Trick for triple checking xy zero

I certainly am not the only one with a trick like this: I have had issues with losing my zero between tool paths. Its mostly human error, but sometimes machine or computer issue. Sometimes I dont notice until it is too late. I have started to put in a toolpath to mark a spot outside the project area.

Ex: this job uses 3 bits. I include the “spot marking” at the start of each file. So the first thing the machine does is hit that spot. If it does that and you know for certain you are still aligned correctly. Only adds a second to your job. AND say you lose your xy zero, you could always center off that spot. I know these spot for each tool is x = 5 and the y’s are 4.5, 5, and 5.5.

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Hey Greg,

I do this pretty much with every project. It’s a known technique used in machines making electronics. The boards all have 3 feducials and the machine triangulates it’s offsets by scanning these spots on the sides of the boards. I like to use 2 of them on the same axis so I can find my zero and see if the stock is still alligned. I also use it to zero my laser into a carve.
I don’t always dimple on the stock. A dimple on a clamp or a side bar works too.

It is an awesome method to regain any and all zero after an oopsie every time.
Didn’t think of including dimpeling in the actual toolpaths thoug.

Smart thinking!

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So, you add gcode to the beginning of each toolpath which jogs over from 0,0 to a fixed point (which won’t ever be cut) on the workpiece? If so, would you share your gcode ?

I have an XY laser diode attached to the router mounting plate.
It is at a fixed offset from the center of the router. I center the laser cross-hairs on the lower left corner of the workpiece. I then zero the x,y. I run a macro to jog the router to the offset point. Then I re-zero the x,y. It works pretty well. There is a bit of guess-work on how to position the cross-hairs on the corner.
I think I will replace the cross-hair laser with a fine spot laser, and center on a dimple just inside the LL corner of the workpiece.
That should make the alignment more accurate.
I just need to remember not to cut off the dimple.