The CNC machine is functional.
I had been on a bit of a mission lately, to get the machine up and running. Among things that needed to be fixed, replaced, or installed:
– The router bearings were going out, so I upgraded to a Porter Cable 892
– A new router means a new router mount, which I saved some time and effort and bought from BuildYourCNC.com
– The new router needed to be modified to remove the variable speed controller, and have the Super-PID RPM sensor installed
– The Super-PID needed to have its case completed
– The SUper-PID needed a daughterboard to bring connections for Home switches and RPM sensor outside the case
– Hall Effect home switches and their magnets needed to be installed and cables built and run
– Z axis motor cable was faulty and needed replacing
– The cable carrier track was doing more harm than good and needed to be removed
The last time I attempted a cut on the machine, it failed midway through, and I decided that I was going to get the machine fully kitted out before I ruined any more wood.
Tonight, I had just a couple of last things to get done; I installed the Hall Effect switches, and replaced the Z-axis cable.
The Hall Effect switches have been a real pain to get running. First, I fried one while testing it. Then, after I’d built a new one to replace it, I found out that the switches were not wired up in a way that was going to work with the G540 inputs. They were pulling down the G540 input by several volts, even when not triggered, which was causing the G540 to register the switches as permanently tripped. I have enough extra Hall Effect chips to create a new set, but after several iterations trying to fix that problem, I decided to just buy pre-wired Hall Effect switches today, rather than go through the process of rebuilding the switches again.
The new switches also didn’t go right in; a small aside on wiring standards.
The Hall Effect chips are wired +5v,0v,signal, which is both non “standard” (relative to the ubiquitous “servo” connector signal, 5v, 0v), and also allows one to fry the chip if you hook it up backwards, which is exactly how I’d fried mine almost a month ago. I had built my whole system to use “regular servo cables”, but the daughterboard was wired to match the Hall Effect chips, so the wire colors on the servo cable didn’t match the signals going through it. It was all very off-putting, but it was working, and of course I’d just etched a new daughterboard yesterday afternoon, set up for 5v,0v,signal.
So the new pre-wired Hall Effect boards cross the pins around so they can be plugged into a “normal” servo port (like on an Arduino). Grr. So I briefly considered my options; either wire up a jumper cable, or re-create the daughterboard, or both. I decided to wire up some jumpers. And actually, now that I’ve done that, the wiring makes a lot more sense again; I just hook the stuff up so that the wires go where they’re supposed to, and all the colors match up with the pins they’re supposed to, and there’s no way to hook it up backwards (because I have keyed servo leads). Best part of all, the whole thing worked the first time I tested the jumpers. w00t!
I got the X and Y switches installed, and because I had a little dab of Sugru left over (I love Sugru by the way — I have about 4 layers of the stuff on each spot where the switches go 😀 ), I mounted up the Z-axis switch, too. Then I decided “what the heck”, and wired up another jumper and a looong Z-axis servo cable, and just like that, I had home switches on all 3 axes!
Hardly believing it would work, I fired up Mach3, and homed each axis. I had to flip a couple of “Home Neg” settings, but other than that, they all worked great. Seeing the little LEDs come on as the axes homed in was very satisfying.
I can now “Ref All Home”, and it drives Z to the top of its run (backs off a little when it hits home), then Y to the end of its run (backs off), and then X to the end of its run (backs off), and zeroes the DROs! So Cool!
With a repeatable home setting, I put in soft limits for all 3 axes, and tested the limit on the only axis I can do safely, Y. Ran it out to 48″ and it slowed to a stop right on cue.
With the axes homed, I decided to try out the new router under speed control. It worked flawlessly. Spindle on/off, S10000, S20000, S30000 all did their jobs. The RPMs and the requested speed are not quite right, but I’m pretty sure that’s a function of the pulley settings.
At this point, I just need to put in a collet and endmill, and load up some G-code!
And when the silly machine loses its place in the middle of a job, I can just re-home it, and keep going.
It’s been a long tough road, but I can finally say I’m ready to cut on the big CNC.