As time allows, I've made good progress on getting my setup working. Based on submitted feedback, I've added a Pokeys 57CNC motion controller board that communicates with the original JP-3163B stepper driver via a custom cable (see attached photos). I've been able to print mounts that still allows me to use the original controller housing, but I'm having a few issues getting smooth control over the CNC.
At this point, I can control the Pokeys board via Mach4 and when I send MDI commands, they're being transmitted by the Pokeys57CNC motion controller and relayed through the JP-3163B stepper driver. However, just doing a test on the x-axis runs, the motion appears to be jerky or not smooth when I use a feed rate less than 50. With help from an engineering colleague, I've been messing with the counts per unit (i.e., the steps per unit) for the x-axis motor, and while I don't know the exact specs of my leadscrews, I've pretty much got it dialed in to get the correct distance per input I provide in the MDI code. My problem is that I can't figure out why I'm not getting smooth motion when testing the x-axis.
I've convinced myself that this isn't a hardware problem because I have a direct drive setup and the stepper motor isn't physically slipping on the leadscrew. As I try to diagnose the issue, I've noticed that the jerky motion isn't consistent from run-to-run, but it is certainly much worse when I use a slow feed rate. Any feed rate less than 50 and I'm sure to lose distance moved because the motion hesitates at some point. In the attached video (
http://www.amazon.com/photos/share/LzcklOx62Hd6FQ00eDM10hM5eXv15WHFSIYEV0rsoyw), you can hear the hesitation (low hum goes away during hesitation). I tried to keep my phone still while recording, but there are places in the 30-second video where you can see and hear the problems I'm having.
Any ideas of what may be going on? Could it be that the Pokeys57CNC motion controller is sending commands to the JP-3161B stepper driver too quickly? If so, what would I need to change in the configuration? I didn't find an option in the Pokeys plugin config that allowed me to change the baud rate or even change the communication speed. When I used the Pokeys diagnostics tool, it appeared that the communication was never more than 25% of max, so I'm really at a loss here.
Any ideas?
Ryan