I watched this video on inlays, , and with the cnc setup he uses two touchplates, one when he starts a new workpiece which is a rectangular metal plate. There’s another round one that’s embedded in the spoilboard that he uses when changing bits but staying with the same workpiece. Can anyone explain how something like this works? Does his controller track a machine zero and a work zero, and each touchplate affects one or the other? Is that possible with grbl and the opencontrol software? Or is it all simpler than I think and he’s just manually doing something off camera? I’m new to cnc, but I can see where something like this would be really useful if you need to switch bits after a workpiece no longer has any flat portion left to balance a plate on.
I'm not sure if he's doing this (sorry didn't watch the whole video - bedtime here) but one thing you can do is use the spoil board as your reference for Z zero. You set your origin in cam at the bottom of the workpiece. Your workpiece has to be accurately thicknessed for this to work, but it does make resetting Z zero after a toolchange easier. Alex.
The one that is embedded is a tool length measurement one used after a tool change. Basically, when you change tools, it touches off on that permanent one and the z height is adjusted for the new tool length. I was going to do this, but to me it is just as easy to just use my normal touch plate on the work surface after a tool change. However, when doing carves where much of the surface has been removed that would not be feasible. That is why there is the second permanent known one. At about 26:40 its use is demonstrated when he changes to the v bit. The machine only touches off on the permanent one. I am not sure if OpenBuilds CAM can do this, but I use Estlcam and it gives me the option to add a permanent one at a known location on my machine.
New to carving but it seems that keeping a scrap piece of the original stock as a zero reference would be simple enough if you can remember to do it.
But then you would have to have one for every thickness of stock you have. Much easier to use the tool length measurement touch plate.
