Neither is better - I use both on occasions. There is some advantage to probing from the spoilboard if you need to do a tool change as you may have machined away the workpiece surface. Of course you can only probe Z from the spoilboard - X and Y still have to be from the workpiece. Alex.
Both have their usefulness. I use machine bed quite often simply because material is very often not an exact thickness.Setting off the machine bed will ensure it's cut right through a board that may not be uniformly sized all over, or perhaps it's actually thicker (or thinner) than the manufacturers stated dimension. However, if I'm pocketing something that needs an exact depth then I would need to probe the top of the work - sometimes probing twice on the same job! Probing from the bed ensures you will not "machete" the tool into the spoil-board.should you miscalculate a toolpath - the spoil-board will not "spoil" so much either. All in all, both methods are needed depending on the job.
Same way as if you were probing the top of the workpiece. In fact if I want to probe Z off the spoilboard I do a full XYZ probe off the top of the workpiece, jog clear of the workpiece and then probe and re-set Z. I don't know what probe/control software you are using, but I have separate macros for probing XYZ and Z only (because I need a different offset for probing Z only). Alex.
How would you use the XYZ Probe Plus to probe Z off machine bed? Seems like you could just flip it upside down but the 4 pin connector is angled slightly causing it to not sit flush.
Mine must be a different version. With the 4 pin connector unplugged it's almost flush but plugged in there's a fairly large gap. I could possibly file the connector down but even then it's not a guarantee.
I noticed when I flipped mine that the connector was not flush either. It was a hair proud of the probe. I just ran the extension connector on the disk sander for a second and now it works just fine. It would sit flat if I applied pressure, but i chose to sand a hair off anyway.
