I’ve been using the Onefinity CNC for about 1 year now and this is the first time that anything like this has happened to me. While cutting a project today, I had the z-axis continue to cut down through the project and into the waste board. Common sense would dictate that I told the machine to do that - so i’m hoping you can help me solve the mystery on what I did incorrectly - or if there is something more sinister afoot.
Before we get too far into the story (I tried to include as much information as possible… strap in, it’s a bit of a read), here is a little bit of background:
- Onefinity Wordworker
- Vectric VCarve Pro
- Makita Router
- 1/4 Amana Upcut bit, 120 inch/min
So, first off - for those of you using VCarve, here is my Vcarve file. 3Round.crv (2.5 MB) Take a look, poke around - see if anything is “off”
For those of you using other software, here are some of the screen shots of the project. The wood was 0.675" thick.
In that project, I have a profile pass to cut an outline around the project at a depth of 0.68" thick. This will (intentionally) go 0.005 into the waste board.
Each of the 3 passes were broken up as such (confirmed in the GCode posted below). With the final depth of cut at 0.68" as seen at both the top of the “Specify Pass Depths” image and “2d Profile Pass” image.
Using that information, I created 3 tool paths (as seen in the VCarve file.
- Profile Pass
- Roughing Tool Pass
- Finishing Tool Pass
Unfortunately, I didn’t get pass the profile pass before wrecking my router and creating a hole in my table.
In theory, the machine only does what it is told to do - so lets talk Gcode (full file if you want to follow along):
3Round_1-outline_UPEM_0.25.ngc (18.4 KB). Here are the most pertinent parts -
Part 1 - the Setup
- GCode sets the correct plane and tells the machine it should be in inches. Verifies that the spindle is up to speed with the on screen button.
- From there, you see it set F50.0 (50 inch/m), drop from Z= 0 to Z= -0.2267 and sets F120.0
% (VECTRIC POST REVISION) (14915DE88D57FEB54FDB7F235745EEBE) T105 G0 G17 G20 G90 G40 G49 G64 P0.0001 G0Z0.2500 G0X0.0000Y0.0000 M3 S18000 M0(MSG, Click 'Continue' when the spindle is up to speed) G0X0.7542Y0.6107Z0.2000 G1Z0.0000F50.0 G1X0.7288Y0.6417Z-0.0182 G1X0.7043Y0.6732Z-0.0363 G1X0.6805Y0.7053Z-0.0544 G1X0.6576Y0.7380Z-0.0725 G1X0.6355Y0.7712Z-0.0905 G1X0.6143Y0.8049Z-0.1086 G1X0.5939Y0.8391Z-0.1267 G1X0.5744Y0.8739Z-0.1447 G1X0.5557Y0.9091Z-0.1628 G1X0.5379Y0.9448Z-0.1809 G1X0.5210Y0.9810Z-0.1990 G1X0.5049Y1.0176Z-0.2171 G1X0.4970Y1.0371Z-0.2267 G1X0.4898Y1.0547Z-0.2267F120.0 ...
Part 2 - the calm before the storm
- First round pass completes without any issue.
- Next, you see it slow down to 50in/m as it does its next drop from Z=-0.2353 to Z= -0.4533 and then speeds back up to 120 inch/min
... G1X0.4970Y1.0371 G1X0.4898Y1.0547Z-0.2353F50.0 G1X0.4755Y1.0922Z-0.2535 G1X0.4621Y1.1302Z-0.2718 G1X0.4496Y1.1686Z-0.2900 G1X0.4380Y1.2073Z-0.3084 G1X0.4273Y1.2465Z-0.3268 G1X0.4176Y1.2860Z-0.3452 G1X0.4087Y1.3259Z-0.3638 G1X0.4008Y1.3662Z-0.3824 G1X0.3938Y1.4068Z-0.4011 G1X0.3877Y1.4477Z-0.4198 G1X0.3826Y1.4883Z-0.4384 G1X0.3789Y1.5211Z-0.4533 G1X0.3767Y1.5406Z-0.4533F120.0 G1X0.3768Y1.7683 ...
Part 3 - where it all goes south…
- In theory, the Gcode is telling it to now slow down to 50in/m, go from Z-0.4622 to Z-0.6800, and then speed back up to 120.0 in/m and then continue the cut. However, it continues to decrease at a constant Z level until it cuts the spoil board and runs into the aluminum t-track.
- BUT, notice that the Gcode tells it to only go down to Z-0.6800 - and I don’t know why it kept going negative Z.
... G1X0.3789Y1.5211 G1X0.3767Y1.5406Z-0.4622F50.0 G1X0.3768Y1.7683Z-0.5655 G1X0.3847Y1.8331Z-0.5951 G1X0.3938Y1.8979Z-0.6247 G1X0.4053Y1.9628Z-0.6546 G1X0.4172Y2.0176Z-0.6800 G1X0.4192Y2.0267F120.0 G1X0.4355Y2.0896 ...
Here is the aftermath in all it’s glory… After pulling the project up and inspecting the damage. You can see that it completed the first two passes without any issues.
Looking at the continuation of Z-Axis decline…
You can see how as it started ramping down near the X/Y=0 point, it continues to ramp down through the spoil board and into the aluminum t-track. At 120in/m it was through the spoil board and into the t-track only a couple of seconds. Upon hitting the t-track, it stalls the router (and burns out the brushes) and ruins the 1/4 bit.
Ok… so, router, bit, and spoil board destruction aside, what I am trying to figure out is what happened so that I don’t do it again.
To get a couple questions / answer addressed upfront:
- I’m not a G-Code expert, but it doesn’t look like the Gcode was telling the CNC to continue to drop below Z-0.6800.
- I’ve run dozens of projects like this using V-Carve to create Gcode and this is the first time I’ve had this happen.
- This is the only copy of Gcode I created, there are no additional Gcodes to have run a file that had incorrect parameters
- No, and I hope this is obvious, but I didn’t destroy my spoil board on purpose
- After the crash, I ran the exact same file again (to ensure it wasn’t a Gcode file issue) without a bit in it without restarting the machine. It did not have the same issue, it performed normally.
Any ideas what went wrong? Anything I can do different in the future? VCarve Bug? Onefininty Bug? User error? I’m open to anything and I appreciate you reading through this and offering any assistance!