I had been having z-homing issues with my shapeoko 3 XXL pro for a while. It seemed like it was a connection issue with the z axis sensor, because the sensor would sometimes not light up when the z-axis was near it. I would barely move the cables/connector of the z-axis and it would stop crashing. I replaced the limit switch, had it happen again, then replaced the cable from the limit switch through the drag chain and that seems to have fixed it.
Now when I’m running a program with carbide create, it does fine from initialization through the first tool. Right after the first tool is zeroed and the spindle is turned on, the z-axis is crashing (in the up position). The sensor is lit, and I don’t have any reason to believe the sensor is not working as it should, since it work correctly all throughout initialization.
Question: Shouldn’t the z-axis limit switch be an absolute stop for the axis, even if the g-code tells it to exceed the limit switches? I’m not sure if the problem is with the g-code, the limit switch, both, or something else entirely.
They aren’t limit switches - they are homing switches. There is a mode in GRBL (the control board) to use the homing switches as limit switches, but it is unsupported by Carbide.
Running into the limit switches outside of the homing cycle will not trigger any actions by either CM or GRBL.
I’m using Fusion 360 (which I am far from a pro at), and I have the clearance height set to .4", the retract height set to .2" and my zero is set to the top of the stock, which is 2" off the waste board. I just measured from the bottom of the bit to the wasteboard, and it’s 2.75". The way I understand the safety/retract heights in Fusion is the z-axis shouldn’t raise past 0.4" above the zero, which is 2" above the wasteboard.
That is helpful, and I wasn’t aware of that. It’s interesting that carbide didn’t incorporate that into the design, as it would prevent crashes on at least one extreme of each axis.
Am I correct in thinking that if my part is 2" tall and I have my retract height in Fusion set to 0.4" that my bit shouldn’t ever raise more than 2.4" from the wasteboard or 0.4" above the z zero if that is set to the top of the workpiece?
I’m struggling to understand why the z-axis is trying to raise so high and I’m not sure if it is something I’m doing wrong with the programming or if I’ve set something up wrong.
The end of the tool will only move 2.4”; however, Z axis limit is not relative to the end of the tool. With a long tool you may already be 2” or more into Z travel even at the wasteboard.
That is what I thought - so my tool is at 2.8" above the wasteboard when it’s initialized (almost at z-axis limit), so in theory it shouldn’t be trying to move past the z-axis limits. Clearly something is going wrong, either with the gcode or with some parameter that’s set. I’m no pro at deciphering gcode, but here is the code is crashing at line 22 each time. Here is the code up to and including the line it crashes at:
%
(adaptivegator)
(Machine)
( vendor: Carbide 3D)
( model: Shapeoko XXL Pro)
( description: Generic 3-axis)
(T1 D=0.25 CR=0 - ZMIN=1.5028 - flat end mill)
G90
G17
G20
(When using Fusion 360 for Personal Use, the feedrate of)
(rapid moves is reduced to match the feedrate of cutting)
(moves, which can increase machining time. Unrestricted rapid)
(moves are available with a Fusion 360 Subscription.)
G28 G91 Z0
G90
(Adaptive1)
T1 M6
S18000 M3
G54
G0 X-0.0254 Y-0.2874
Z2.6
Anyone see anything that I could have setup wrong?
I tried adjusting some settings in Fusion and generating new gcode. Same things happens right after tool change (z axis raises and crashes at top), then it plunges down to begin cutting but doesn’t because the bit is approximately 1/8" above the workpiece top for all the cuts. I’m not sure if this has something to do with the crash or if there is another setting wrong. In case it matters, this is an adaptive clearing operation for a 3D carve on wood.
If your stock is 2" thick, and you’re setting your z zero to the top of stock, then when you command it to go to Z 2.6, it tops out your z travel. I think you need to re examine your model setup in Fusion 360 and verify where your Z zero set. It sounds like it may be set at the bottom of the model, and you’re setting the zero at the top of the model.
That makes sense to a degree, and I’ll check into that. It is very possible that something is set incorrectly.
If the z zero was set to the bottom of the workpiece in fusion but the machine was set to the top of the workpiece, that would definitely explain exceeding the z-limit. What still doesn’t make sense to me is that after it does that, it lowers to about 1/8” off the top of the workpiece and starts running the program without cutting anything. I would have thought I’d the zero was set incorrectly in fusion, that it would try to dive through the workpiece.
I’ll report back with what I find - I appreciate the help and advice!