Hi All,
The assembly and re-design for the parts that I decided to cut on CNC goes ahead, even if slower than I would like - yes, it is true, I have to burn the midnight oil for this project, and the weekends are invaluable for the progress. Nevertheless, there is some advance, which I wish to share here.
Firstly, I just have to say how amazed I am to see the amount of work, the details and thoroughness that @Chris Annin put into this project – thank you so much, Chris! The slight modifications and additions that I made are not a critic, but rather adaptations to a different process, and some different perspectives approaches. By no means the big picture is not changed at all, all the functionalities will still be the same as designed. Form a different perspective, I know that Chris’ approach is cheaper and sometimes more efficient, but I don’t intend to show a cheaper design, but rather an adaptation to a somewhat different approach.
Here we go…
I made the “J1 base enclosure” cut from a single piece of Delrin. I added a bottom part / cover, with captive M4 nuts, so the J1 assemble can be fully closed.
I also redesigned the break-out box section, to make it easier to be CNC processed. It is a tad smaller and narrower, but that means it will be more difficult to assemble the wiring – not a problem for myself, as I am dealing in my trade with microelectronics design and prototyping.
I created a protector for J1 limit switch, to avoid damaging it in care the turret turns more than expected.
I also modified the J2 protector, the “J2 Stop” detail was just a bit too complicated to be processed by CNC – of course, this is just an alternative way of achieving the same function. I will redesign the “J2 Stop” detail to make it decorative.
I also advanced on the electrical assembly. I decided to install everything in a 6U wall mounted 19” rack, and I am just adapting the internals for now. I made DIN rail adapters for the drivers - ok, I know that it might be possible to find them ready made, somewhere, I just could not find something that was “off-the-shelf”. I also prepared the field for installing all the other components in the same rack, the image with the drivers is not showing that there are three DIN rails in the same shelf, plenty to support all that’s needed for AR4.
I also adapted the connector’s panel for the rack.
It might look odd that I have 8 drivers instead of the usual 6 or 7. In fact, I do have the configuration prepared to drive a 7th axis (the “rail” as described by Chris), for which I added a closed loop driver (CL57T) that will support a NEMA 23 closed loop stepper motor – this might look as an overkill, but I did have it at hand and decided to use it. The 8th driver’s story is a bit different: the DM542T drivers are able to support 50VDC supply, only that the DM320T, used to drive the NEMA 11 stepper motor supports 30VDC maximum. Using DM320T driver is the reason to use a 24V power supply only, when, in fact, the motors can benefit from a higher voltage – greater acceleration and higher maximum speed are achievable. One might ask the question on why not use a DM542T driver for the NEMA 11 motor – well, that’s impossible, as the minimum current that DM542T is configurable to is 1A, while the NEMA 11 motor accepts maximum 0.3A. My intention is to modify a DM542T to supply less current, but that’s not an action that Chris could recommend, nor the supplier of the drivers can support. I will try the modification, if that works I will then omit the DM320T driver, and let you know how that was done, but at a later stage.
I’ll keep posting the progress here.
Have great success with your builds!
L.E. As promised, please see attached the STL files for the parts already made and tested.