I've started building the AR3 with some of the AR4 changes. I have both the Teensy 3.5 and now a Teensy 4.1. I have a number of encoders so I'm going to do it that way rather than use the StepperOnline motor/encoder pair. Same with a bunch of stepper motor drivers in the parts bin.
I've created Alibre PART files from the drawings which was a really useful way to learn how it was put together. Most of the bearings have arrived from various suppliers. And I'm pretty well done all the 3D printing.
To make the metal parts I'll first make patterns and then cast the rough blanks out of scrap aluminum. Then use my CNC mill and ELS controlled lathe to take them to completion.
Here are the first photos. I have my ducks in a row on the 3D printed parts.
Some more progress on the Teensy 3.5. I have CUI encoders run from 5V. The quadrature encoder puts out the 5V waveform which will ultimately overwhelm the Teensy 4.1 used for the AR4 version. The idea is then to use a voltage divider or a semiconductor that takes in 5V signals and translates them to 3.3V output. The active devices are important for really high speed signals.
In my case I've used a 6.8K and 10K resistor to divide the voltage and the signal is just under 3V and still can be used by the Teensy 3.5. Adjusting the AB scale lines a bit better shows the high levels are more like 2.9V.
To do this with my interface card I've added some strip sockets where I can insert either the resistor networks or just jumpers to connect directly. The center pin in each row is ground. The one closest to the screw terminal connects to that. The other connects to the Teensy.
Here's how it's wired on the bottom.
Now I can do an individual J4 axis calibration and actuate the switch to tell it the end of travel has been reached. After that the jog buttons move it on and off. I've got to look further into the Python code to verify that the encoder is actually being used for the jogging.
I have a bit more work to do on this and then I'll see if it's worthwhile actually laying out a PC board carrier for the Teensy's.