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  • #31
    Machs ability to allow modifying screens easily is a very nice feature indeed. That was one of the reasons I did not go to linuxcnc after looking it over. When I started using Mach for a lathe, and several attempts at getting numerous bugs fixed is when I re-looked at linuxcnc. Having used Mach for several years and now actually test driving linuxcnc, I came to some conclusions.

    In general, mach seems to be designed to be driven from the screen via a mouse. I think that is why the ability to modify the screenset is so popular. Yes you can add external controls or a full control panel but you can run into a lot of headaches there interfacing everything. I also believe the vast majority of machs users are hobby type users with very simple machines, most often bench top machines. Yes, mach has been used to drive more complex commercial machinery but that is the rare exception. I looked hard for examples when I retrofitted my 14x40 lathe, almost nothing similar out there, everything was 9x20 and 7x machines for the most part.

    When I looked harder and test drove linuxcnc, the difference in the user interface finally hit me. Linuxcnc was designed and intended to be driven by hardware buttons and such with a real control panel, just like commercial cnc machines have. You can drive linuxcnc from the screen with a mouse without any problem but it is nothing like mach in that respect. It is true that the screensets cannot be modified unless your very proficient in linux programming. There are add-on screen/windows that can be used for many purposes that are not that difficult which makes up for that lack of ability to edit the main screens.

    Lets compare to high end commercial machines, the likes of haas / mazak/ okuma/ fanuc controls and such. Do those machines allow you to modify their screensets? Why did those manufacturers not feel that was important enough to implement? All of the big league commercial machines have buttons/knobs on the panel for jogging/cycle start/ estop/ feed and spindle override/ feedhold and such. The machine is controlled mostly from the control panel. Linuxcnc is commonly used to retrofit older versions of these type commercial machines and interfacing to those machines is quite easy, toolchangers and all. Mach is just not aimed at this market and is very limited in its ability to interface to all the different hardware requirements requiring the use of boards from multiple vendors that don't play nicely together.

    For interfacing to the outside world in linuxcnc, MESA electronics boards are very popular and for good reason. They have boards to meet just about any interface requirements imaginable, bug free, with fantastic support. I would call them nearly plug and play. A good example would be the boards I used for my newest lathe conversion (same boards would be excellent for a bridgeport or vmc). I got the mesa 5i25/7i77 combo. The 5i25 is a pci slot board that goes into the host computer, it uses a parallel port type cable to interface to the external 7i77 board. The 7i77 board has screw terminals for 6 servos, 6 encoders, 48 I/O lines, spindle or vfd outputs, high speed rs422 port for expansion. The outputs handle 300ma each directly, will directly handle 24 volts or more and are overcurrent protected and more. The board combo costs under $300. With mach, you would need a smoothstepper, a couple of breakout boards, a bunch of solid state relays to handle the 24 volt stuff, maybe a few more boards to get everything interfaced and would spend a lot more money in the process. Pete, the owner of Mesa electronics is online daily on the forums and only a phone call away if you have any problems, that type of support is totally non existant for mach aftermarket boards. Don't forget, I have a mach setup with smootherstepper and break out boards so I am painfully aware of the support differences. How many years did it take for the smoothstepper to support backlash compensation and then not fully? Oh yea, I used my contour shuttle with linuxcnc just like I did with mach, and used a cheap $5 usb game controller which I gutted for my feed and spindle override pots along with 13 more buttons in addition to the mesa board I/0. My newest lathe homes to the index pulse from the servo encoder, and I used the original servo drives with their 10V analog control lines, try that with mach!

    Yes, you can setup cool looking screens in mach, but if your interest lies more in a highly accurate dead reliable machine with abilities mach could only dream of, and without the endless bugs, the the choice is clear.

    Comment


    • #32
      One correction sparky.. The 5i25+7i77 kit that comes with the interconnect cable is $239

      I too love the mesa hardware. My conversion which was done a couple of years ago uses 2 5i20 pci boards + 7i33 + 7i48. For $568 at the time and some opto22 boards from ebay I have 10 analog outputs (+/-10v), 10 encoder interfaces (ttl or differential) and 96 digital i/o. I have used them all. (and they are all controlled in realtime) And to show you how flexible linuxcnc is - I am using amc servo amps setup in velocity mode. Originally the servos had tachs on them. Well the tachs started failing and so instead of re-configuring the amps - I took the virtual velocity estimate from the mesa encoder - hooked it back out through the mesa +/-10 volt mesa output and back to the amc amp. Poof - virtual tach. this was all done within linuxcnc hal files. No programming.

      mesa has a lot more options out there now. I plan on using the 5i25 for the lathe retrofit we are planning. (old cincinati malicron)

      Peter from mesa is on the linuxcnc message board (he even posts on cnczone often), Irc and the mailing list. He is always there to answer questions.

      sam
      Last edited by skunkworks; 09-18-2012, 08:49 AM.

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      • #33
        My 2 cents, for what it's worth.

        Bought one of those cheapie cnc routers off ebay. Both problems I had seting up EMC were hardware related. EMC is very peticular about latency. For proper timing of the steppers, it wants the processor's undivided attention. If the processor has to take time to mess with the video card or other features on the mother board, it won't pass the latency test. I wound up getting my mom's old machine (7 years old?) and it passed the test fine. It didn't like my new Dell.

        Second problem is that the parallel ports in newer cards don't use the same port numbers as the old ones. Once I got that figured out, it ran fine.
        Definition: Racecar - a device that turns money into noise.

        Comment


        • #34
          One OT comment and one not so much.

          1) Roared home last night with my shiny new LinuxCNC CD and stuck it in the shop PC to try it out. Could NOT get the thing to boot from the CD and couldn't get into the bios to change the boot sequence. Tried for almost an hour with different key inputs at different times during the bootup process and never got it to work. Gave up and went back to working on the lathe toolholder plate.

          Woke up this morning with a major league dope slap: Wireless keyboard on the shop PC, has to be in Windows to work....idiot! Good example of my level of computer savvy. Pilfered a wired K/board at work this morning and will try again tonight.

          2) Went on the Linux forum this morning and sniffed around a bit. SMART fellows abound there! Prolly way too smart for me but I did run across a post by BigJohnT where he took a guy's mach .xml file and converted it an EMC configuration file to help him get up & running. What a prince of a guy!
          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

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          • #35
            BigjohnT is one heck of a nice guy.

            Couple of things. When you burn the iso - make sure you burn it correctly. You doin't just burn the ISO file to the disk - you have to have burning software that takes the ISO image and burns the image to the disk.

            http://www.linuxcnc.org/docs/EMC2_Getting_Started.pdf

            There are 2 currently supported livecd's - one based on ubuntu 8.04 and one based on 10.04. Both allow you to update to the latest version of linuxcnc (currently 2.5.1). 8.04 will have less problems with older hardware.

            http://www.linuxcnc.org/index.php/en...d/21?task=view

            Originally posted by DICKEYBIRD View Post
            One OT comment and one not so much.

            1) Roared home last night with my shiny new LinuxCNC CD and stuck it in the shop PC to try it out. Could NOT get the thing to boot from the CD and couldn't get into the bios to change the boot sequence. Tried for almost an hour with different key inputs at different times during the bootup process and never got it to work. Gave up and went back to working on the lathe toolholder plate.

            Woke up this morning with a major league dope slap: Wireless keyboard on the shop PC, has to be in Windows to work....idiot! Good example of my level of computer savvy. Pilfered a wired K/board at work this morning and will try again tonight.

            2) Went on the Linux forum this morning and sniffed around a bit. SMART fellows abound there! Prolly way too smart for me but I did run across a post by BigJohnT where he took a guy's mach .xml file and converted it an EMC configuration file to help him get up & running. What a prince of a guy!

            Comment


            • #36
              Originally posted by skunkworks View Post
              BigjohnT is one heck of a nice guy.

              Couple of things. When you burn the iso - make sure you burn it correctly. You doin't just burn the ISO file to the disk - you have to have burning software that takes the ISO image and burns the image to the disk.

              http://www.linuxcnc.org/docs/EMC2_Getting_Started.pdf

              There are 2 currently supported livecd's - one based on ubuntu 8.04 and one based on 10.04. Both allow you to update to the latest version of linuxcnc (currently 2.5.1). 8.04 will have less problems with older hardware.

              http://www.linuxcnc.org/index.php/en...d/21?task=view
              Amazingly, I at least got the .iso burn completed properly. I stuck it in another (old) PC last night and it loaded up fine. The latency test on that box was mid 15K's...is that OK?

              I'll ck. which version I got tonight as I'm not sure which one it is.

              Thanks for the info!
              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


              • #37
                That is a pretty normal latency. Some computers can get sub 10k. Depending on how the rest of the computer performs and what your driver timings are - you should be able to get step speeds from 30 to 40khz. YMMV

                One thing to look at - it seems that disabling hyperthreading in the bios helps latency.

                sam

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                • #38
                  Mid 15's latency is great, few computers can do better. The latency number mostly has to do with how fast it is going to be able to put out pulses to your motors, higher latency means slower max speeds. At 15K latency you will be able to run steppers faster than the motors are capable.

                  Just a FYI If someone uses mesa boards for their interface, the latency importance is greatly reduced. That is because the mesa board handles the pulse generation onboard. Same concept as the smoothstepper with mach.

                  Also, I referred to the 7i77 mesa board which is used with servo systems. There is its brother, the 7i76 which is intended for stepper systems or servos using step/dir control. It also handles 6 axis, 48 I/O lines, full control over the spindle and such. It is also cheaper yet. Also, linuxcnc has a full interface for parallel port interfacing, like mach3 does which may be all a person requires.

                  The 5i25 pci board in the computer can run 2 daugher boards directly, so simply adding a second 7i77 or 7i76 board doubles your hardware interface abilities, ie 12 servo axis, 12 encoders, 96 I/O lines, 2 spindles and so on. The 7i76 alone is about $160. Or, you can mix and match with daughter boards for endless combinations. If your computer has a parallel port then those pins are all available as well for use as is usb devices for jogging and pendants.

                  BigJohnT on the linuxcnc forum is a fantastic guy, he helps everyone out and constantly contributes his work. He wrote a whole load of wizards for lathe which are fantastic and on his website for download.
                  Last edited by Sparky_NY; 09-18-2012, 02:02 PM.

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                  • #39
                    Also to add.... The 5i25 without the daughter boards (and it only cost $89) acts like a dual printer port. IE - you could use your existing bob but you get high speed everything. (stepgen-pwm-encoder counting-i/o)

                    http://mesanet.com/fpgacardinfo.html

                    sam

                    Comment


                    • #40
                      Hi Guys,

                      Just a bit of trivia on the LinuxCNC manuals... I started working on improving the manuals all those years ago because I was confused and could not find anything and I was a rank Linux NewBee so it was very difficult for me to make sense of anything. With some help from the core developers on building manuals and other behind the scenes stuff I started to translate from "programmer speak" to redneck what the heck is a Linux language. If you have not looked at the manuals in a few years I hope your surprised when you look again.

                      Enjoy
                      John
                      Last edited by BigJohnT; 09-18-2012, 06:25 PM.
                      My Web Site

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                      • #41
                        BigJohn,
                        Allow me to be one of the first to welcome you aboard, your knowledge precedes you and I'm sure you will bring a lot of information here.
                        To help us along can you provide some links please to the manuals ?
                        .

                        Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



                        Comment


                        • #42
                          John,

                          Thanks for the welcome aboard. All the docs including the man pages for all the components is on this page. Man pages for you non-Linux folks are short for Manual Pages. I assume before fancy desktops and GUI's the only source for info in unix/linux was the man pages. The interesting part is you had to know the name of the program to view the man page from the terminal.

                          John
                          My Web Site

                          Comment


                          • #43
                            BigJohnT:

                            Welcome to the forum.

                            Just bought an Enco mill with a cnc masters supra retro fit kit partially installed. The BS are partially installed. At this point I have many more questions than I thought possible.

                            I know very little about machining, and nothing about CNC except that I wanted to learn more about it. I got a copy of Gibbs Cam with the mill and kit. I like what I've read about Linuxcnc. My question is, as a complete newb how steep is the learning curve for any cnc software compared to linuxcnc? I took a brief look at the link you provided, some of it made sense, and some of it still wasn't "redneck" enough for me.

                            Anyone else feel free to chime in.

                            Didn't mean to hijack the thread, but seemed it was about CNC programs.

                            thanks,
                            Ken

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                            • #44
                              WoW...
                              A high wind a rain storm in NL brings out the best...thanks guys !
                              e2die
                              please visit my webpage:
                              http://motorworks88.webs.com/

                              Comment


                              • #45
                                Ken,

                                Thanks for the welcome. Well if you take it one bite at a time it is not too hard. If you know little I would recommend reading my G code tutorial. It is specific to LinuxCNC but the general concept is the same for most controls. For LinuxCNC and questions about installing LinuxCNC you will get a lot more exposure on the LinuxCNC forum.

                                Is your kit steppers or servos?

                                John
                                My Web Site

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