two independent heads on one Y axis

I have a gantry with two tool heads, they were originally meant to work in tandem on production runs.

I would like to use one head for the drill and the other for the laser.

The drill works fine on the y axis.

The laser works fine when mounted on the drill. But the 25 kg drill has a bit of inertia and enhibits the laser to move fast for engraving.

Each head can be parked out of the way so they would not be traveling together.

My question: my question is how to select a head (tool) to park the drill and make activate the laser.
and vice versa?

Also, it would be nice if the Y coordinates be used for both heads.... in other words, I wouldn't have to post process the Gcode for to change the Y axis to A . but this is a possibility.

There is more than one way of doing that, but the easiest would be to make separate configs and start the one you need, it works very nicely but you can not use both tools at the same time.
You can make a config with xyz and a or u or v or whatever as the second x or z, you can use both at the same time but requires a bit of gcode editing or filtering.

It this senario you can do this with the drive enable signal.

If using laser, enable laser y axis motor drive.
If using drill, enable drill y axis motor drive.
In this config you can enable bot'h drives with only Gcode for Y0 with fixed tool offset.

If you want to use them bot'h in the same program for different operations.
You have to use Y0 (laser) and Y1 (drill) in your axis config and use tool offsets.

Good luck, and the machine looks stable !

this machine was built like a bridge.

I like the motor enable solution. Just one pin controls one motor or the other. I will keep posting progress.

I am currently building the laser head - 7W Nichia with integrated PWM drive in the copper holder mounted on 2kg copper block with a copper heat sink and a 15W blower which is temperature sensitive (the hotter the air the more the blower works) all that mounted on a 8mm thick aluminium U channel which also provides heat sink.

After checking the motor enable, I found it was difficult to use without getting lost in the coordinates.... homing at two different switches makes it confusing.

Since I have 4 motors, I have 4 axes.
kinematics are trivial
The V is supposed to be parallel to Y

[TRAJ]
AXES = 4
COORDINATES = X Y Z V

You might want to think about which tool needs to move fastest as the controller does much better blending and lookahead in XYZ than with other axes.
But then you can't do XV arcs at all....