I have been using the user defined macro capability in Carbide Motion to set a zero location that I can store when working on v-carve inlays requiring multiple machining steps for cutting boards. I will determine the exact center of my stock and mark that location with a pencil. I have set up a corner jig on the waste board surface so I can always mount the stock to the same location. After completing one inlay and clearing the plug, I remount the board to machine the second step of the inlay. This happens over multiple days and the machine gets shut off between steps. When I go to the second step, I enable the user defined zero. The issue I’m having is that the machine does not move back to the exact center of my stock as defined the first time. It is close but not exact. I must manually adjust until I can align my bit with the mark on my work piece. It happens every time I shut down the machine. It is alway slightly off when I start back up and the amount by which it is off is random. Does anyone have experience with this and ideas on why this might be happening?
One reason may be that the homing switches will have some level of inaccuracy themselves. Unless they trigger in exactly the same spot, your saved zero will move by the same amount.
If you are comfortable fiddling with some of the settings on the controller, there is a setting that may help. You can change the speed it looks for the homing switches, a slower speed may result in more consistent triggering.
I’m not in front of my machine right now, but GRBL setting $24 sets the homing feed rate.
Here’s a walk-through for changing GRBL settings. Just use $24 instead of the example setting.
I appreciate that information. I do not have BitZero installed on my machine, will that make a difference in the procedure you suggest? Is BitZero a reliable tool to always return to a pre-determined zero location, or will I experience similar issues regardless? Finally, if I decide to fiddle with the settings, is there a way to return to the factory settings?
In this case, you don’t need the bitzero. The link was about how to change a value in GRBL, not that you should do everything in the link, since it is solving a completely different problem.
Since it’s just a single value ($24), just write down the current value before changing it. You can always see what the current value is use the $$ command