"Z" ccordinate too deep for lettering

Trying to find out if I have a procedural problem. New to CNC. Got my XXL a month ago. Designed a sign where I cut out the waste around a 6" letter using a #201 EM. Then, position the lettering to v-carve out a name into the letter. Everything looks good in the simulation. I enable/disable the tool path files to save 2 g-code files, one for the .25EM bit work, and one for the V-bit cutting of the letters. I use the probe for X, Y and Z coordinates in bottom left corner, then load and run the .25EM waste removal. Everything looks great. Then, I install the v-carve bit, and re-probe just for the new Z bit height. After the probe for Z, I do not zero anything, thinking that the probe should set it like it does when I started. When I load and run the toolpath for V-carving, the bits are cutting too deep into the board, causing the letters to be deeper and wider than required.

I experienced a similar problem with a change to a ball end bit earlier today, using the same procedure. The router over plunged into the board for an edge profile I was testing, ruining the project.

Was the probe hanging over the corner of your stock when you probed for Z only?

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Put this another way, for Z ONLY (zeroing for changed bit) using the probe you put the block totally on top of the stock. Do not hang lip over the corner or edge.

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After this issue is mentioned so many times, I feel that Carbide should have little cards like those that come with the items we purchase where the instructions for how to use the probe with a little diagram are printed. Since it appears that most people don’t download or retain the operating info. Such a small card could be kept with the probe next to the Shapeoko to remind people how to use it correctly including a reminder to test the probe by touching the endmill to see if the red light turns on before pressing on Probe in CM.

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Thanks to all for your input. Having worked in IT for 30+ years, I now find myself the victim of the same advice that I’ve given out so many times. “RTFM”. (Read the <insert favorite “f” word> manual). Seems that of all the materials I printed, that one eluded me, and I guess I relied on some You-Tube video I saw in all my research prior to purchasing my Shapeoko. I don’t recall if there was anything in the probe packaging directing me to the documentation, not that I’ll take that as an excuse. I’ll be back in the shop in about an hour to retest. Fortunately, I have about a zillion board feet of scrap lumber from various projects that are just waiting to be cut and carved into fireplace kindling.


Just a final note. I tested a few cutouts, using the probe as suggested. Worked like a charm. Thanks again for all the feedback.


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