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IndustryArena Forum > CNC Electronics > CNC Machine Related Electronics > Need help with a CNC controller conversion
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  1. #1
    Join Date
    Aug 2006
    Posts
    281

    Need help with a CNC controller conversion

    What would be a good starting point for me to convert my CNC system to a newer/smaller/more flexible system? The current controller is a Bandit and it's fairly capable but not what I want in the long run. I don't know how practical it is to do a full conversion but looking at some of the systems out there it seems quite affordable.

    The servos are in pretty good shape so I'd prefer to not replace them but I imagine they will require a pretty strong system. I don't mind assembling a custom system with some basic wiring/assembly but I really want a set of components that are meant to work together. This includes software. I was looking at Gecko G340 motor drivers and G101 controller...but I'm not sure of they are truly up to the task. Does any software work with this system currently? What am I still missing? It seems like there should be some serious powersupply still needed. Any good tutotials? I'm looking for something around $1,000 if possible.

    Any suggestions?

  2. #2
    Join Date
    Aug 2006
    Posts
    281
    Well, I didn't get any replies ...that's OK. I wasn't really ready to pull the trigger.

    I'm starting to collect components needed for my migration now.

    I'm still planning on using Gecko G320's and a G100 or 101 to control it. I have to make a few calls to confirm that Mach3 will work with it but I see a lot of people using the grex so it must work with something.

    It appears my servo motors can be re-used. I wasn't sure how they spec'd out so I just measured the voltage while running - on a rapid move they were at 80 VDC (about 48v when holding position). Now, just for clarification - I only tested DC voltage from one of the two power wires to machine case ground. Hopefully it's not any type of floating ground system (probably not). I couldn't measure amps without cutting wires (not ready for that yet). Plus I'm guessing at 80 vdc, it's minimal unless it's under a serious load.

    I still need a lot of help though. Here are my key problems:
    * The encoders I have aren't reuseable. So I need to find <50ma encoders with a good resolution and cheap. Any suggestions?

    * Resolution on said Encoders. Currently they're connected to the handwheels, not the motor and I'll probably keep it that way (all the mounts are already done and built well). The ballscrews are 1/5" pitch. The current controllers maximum resolution is .0001. I can feed it .0001 and it seems to move the handwheel appropriatley. I'm not sure how accurate it is in that range but I don't think I want to lose resolution. My guess is it will need 2000 lines. Is this getting carried away? 500 lines seem the most common.

    * 80 vdc...Transformer. Suggestions? My experience with transformers was always with 12v. Should I transform from 230v instead of 110? I have 3 phase coming into it now so at this point the house wiring is done eitherway. Sources? I'm used to the old styles housings on trans. It seems most people nowadays are using ones shaped like a coil. Anything different with these?

    I guess that's it for now. I'm still working on the buttons and features of the front control panel. I'm not entirely sure how the digital/analog inputs work on the Grex and how well they integrate with Mach 2/3. I'd like to have the basic digital controls echo'd with buttons (CW,CCW,Stop,Mist) and I'd also like to have a few analog or encoder inputs (feed rate, jog wheel). I'll need to investigate these a bit though. I'm thinking that it'd be pretty simple so I could probably build a small handheld controller.

  3. #3
    Join Date
    Aug 2006
    Posts
    281
    Ok guys...any help here would be nice.

    I found this:
    http://cgi.ebay.com/80V-10A-34V-2A-P...QQcmdZViewItem

    The big mystery for me right now is how can I tell what amp draw my servos will require? It seems like this would power all three of my motors OK unless all three were under a heavy load all at the same time.

    For sure Gecko's aren't supposed to get more than 20 (I think)...so I wouldn't want more than 20 amps, right?

    Opinons?

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