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CNC parallel/breakout question...macona, et al

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  • CNC parallel/breakout question...macona, et al

    I picked up a Denford MicroMill training (toy?) mill for cheap (no software, cable or dongle) and want to get it going without buying the expensive software & licenses. More details here: http://bbs.homeshopmachinist.net/sho...=SMARTSTEP%2F3

    Anyhoo, I've been talking to the nice admin fellow over on the Denford forum and it looks like my best bet is to remove the Denford auxiliary board that contains their proprietary eeprom & serial interface and connect directly to the SmartStep/3 board 96 pin header using a "normal" control program through the parallel port. I have a pinout diagram that shows the pin locations for the step & direction/etc inputs on the board. He advised me to use this device http://www.cnc4pc.com/Store/osc/prod...roducts_id=203 but cautioned me that it was only a suggestion and I should seek more experienced counsel before proceeding.

    So, does that seem like a viable plan? My budget is very tight (as usual) and I can't afford Mach 3 but I understand they have a free trial version to at least see if I can get the thing to work. I don't plan to do 3-axis contouring so is there a simpler, cheap/free program that would work? I can do DOS if nec.
    Milton

    "Accuracy is the sum total of your compensating mistakes."

    "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

  • #2
    If you also want CNC control of the spindle speed, VFD analogue etc make sure you get the BOB version that has the feature.
    If you want cheaper than Mach, which is as about as cheap as it gets, there is EMC which is free & completely open source but it may take a bit more in the way of putting together and programming.
    Max.
    Last edited by MaxHeadRoom; 09-02-2010, 01:10 PM.

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    • #3
      So, does that seem like a viable plan? My budget is very tight (as usual) and I can't afford Mach 3 but I understand they have a free trial version to at least see if I can get the thing to work. I don't plan to do 3-axis contouring so is there a simpler, cheap/free program that would work? I can do DOS if nec.
      What are the specs on the computer that you intend to use to control the mill?
      Free software for calculating bolt circles and similar: Click Here

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      • #4
        I have 3 options at the moment:

        1) Old 386 laptop which runs my DOS CNC router software; obviously I'd have to use an old DOS program with the MicroMill.

        2) Shop PC is a PIII 900, W2K

        3) Much newer Toshiba laptop with bad display recently given to me has a P4 3 gig processor, I think 1 gig ram, 60 gig drive, XP Home...will have to rig a monitor...ain't spending that much money for the display.

        ps: I don't plan on 3 axis contouring for a while, if at all.
        Milton

        "Accuracy is the sum total of your compensating mistakes."

        "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

        Comment


        • #5
          Only the laptop has enough guts to run Mach 3 but Mach 3 often doesn't run well on laptops due to issues with intergrated everything upsetting timing.

          You can run Turbo CNC which will work fine even on the 386 but TCNC has issues with circular interpolation, mainly it doesn't do more than 90 degrees so a full circle is 4 arcs strung together with slight glitches at the "corners".

          I think you would probably do best to use EMC from a live boot CD and use a pen drive for persistence of state between sessions. EMC is clunky but it works well although I haven't looked at it lately.
          Free software for calculating bolt circles and similar: Click Here

          Comment


          • #6
            Thanks Evan. I've been looking at TurboCNC mainly because it's pretty simple and I've been using ACE Converter to do dxf/g-code conversion for my router and it works well. The same fellow wrote both ACE & TurboCNC and the price is right, both hardware-wise and dollar-wise.

            Do you think that the CNC4PC device I linked to and carefully wiring it up between the laptop's parallel port and the stepper board would work or do I need some other device as well?
            Milton

            "Accuracy is the sum total of your compensating mistakes."

            "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

            Comment


            • #7
              The pIII will work for mach. Barely, but it should do it.

              I would get a board you can mount inside the machine. Something like the PMDX-122 from pmdx.com. For speed controls I like the ones from homanndesigns.com

              Comment


              • #8
                The CNC4 device you linked appears to be P.P. buffer output only, no inputs and non-isolated if I read it right.
                Depends what features you intend to implement.
                Max.

                Comment


                • #9
                  Thanks Max, I think you're right. The more I look into this, the more I'm thinking I'll be bucks and screw-around time ahead to just ditch the SmartStep board and get a HobbyCNC board kit from Dave Rigotti.

                  Someone else said exactly that on the other thread so whoever you are, go ahead & say it: "Told you so."
                  Milton

                  "Accuracy is the sum total of your compensating mistakes."

                  "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

                  Comment


                  • #10
                    The P III 900 will run Mach 3 if, and only if the OS is stripped down to the bare essentials. Absolutely all non essential services must be disabled, all eye candy must be turned off and anything that runs in the background such as antivirus software must be removed. A separate video card is a requirement. Sound and network functions should be disabled during CNC operation. All power saving and related functions must be turned off. There must be at least 512 megs ram and more is much better.

                    The board you linked to is only an output buffer. If you want isolation you will need to either build a board or spend more. Isolation isn't mandatory especially with a professionaly built machine that uses so little power in the spindle and drives. You can connect the parallel outputs and if needed for limits the inputs directly to the board without buffers. If you want a measure of protection you can connect a 5 volt zener diode across every signal line to ground.
                    Free software for calculating bolt circles and similar: Click Here

                    Comment


                    • #11
                      Originally posted by Evan
                      You can connect the parallel outputs and if needed for limits the inputs directly to the board without buffers. If you want a measure of protection you can connect a 5 volt zener diode across every signal line to ground.
                      If I try this out with an old PII 400/W98 I have stored in the attic (DOS mode with TCNC) just to see if the board works, the biggest risk would be letting the smoke out of the parallel circuit in the PC and/or the controller board if I screw up the parallel cable connections? I must be nuts, it sounds like a fun weekend's tinker session.
                      Milton

                      "Accuracy is the sum total of your compensating mistakes."

                      "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

                      Comment


                      • #12
                        Sounds perfect. Nothing to lose and you will probably end up with a working system. Don't try to run from a DOS window. Use a minimal boot disk and boot directly to DOS and run TCNC as the last line in the autoexec.bat file. If you use the "call turbocnc.exe" statement when you exit TCNC it will return to the next line and execute whatever statement is there.

                        For a custom boot disk that starts without a ram drive in 98 go here:

                        http://www.bootdisk.com/bootdisk.htm
                        Free software for calculating bolt circles and similar: Click Here

                        Comment


                        • #13
                          There used to be a site that you could download a stripped DOS7.1 this was nice for setting up a DOS boot sector with support for FAT32 and long file names etc.
                          Probably still out there somewhere.
                          I still use a motion control DOS program around a Galil card for some applications that just do not justify the Windows overhead.
                          Max.
                          Last edited by MaxHeadRoom; 09-02-2010, 08:39 PM.

                          Comment


                          • #14
                            Me again. Between family festivalries over the holiday weekend, I hope to either get this thing moving under pc control or let so much smoke out that there's no hope of using the original stuff.

                            1) Does anyone have any suggestions for where to scrounge a connector to plug onto the DIN 41612 96 way block on the board? I don't want to solder directly to the existing pins. I know I could order a proper connector from Mouser or DigiKey but since there's only 9 step/dir/gnd pins + limit switch connections I hope to find something in my stash of old PC cards, printer parts, etc to plug in neatly. I think they're 1mm round pins and any plug with the proper pin size and reasonably close pitch would work.

                            I could bash the original Denford aux board to get its connector but would rather not in case someone out there needs it later.

                            2) Are the matching step/dir/gnd connections at the PC parallel port set up in a standard configuration or are those assignments up to the individual control software's setup. I haven't d/loaded TurboCNC yet; that info may be detailed there.
                            Milton

                            "Accuracy is the sum total of your compensating mistakes."

                            "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

                            Comment


                            • #15
                              The connector is standard 0.1" spacing so you can use a wire wrap IC socket cut in half to plug in, female or male. Just trim it down to make a single row .1 spacing connector. If it is twin row recessed male pins then an IDE cable will plug in.

                              TCNC lets you configure what pins are active for what purpose.
                              Free software for calculating bolt circles and similar: Click Here

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