1. #1
    Well, this is my first post (about my first cnc), so hello.

    Am wanting a cnc to make pcbs, and came across this one:
    http://www.amazon.co.uk/gp/product/B...A2D0WLNIN2PEPT
    It seems to have slightly better build quality than some of the other generic 3020's.

    As have understood, the autolevelling can be achieved by connecting leads to the spindle and pcb surface, the result is fed back to a parallel port pin.
    Have not seen mentioned exactly which PP pin should be used - I assume there are parallel port connections not used by the cnc controller and can choose any of those.
    Just wanted to check this is doable - I doubt it's possible to make a quality pcb without the autolevelling - and the cnc will not be any use to me if it cannot do the pcbs.
    The only other slight worry is using a PCI card for the parallel port - am thinking about this one:
    http://www.amazon.co.uk/gp/product/B001Q7X0Z8?psc=1&redirect=true&ref_=ox_sc_act_titl e_1&smid=A3P5ROKL5A1OLE

    Thanks...

  2. #2
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 3 Hours Ago Has been a member for 4-5 years. Has a total post count of 1,000. Received thanks 170 times, giving thanks to others 5 times.
    Can't help with the parallel port pin question as I'm not using this on my own machine, but I think you should be ok with the parallel port adaptor. I'm using one of these with LinuxCNC and it works fine. I suspect that it is very similar to the item to which you linked - the supplier was out of stock of parallel-port only cards when I needed it. The thing to avoid at all costs are usb-to-parallel port adaptors as they completely destroy accurate pulse timing.

  3. #3
    Quote Originally Posted by iBeta View Post
    The only other slight worry is using a PCI card for the parallel port - am thinking about this one:
    Problem with PCI cards is that it's a lottery.? (I'm speaking in terms of Mach3 Here) Some work fine some don't. My suggestion is go with one that others have used and know works. Like what Neale shows.

    Or better still Don't bother and buy Uc100 from here and do away with it. This is a good way to go about avoiding the PP issues, It's not the best motion control card in the world but much better than PP, easy to fit and cheap-ish. http://cncdrive.com/UC100.html

    Oh Hello and Welcome to the nut house. .
    Last edited by JAZZCNC; 20-11-2015 at 05:32 PM.

  4. #4
    Neale's Avatar
    Lives in Plymouth, United Kingdom. Last Activity: 3 Hours Ago Has been a member for 4-5 years. Has a total post count of 1,000. Received thanks 170 times, giving thanks to others 5 times.
    Just to amplify what Jazz has said - I'm using my PCI card with LinuxCNC and it has not given me any problems. However, my current router is a very low-performance machine. My workshop PC where this is installed is dual-boot Linux and Win7. I have booted Windows with the trial version of Mach3 and it appears to detect the parallel port but I have not fully tested it. That's mainly because I plan to use an external motion controller with Mach3 for my next router to avoid any possibility of problems like compatibility, pulse timing, etc. The parallel port card will probably work. The external motion controller will definitely work. It's a personal decision!

  5. #5
    Ok, thanks for all the information.
    Think will try the PCI card first, then see (er actually already ordered it with the machine so no choice now). Did wonder how an external motion controller can be 'better' than PP. If the mach3 is giving timing pulses via the parallel port, how can these be improved upon by an addon controller?
    If I do end up having to use an external motion controller, can the autolevel signal still be connected directly to the PP? From others, it seems making a reliable pcb is impossible without autolevelling.
    On edit:
    found this: http://lab.whitequark.org/notes/2014...dden-features/
    which has the PP pinouts - 15 is the probe input. It also has a hack to control spindle speed via software.
    Last edited by iBeta; 21-11-2015 at 01:31 PM.

  6. #6
    Quote Originally Posted by iBeta View Post
    Did wonder how an external motion controller can be 'better' than PP. If the mach3 is giving timing pulses via the parallel port, how can these be improved upon by an addon controller?
    If I do end up having to use an external motion controller, can the autolevel signal still be connected directly to the PP? From others, it seems making a reliable pcb is impossible without autolevelling.
    It's all about the Speed and Quality of the pulses. Technicly Mach3 PP driver is breaking all the Rules in relation to Windows. It basicly runs has a Virus in the background and windows knows nothing about it, in fact it kind of controls windows.!! Many Boffins told Art fennerty Mach designer it couldn't be done.!! . . .So he did it anyway.!!!
    The done shot is that because it's software driven it's Timing/speed limited and to some degree quality limited.

    Ex Motion control cards have dedicated hardware designed to optimise the task and provide crystal clear pulses. This means they can output much faster and stable pulse streams. They also relieve Mach3 of many funtions so lower the work load quite a lot.
    The upshot is No missed steps due timing issues. Faster and smoother movement because the frequency of pulses can be much higher and higher quality pulses make for smoother running. Often people are suprised when they change from PP because the noise from the steppers changes.!!

    You'll still be able to use Leveller with EX Mo because they take over the dutys of Inputs/outputs. Often doing a better job due timing issues etc and providing more of them.
    Honestly is your using Mach3 don't bother with the PP. ( Linux is differant because it hasn't got Windows to deal)

  7. #7
    A reasonable solution to levelling is to machine a pocket to suit your board size in some scrap MDF, and fix your PCB in it. If you are doing large PCBs, I would have them made as cutting off copper is a slow business.

    Then again, if you are anything like me and only find your design errors when testing the built circuit, if you have cut your own board there is less intensity to that 'Oh F***!' moment.

    Rob

  8. #8
    Quote Originally Posted by JAZZCNC View Post
    It's all about the Speed and Quality of the pulses. Technicly Mach3 PP driver is breaking all the Rules in relation to Windows. It basicly runs has a Virus in the background and windows knows nothing about it, in fact it kind of controls windows.!! Many Boffins told Art fennerty Mach designer it couldn't be done.!! . . .So he did it anyway.!!!
    The done shot is that because it's software driven it's Timing/speed limited and to some degree quality limited.

    Ex Motion control cards have dedicated hardware designed to optimise the task and provide crystal clear pulses. This means they can output much faster and stable pulse streams. They also relieve Mach3 of many funtions so lower the work load quite a lot.
    The upshot is No missed steps due timing issues. Faster and smoother movement because the frequency of pulses can be much higher and higher quality pulses make for smoother running. Often people are suprised when they change from PP because the noise from the steppers changes.!!

    You'll still be able to use Leveller with EX Mo because they take over the dutys of Inputs/outputs. Often doing a better job due timing issues etc and providing more of them.
    Honestly is your using Mach3 don't bother with the PP. ( Linux is differant because it hasn't got Windows to deal)
    Ah, thanks... I'll get a uc100. You guys have probably saved me a lot of problems, and I guess it don't take too many ruined 200x200 double side'eds to pay for it.

  9. #9
    Quote Originally Posted by cropwell View Post
    A reasonable solution to levelling is to machine a pocket to suit your board size in some scrap MDF, and fix your PCB in it. If you are doing large PCBs, I would have them made as cutting off copper is a slow business.

    Then again, if you are anything like me and only find your design errors when testing the built circuit, if you have cut your own board there is less intensity to that 'Oh F***!' moment.

    Rob
    I agree with the FM... especially when its taken ages to develop/etch, and then drill 1000's of holes. Am really hoping the CNC will make the whole process (no pun intended) go much smoother.
    From what I've seen of youtube vids etc, not using autolevelling is a crap shoot, and if it is so simple to implement, what's the downside?

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