I am trying to automate part of my business using OneFinity and Fusion360. At This point I’m doing ok with X and Y axis but the Z is killing me. After zeroing my Z on the spoil board I run the G-code for the design but each time where the Z axis is supposed to cut “TO” the spoil board but not into the spoil board it is cutting into the SB by about 4mm while showing on the display that the Z axis is at the Zero height???
Can someone help me.
Please describe your process for zeroing Z
turn on display, then my One finity controller. Home the machine. mve X&Y to where I want and Zero each individually. Move X&Y where I can lower Z to spoil board and lower Z until the bit touches a piece of paper then Zero the Z.
Hey stradibarrius,
if you probe Z on the spoilboard, then because in your CAD drawing, the zero point is at the lowest point of the part you want to work on. Is this the case?
Hey stradibarrius,
is it this issue persisting?
If yes, if you checked that it is not a crimped wire loosened or slipped out of pin in the Z stepper cable, did you check the mechanical connection between stepper and ball screw, like here:
did you set z zero in fusion to wasteboard or material?
Yes, I read the post about the cable troubles so I used my volt/ohm meter and everything checked ok.
Yes, the bottom of my stock is to be the bottom of my finished product.
Am I correct in thinking that the Z zero is the lowest point that the bit should travel?
Hey stradibarrius,
but have you read that in some cases connection was intermittent at times, like reported here and here, which means errors appear depending on movement/stretching of Z stepper cable - difficult to find when measuring at standstill. This can only be found by constantly measuring while moving/stretching the cable (while it is disconnected from controller and connected to multimeter constantly), and by doing this for all wires of Z stepper cable one by one (or to simplify, for one coil and then for the other i.e. measuring between a+ and a- and then between b+ and b-)
Hey stradibarrius,
If you zero your Z on spoilboard, then it would be good for the spoilboard if the bit did not travel lower 
. But seriously, the correct answer would be no. If in your CAD model the vertical zero point is set on the upper side of the part, then of course bit has to go lower than zero. Otherwise you would mill air.
The vertical zero point in your CAD model and the vertical zero point in the CNC machine have to correspond.
If you want to zero the vertical axis (Z) of the CNC machine on the spoilboard, then in your CAD model the vertical zero point has to be on the most lowest point of your CAD model too. On the other hand, if in your CAD model you have the zero point set on the highest point of the part, then on the CNC machine you got to zero the Z axis there, i.e. on top of the workpiece.
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mathmatically,
0 is the top of the z slider travel
-133 is the bottom.
Z Zero is whatever point your cad is referencing the material thickness of the stock. Typically, when setting up your zero points, there are two options for z. From top of material or top of the wasteboard. When physically zeroing z, using paper or probe, you need to zero from the same spot you picked in your CAD. 99% of the time, it will be from top of the material. These two much match, the digital cad zero and the physical zero. My guess is yours does not.
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Thank you everyone for the great responses. If there is anything else to consider please speak up