.
Marty

Still struggling to understand why it isn't possible to save the current machine coordinates at shut down. Most other controllers seem to manage it, so at the very least it should be something you should try to achieve - unless the machine is unsuitable. Don't see any obvious reason / limitation that prevents it but what would I know.

I'd already figured out the possibility of homing before powerdown myself but only as a half-ass workaround. Running my machine to the far extents in X and Y is a PITA and looks rather toytown.

I'm sure this thought has occurred many times before - what is the issue that prevents it?

Murray

[cnckeith]

Cnc12 saves the wcs positions.
So not sure what you are asking for? Please clarify.

Also you can simply create a macro to park the machine anywhere you like prior to shutdown if you're not satisfied with the built-in Park feature. You can assign that macro to an auxiliary key for convenience or even one of the macro buttons on the wireless MPG.