In a recent thread that I started, I mentioned that I would be switching to an Arduino, as a CNC controller, because of it's ability to run GRBL CNC software, and use the Propeller for a user interface. From a tired persons point of view, this is probably a good route to go, BUT there is one main limitation. GRBL is currently limited to three axes, which is perfect for three axis machines, but what about a fourth?
In the thread mentioned above, which is located here: forums.parallax.com/discussion/166284/cnc-the-new-plan-any-feedback/p1
There's a very functional CNC controller (all Propeller) recently made by a customer of ours that runs G code.
If you're interested in being connected to him please drop me an e-mail firstname.lastname@example.org. We should consider rallying behind his product if it's suitable for a number of our customers. At my first look, it certainly is.
The controller really is not the issue, because the Propeller can easily be used as a controller. The problem is reliable, understandable, and configurable software, which has community support. This particular issue has been my stumbling block for years.
In another thread, I present and describe a CNC controller, which should work well for a 3D printer or a four axes CNC machine. However, there currently is no completed software available to utilize this controller. And of course, this is always somewhere in the back of my mind. This thread can be found here: forums.parallax.com/discussion/160739/new-attempt-3d-printer-controller-and-firmware/p1
The new machine that I am building, will have a total of six steppers motors, for various tasks, and of course, all of these motors will need to be controlled, and as of yet, I still have no perfect plan for controlling these motors. I believe my best option at this point, is to move forward with the Propeller + Arduino + GRBL plan, but I still know with all my heart that the Propeller chip would make a nice controller without Arduino, so once again, I have been searching for and looking at various documents pertaining to interpolation, multi-axes syncronization, and CNC control.
A while back, during some previous research, I came across a document titled "Multi-Axis Synchronization", which was authored by John Rathkey, from Parker-Hannifin, Compumotor Division. This document can be found here: parkermotion.com/whitepages/Multi-axis.pdf
Now I must admit that my reading comprehension is not the greatest, so I have studied this document several times. And as I study other control schemes and software, I am always drawn back to this specific document. Over time, I have weeded out and sorted what I believed were the key aspects of the document, but then always returned to the original, for a fresh look. After reading it again this morning, I believe I had an epiphany, which should have been obvious from the first time I read it. In this document, John Rathkey discusses the mechanical approach to synchronization and the electrical approach to synchronization. Even though I was reading the document over and over, I always just glazed over the mechanical approach to synchronization and analogies thereof, but this time it hit me.....
To achieve multi-axis synchronization, the software must run just like a set of gears!!!!
And this software gear set, must support gears of different ratios!!!!
The master gear sets the pace, and the following gears remain synced at their specific ratio!!!!
Now what would be the perfect microcontroller for creating this software gearing? The Propeller of course, because it already has cogs :)
I hereby present the idea of Propeller Gear CNC software:) Am I crazy?