The problem: Mill suddenly decided to dig deep into the part I was machining. Drove the bit in and I quickly killed the process. I was just finishing a production run of engraving (0.001 mm) one pass into 20 brass plates. The last run the machine punched the engraving bit right thru the brass plate into the wood block. I was using Openbuilds Control. I had no problems with the previous run. Any suggestions on where to start looking at what went wrong? Thanks in advance.
does your machine have home switches and GRBL is set up to use them, ie you are forced to home by the alarm state at turn on, before you do any work?
no, not 'helped', I just need to know so I can give you the correct answer. In short , you need to 'fake the home'. (details of how to do it are there) in long: When the controller is turned on or reset (either the button, or when the software connects it resets) AND there are no switches and homing is not set up, it says to itself "fine, right here is machine home". So, it could be anywhere. The problem with that is there is now no way to do safety moves, we need to safely raise Z so we can move to the start of the cut with the tool well up out of the way of clamps and so on. There is an industry standard that says the Z home shall be as far up as Z will go, Z+ in other words. So if you always turn on or reset with Z up as far as it will go, it will always work without scary plunges and will be safe too (if you are not scared of that 700watt router now you will be after you lose a finger ) The link above gives you all the details of how to do it, and how to make macros to help with doing it easily.
Excellent. Thank you very much for this info. I think I will also be installing the limit switches sooner than later.
I decided to install the limit switches and the blackbox controller. However, all steppers grind and slip when I try movement in any direction. Tried adjusting the voltage to the motors, double checked my sequence of wires per the diagram, and the security of the connections. All seems as it should be. Any suggestions on where to start troubleshooting?
Did you buy your motors from us and recently? If not, rather than color codes rather ID the coil pairs: docs:blackbox:faq-identify-motor-coils [OpenBuilds Documentation]
@Peter Van Der Walt That was it! Colors were reversed. Thank you so much for your quick response. Mill back working with limits!
I had the same rapid movement in which it drilled down into the work piece again. I ran probably 20 jobs and then in the middle of a run, the machine dropped its Z value into the work piece. Should I be homing the machine after each run or doing something in between jobs?
At the start, could be homing, but at the point it failed, are there any G53/G28, etc moves at the point in the file? If not:
So your Machine zero is moving, That happens when you run the home sequence, or when GRBL resets. GRBL resets when the power comes on, and when the software connects. So if you close and restart OBControl, GRBL resets, and you need to re-home to tell GRBL where home is. While we don't have all the features of a pro controller as illustrated in the video below, there are things we CAN do to crosscheck before a job starts, After homing and then setting zero for this part on this material, hover your mouse over the display box for the Z number. The Machine Coordinate will pop up. Make a note, mental or otherwise, of that number. Now, between jobs, you can check that number and make sure it has not changed significantly. What is significantly? If you are running the same job across many bits of raw material held in a jig, then it will not change unless you reset Z0 for some reason, maybe if the material is varying in thickness. But the change should be within the range of material variations, maybe 1/16" or 1mm or so. If it jumps by 10mm+, then rehome and rezero before running the job! I know this video uses things we don't have in our software, but the important thing is the thought process "what can I do to ensure this works correctly"
Peter in the video also does a little 2 line buttsaver at the start of every program Code: G20 ; he uses inches G0 Z1 M0 You could insert this sort of thing as 'passthrough' code in Fusion360. It sets inch mode, then rapid Z to 1 inch away from Z0 (assuming it is top of stock), then pauses with the M0, then he compares that to his 123 block, then click run job again. You would have to do this in whatever measurement system you are using, DO NOT MIX UNITS IN THE SAME FILE. (you have been warned, not because it doesn't work, but because we are trying to prevent crashes, not cause them).
Yeah, I saw that. Probably safer for most to stay in metric and use 25.4mm. To make sure I have the right G54 Z0, correct G43 TLO pulled up (M6 doesn't auto-issue a G43, and Fusion doesn't insert one until after the first rapid move, which seems... not ideal, but I haven't looked into moving it in post setup yet), and an accurate TLO set, I just jog down to just above the surface and make sure it looks like about 0.5mm- I use a 0.5mm shim to do all my Z setting for the time being, so I have a pretty good visual of it- or whatever the DRO says. I find the smaller gap easier to gauge and the manual move to be safer, if I missed anything. Usually if I'm off by about 0.2mm/8 thou or more, I can see it. Less than that and it likely doesn't matter, at least for op-1s; I'm rarely starting with tiny tooling and usually have more than 0.2mm of extra stock in the CAM setup. Figuring out a pre-flight sanity check that works with your workflow when you do a lot of onesie-twosie parts is super important though.
