DIY build of a gantry milling machine with standalone controller and auto tool change
Stand alone controller DDCSV 1.1
Most of today's DIY CNC use some sort of interface cards and an (old) PC as controllers.
Not liking the idea to boot a PC, struggling with it's hardware in a rough environment (my work shop has no heater) and paying money for Mach 3 or similar, I jumped right in at the deep end and ordered a cheap Chinese stand alone controller, namely the DDCSV 1.1 from DDCNC including an MPG and a 24V 300W power supply. One reason was, that there seemed to be a "hacker scene" trying to pimp this piece of hardware at madmodder.com. After reading the huge amount of entries there things changed in February 2018: A forum at ddcnc.com opend and "Ytliu", obviously with deep internal knowledge moderated it. Not only that he answered questions, he also fixed bugs and put updates on the web to be used.
The image shows the controller labeled "RMHV2.1", which is identical to the DDCSV1.1, just labeled different as sold by Rattm Motors. Today (April 2019) newer versions of the controller (DDCSV 2.1, DDCSV3.1) exists, but except some smaller enhancement, the differences are not big. The firmware of DDCSV2.1 runs on the "old" 1.1 version and there is no real reason not to by the cheaper...
The 24V 300W power supply is a bit of overkill for the device (20W would be more than enough), but so I have spare power for extension, e.g. for the solenoid valves for the ATC and the water cooling motor for the spindle.
The biggest problem with this controller is it's documentation. It is okay for wiring up the hardware but it simply does not describe all the enhanced functions of this powerful controller. As a result, most of the controller users simply don't know, what it is capable of. But hopefully this will change in the near future: DDCNC agreed to write an enhanced description - we'll see.
From my point of view the following, undocumented features are most important:
- DDCSV is capable to perform macros using (and able to change) built in parameters and user defined variables.
- DDCSV is expandable via a simple serial interface for up to 32 inputs and 32 outputs easily accessible by G-code. I made extensive use of it when getting my tool changer to work.
- Using an USB-Hub, more than one memory stick and a normal USB keyboard can be used.
- Two extra buttons can be added, which can be set up to initiate user definable actions, when pressed. A nice feature for my my tool changer.
- The build in probe function, which can be easily enhanced to do auto probing, center probing,.... I used it together with the tool changer to do automatic tool length compensation.
All information I used where described in the DDCNC forum - it may take some time to read all the relevant articles there, but it is worth it! Also the DDCNC facebook group may be a source of information, but the chance, that you are more misinformed reading the messages than not reading them is high...
I use Fusion 360 to generate the G-code for the controller with the help of the post processor developed by Jay McClellen (www.brainright.com). After some fixing (look here) this post works fine. Jays original post can not handle multiple tools but adopting it to write out M6 Txxx commands (xxx=tool number) is not a big deal. Fusion 360 post processors use simple Java Script and it's DOM interface is well documented. If you are interested of my version of the post, drop me a mail.
I mounted the controller into an aluminum housing, which is connected by a 37 pin D sub cable to the control cabinet. The MPG is connected to the box by a fixed spiral cable. The box can be detached from the holding plane without tools.
On top of the controller the mentioned two extra buttons and an emergency stop button can be seen. The connector above the USB socket is for an extra probe (usualy unused, since the tool length probe is connected permanently via the control cabinet).
To conclude: Jumping right in at the deep end was not a wrong decision. DDCSV1.1 (2.1/3.1) is a fine piece of hardware/software for a reasonable price, which works well and avoids a PC near the machine.
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