Wiring a Corner finder and height control

[Ger21]

When cutting profiles (full depth of your material) then put your touchplate on your spoilboard (probably upside-down in your case as you have a lip on the bottom) and zero to the spoilboard. THEN, click in the Z axis DRO and SUBTRACT the thickness of your workpiece material from whatever the DRO is showing. ie. if the DRO shows 30.000mm and your material thickness is 10mm change the Z DRO to value to 20.000mm.

The reason for doing this is that your workpiece may not be exactly the thickness you think it is. For example, I recently bought some 18mm thick plywood from B&Q. It turned out that it actually measured 15.5mm thick. I'd programmed my toolpaths based on the material being 18mm. If i'd probed to the top of the material then I would have ended up cutting 2.5mm into my spoilboard - and the 2mm tabs i'd programmed to prevent the part breaking free wouldn't have worked. Probing to the spoilboard meant that my spoilboard wasn't damaged and the tabs worked. It also means that if your material is slightly thicker then you'll still cut all the way through rather than leaving an onion-skin.

THIS is what the Material Offset was designed to be used for.

Just set the Material Offset to 18, and zero to the spoilboard, and your Z zero will be set 18mm above the spoilboard. No need to be changing DRO values. The screenset can handle this automatically.

I use a similar method for surfacing my spoilboard too. I have a toolpath created to surface my spoilboard which has a cutting depth of zero. To use the file, i'll probe to my spoilboard as above, then click the Z-DRO and ADD the amount that I wish to take off the spoilboard. ie, if my Z DRO is showing 30.000mm then i'll change it to 30.200mm. This will take 0.2mm off the spoilboard and means I can have one 'surfacing' gcode file which can be changed on-the-fly to remove as much or little material as I want.

You can use the Material Offset with a negative value to do this.