1. #1
    Hi all,

    I have been researching in preparation for building my first DIY CNC router for the last couple of months. I have pretty much made the decision to start by buying the UIM2901-5A MACH3 breakout board from Zapp Automation, however I was just wondering if any of you have any experiences of this board? It would be useful to know if any of you can help with this should I get stuck.

    Also, while browsing the various CNC part suppliers on the net I noticed that it is possible to get breakout boards that use a USB interface instead of the LPT parellel port. Would any of you recommend using these from the start or would it be better to stick with LPT for my first machine? The USB boards seem to be a bit more expensive, however is this worth it for the added inputs/outputs? Also how compatible are these boards with Mach 3?

    Any advise you can give will be gratefully received, especially before I part with any of my hard earned cash!


  2. #2
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Current Activity: Viewing Has been a member for 8-9 years. Has a total post count of 1,303. Received thanks 123 times, giving thanks to others 3 times.
    The main benefit of using USB, is it removes the uncertaintity of LPT ports, and is generally easier to set-up, however they do have some limitations (for the more popular interfaces, they mostly relate to lesser used features that won't affect the majority of users)

    You can always go for LPT, then change later, as most Mach compatible USB interfaces can interface to LPT breakout boards.
    There are also ethernet based interfaces to consider.

  3. #3
    If you can afford a USB, PCI or Ethernet controller then it pretty much guarantees a good stable system, but this comes at a relatively high price.

    The breakout board you linked to is rather expensive, why have you chosen than one in particular?
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  4. #4
    I think you may be confusing or miss under standing the breakout boards (Bob) your seeing. Some bob's use the Usb to take 5V power for the various features they provide, (Opto-isolation etc) but they still use the LPT for sending/recieving signals to control software.

    If your seeing cards that only have USB then they will most likely be motion control devices which eliminate the need for LPT.
    Often these cards still need a BOB to make connections to inputs & outputs( I/O's ) easier. The advantage of a motion control device over the LPT is much cleaner and stable signals are sent to the drives resulting in much smoother operation and often higher Acceleration/speeds can be achieved. The signals produced are much more stable so far less errors from missed or dropped steps, esp at higher feed rates.
    The over advantages to motion control devices is they take all the work away from the Control software so tend to need much less computing power so can be used on cheaper computers and Laptops which with some control software like Mach 3 Laptops are a big No No.!!

    Really the basic funtion of a BOB is to make I/O connections that bit easier and when using opto-isolated versions that bit safer for the computer.
    Decent Bob's provide over features like, relays for turning thing on/off or like the one you linked to they provide PWM or analog ouputs for directly controling the speed of spindles when attached to VFD's etc.
    Other feature are providing charge pump circuit so the motors etc don't recive any signals untill the control software (Ie Mach 3) has full control therefore machine starts up in a safe state.!

    While Not advised it is possible to not use a BOB at all and wire direct to the LPT cable.!!

  5. #5
    Many thanks to you all for responding to my questions. To be honest the choice of boards is a little overwhelming for a newbie like me and I don't have a solid answer as to why I chose this one. It just looked like a reasonable card with a number of features that I could make use of.

    If there is a cheaper card on the market that would get me started, is available in the UK and will get me started then I'm open to your advice.


    PS - At present I see my machine having three axis with the usual limit switches, a standard router that I would like to be able to control from the Mach 3 software (however I would like the option to upgrade to a proper PWM controlled spindle later) and an additional relay for controlling a dust extraction device (probably an old vacuum cleaner for now).

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