Homing boundaries

I have a 4x8 stock avid machine. The left side of the machine (the x axis) has an 8’ rotary. This effectively subtracts 16” + a safety margin from the x axis.

It seems it is a waste of time in this use case to home the machine to the left of the rotary. Also possibly unsafe given some rogue gcode or inattentive operator lowering the bit into the rotary equipment.

It seems it would be simple to setup to home boundaries for the machine using the boundaries limits in the configuration screen. mach 4. One would also then adjust along the rail the aluminum blocks.

One could also set up similar home field for rotary operations.

Has anybody done this? It seems there are no downside except for the minute or 2 it would take to adjust the physical blocks and change the limits in Mach 4.

The only issue that may arise is when configuring mach 4 initially, it asks for the size of the table. Are these numbers then hard coded somewhere or they just starting points to fill out the initial configuration table?

One other idea, it seems it would be easy to turn the table into a 4x7 table by sliding the rotary tail to the chuck and adding additii9onal spoil board to level the right of the table with the top of the rotary riails. Has anybody done this?

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I guess you could move the X-- block over and reduce your table width in the config by those ~16", then setup custom soft limits for X. How-to is in the Avid CNC Mach4 Users Manual. You now have a PRO3296! When it comes time to do rotary work, home it as usual then disable soft limits and enable Axes Limits Override so it ignores the sensors. I haven’t done this myself and I don’t know if working in negative machine coordinates will affect any of the Avid rotary alignment/calibration scripts. Also there’s the issue of running the machine with two of the three safeties disabled…

Since I’m thinking about it, maybe a safer approach is to leave the hardware alone and set a custom X softmin at, say, 16". I’m not certain but perhaps you’ll still be able to home left of the soft limits zone then jog to the right to enter ‘the box’ and run gcode. To run rotary, disable soft limits - at least you’ll still have the limit switches active (and the bumpers as last resort).

It is pretty easy to set up two different Mach4 Profiles. One for “Standard Ops” that prevents travel to the rotary equipment and one for “Rotary Ops” which focuses on the needs of the rotary.

I have a 6060 with the rotary mounted along one edge (the south edge). It also has ATC, with the tool holders located along the west edge. ( I’ll stick with that description because I’ve swapped my x and y axis, so it can get really confusing). I added 2 proxs to prevent the spindle from intruding into these areas. I also added a virtual output that can be turned off/on through code or button in mach4. I use the signals library to monitor the proxs and the virtual output. If the output is active AND a prox is triggered the machine estops with a message (Pre-Limit triggered). For tool changes, the virtual output is deactivated. This prevents the AND condition so the prox is ignored. After tool change the virtual output is reactivated.
The same thing applies to rotary jobs; deactivate the virtual output to cross the prox. Once reactivated, the prox acts just like a limit switch.
Finally, the actual limits are placed in the normal locations for a 6060 table, as well as the soft limits. All homing is done with the original limit/home switches.