CNC Mill Conversion

[janz99]

Hi guys,

I have a G0704 mill that I am looking to convert to CNC and I was hoping to get some advice on some of the electronics to do the conversion.  Here is a run down of the major components, hopefully I can get some advice on weather this setup looks ok.

570oz X & Y steppers
906oz Z stepper

I haven't figured out what drivers I am going to use, so if you have any suggestions, it would be greatly appreciated.  I would prefer stand alone digital drivers and this point, unless there is a better alternative.  Your PDMX-137 power supply, will this be enough for my current needs/planned setup?

I am was looking at your PMDX-126 for a breakout board, and then using an Ethernet smooth stepper.  Would I need another board if I wanted to control spindle speed with the 126? For now I have the factory motor on the machine, but eventually this will be upgraded to a 3phase motor and VFD. 

I would also like to build a 4th axis for this machine down the road. I figured I would mention this in case in makes a difference in component selection.  Other then home/limit switches, an e-stop, cables and wiring, is there any other key components I may be missing? 

Thanks
Ryan

[Steve Stallings]

The motor sizes that you list seem appropriate for the machine, assuming
a ball screw conversion.

There are many drivers that will work well. Gecko G203V units are popular.
Many of the Chinese units are fine. You can purchase on eBay or, if you
want some local support, try Automation Technologies. I would recommend
avoiding any of the units based on the TB6600 or TB65xx series driver chips.
The available units typically quote the absolute maximum (self destruct limit)
specs as regular running specs, and then do not provide adequate protection
or heatsinks.

A PMDX-137, with an appropriate user supplied transformer, can run this
machine and others up to Bridgeport size. There are also complete power
supplies available from Antek that many people use.

On/off spindle control with the relay on the PMDX-126 works, but you must
defeat the "restart lockout" on the G0704's spindle driver. Variable speed
control is possible but the wiring is a bit more complicated, an external
contactor is recommended, and the "restart lockout" still needs to be defeated.
To do this we recommend the PMDX-107  and PMDX-ContactorMD20-120. This
small contactor can be controlled directly by the PMDX-107. If you later find
a motor and VFD you can fit to the machine, the PMDX-107 will control the VFD.

A 4th axis is no problem, just select a power supply capable of running it.