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  1. #1
    Join Date
    May 2011

    Newbie Advice on VFD conversion

    Hi Everyone,

    My first post so please excuse any ignorance.
    I have a HM52 mill from Hare & Forbes. I wish to convert it to 3 phase with VFD control for obvious reasons + I wish to increase the kw from standard 1.5 to 2.2.

    After this I wish to do a CNC conversion run by MACH3 and have followed Chich's great work in his thread.

    My question is I have found this VFD unit on eBay
    SAJ 2.2KW VSD VFD inverter 240V variable speed drive (eBay item 180660166513 end time 29-May-11 11:21:34 AEST) : Industrial
    and need to know if it could be controlled via MACH3. I have asked the supplier and he doesn't know much about MACH3 so was hoping someone could look at the specs on the ebay listing here http://www.fennecmachinery.com.au/SA...M%20manual.pdf
    and let me know if you believe it suitable to be controlled by MACH3.

    Don't know much about the electrical side of things but learning fast.
    Any help greatly appreciated.

  2. #2
    Join Date
    May 2007
    Let me start by saying I don't have a VFD in my setup, and have never even touched one...

    The problem is, VFDs typically can be controlled by a number of methods:
    • Digital inputs
    • A voltage from 0-5V or 0-10V
    • A current from 0-20mA
    • RS-485

    And with choice, comes confusion.

    If it was mine, I'd try to use an RS485 connection, since that's the most direct & feature rich interface. Problem is, it's not the "simplest" way - you'll need a PC to RS485 converter - and then deal with the software aspect (MACH3 configuration, etc).

    I'm no expert, but it seems like a fulled feature & suitable unit.

  3. #3
    Join Date
    Nov 2007



    Can't give specific advice on that VFD, had trouble trying to download the manual.

    Mach3 can control a vfd. I'm converting a lathe right now. I am using a break out board (BOB) from cnc4pc, but other companies offer similar BOB.

    The BOB has a 0-10v analog output for controlling the VFD.

    Have you found a 240v 3 phase motor to install on the mill? I'm just started looking for one for my lathe. Most 3 phase motors in Australia are 415v, 240v are out there just might take a little more work to find.

    Have a look at a mates website for some detail on the mach3 setup:

    My CNC Adventures

    Don't see where in Australia you're located, but if your in Perth I'm having some mates over next saturday to show off my lathe and your welcome to come out and see it.



  4. #4
    Join Date
    Apr 2007
    Hi Mate,

    I have the same mill that I been procrastinating over for years whether to convert to cnc.

    The simplest was to turn the spindle on/off would be switch a relay via mach3 (section 4.6.1) which is wired to the multi input terminal of the VFD, terminals MI1-DCM, then just program MI1 as fwd/stop. This means you choose the desired speed manually. You would still need to set your ramp up/down speeds as normal and just add a delay to mach3 to allow the spindle to reach full speed before cutting

    Alternatively from the mach 3 manual using PWM is possible to control the spindle speed VFD via the 0-10v voltage input on the VFD using a PWM converter

    4.6.3 PWM Motor Control
    As an alternative to Step and Direction control, Mach3 can output a pulse width modulated signal whose duty cycle is the percentage of full speed that you require. You could, for example, convert the duty cycle of the signal to a voltage (PWM signal on for 0% of time gives 0 volts, 25% gives 2.5 volts, 50% gives 5 volts, up to 100% gives 10 volts) and use this to control an induction motor with a variable frequency inverter drive. Alternatively the PWM signal could be used to trigger a triac in a simple
    DC speed controller.

    Have fun

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