What's more popular, Mach3 or LinuxCNC?

Discussion in 'CNC Machines and Conversions' started by BobWarfield, Aug 2, 2012.

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  1. Jan 9, 2013 #21

    Tin Falcon

    Tin Falcon

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    Nick we do not stoop to name calling here . Friendly disccusions and civil disagreements yes. this is not a battle ground this is like discussing what brand of car is superior . Lots of subtle differences but in the end they will both get you to work and back.
    Do we need to lock the thread because of excessive head butting ?? I hope not.
    You are entitled to your opinion but need to temper your delivery a bit.
    Tin Falcon
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  2. Jan 9, 2013 #22

    MuellerNick

    MuellerNick

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    Hi Tin Falcon!

    Yes, you are right!
    It doesn't make sense to discuss with someone who made a survey that he admits is biased ("Second, the professionals are much less likely to participate.") and on the other hand is founding arguments on that survey.
    Also, ignoring arguments if they don't fit into his pattern, but repeat wrong information.
    Last but not least, someone being so familiar with all controls should be able to spell "Siemens" correctly, especially if he gets a comment about the wrong spelling, together with the right one.


    Nick
     
  3. Jan 9, 2013 #23

    RonGinger

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    As usual this 'holy war' topic has generated more heat than light. Let me make a couple facts clear.

    Mach has over 40,000 installed systems, more than half of them in commercial or industrial sites. The industrial users do not frequent these hobby forums so their presence is not well known. I'm sure none of them saw the survey that originally triggered this topic. That number is known because Mach is a business that can track its sales and customers.

    The number of EMC users is impossible to determine since it is a free download.

    Popularity is the wrong measure of any program or product. Its suitability to a need is more important. Mach has proven by nearly 10 years and thousands of users that it is a very capable program. Its popularity is a result of its suitability.

    It is clear that Mach runs accurately and reliably, regardless of its supposed weakness or difference from EMC.

    There are many ways Mach can incorporate glass scales or rotary encoders if desired. The general view is that these are not needed since a properly set up machine, running within its mechanical limits will reliably make accurate parts. If you over load a machine beyond its capability it will fail- either Mach or EMC. It does not matter what kind of feedback you have, if the machine is overloaded and the following error gets to great the part will be ruined. Dont overload your machine.

    And since Nick wants to pick on spelling he should note that the name EMC was changed, because of a legal challenge, to LinuxCNC several months ago.
     
    Last edited: Jan 9, 2013
  4. Jan 9, 2013 #24

    BobWarfield

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    ROFL, I like the heavy weight boxing analogy!

    :fan:

    We're down to "He's wrong" and "No, it's HIM that is wrong." That means it's time to call a halt, especially on this board that does such a good job of keeping things friendly.

    For everyone interested, give them both a try and ignore the zealots. There is no ONE TRUE CONTROLLER SOFTWARE.

    And yes, you can run servos on Mach3 and they'll do everything Nick claims is only possible if you close the loop back to the controller. "No, it's HIM that's wrong", LOL.

    Ron says we can get glass scales, and knowing how the interface to parallel and plug-ins work, I agree, it is possible in Mach3 though I don't think it is very straightforward, so I'm happy to leave that award to LinuxCNC along with the rigid tapping and not having to home. BTW, lots of "Pro" VMC's out there don't have those things, so I am not too worried about giving them up.

    I still have yet to find someone from the LinuxCNC camp to tell me something else that requires the loop go to the controller. I can imagine scenarios, but I want something real and documented.

    As mentioned, it's on my todos to bring up LinuxCNC again and write about it on CNCCookbook. I ran it for a while a long time ago and didn't see any particular advantages in its vanilla form. I'm no stranger to Linux and not at all afraid of it--CNCCookbook uses it to process orders and all sorts of other things.

    For those who'd like to play, Amazon has a new cheap Linux laptop I heard about. I think it is only $249. I'll have to lookup whether it can run LinuxCNC successfully or not. Meanwhile, it's one quick and easy way to see if Linux is something you can learn quickly enough to be happy with.

    Cheers,

    BW
     
  5. Jan 9, 2013 #25

    MuellerNick

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    Show me where I wrote EMC2 (it was EMC2, not EMC) and I'll stand corrected!


    Nick
     
  6. Jan 9, 2013 #26

    MuellerNick

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    So he might be implementing something completely unnecessary by your definition. Your servo system already does exactly the same. By your misunderstanding of controls.
    I gave examples for the outer loop back, I don't have to repeat them. Feel free to continue ignoring them.


    Nick
     
  7. Jan 10, 2013 #27

    BobWarfield

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    Nick, I am happy to correct YOUR misunderstanding of controls. You brought up glass scales as solving the problem of, "This simply means that the contol and the user knows exactly where the axis are. No matter how big the threshold, no matter what backlash, no matter how many steps lost, no matter wether one axis stalled due to overload."

    Those are definitely problems every CNC machine should consider, but none of them are really problems that glass scales are intended to solve with the possible exception of backlash, and even there, not so much. They simply provide a more real time input to the backplash compensation which we can set up by other means. None of these require us to close the loop back to the controller either.

    Glass scales are used to minimize problems like thermal expansion and leadscrew error. BTW, I can even tackle leadscrew error with Mach3 and glass scales. Since it has leadscrew mapping built in that is easy to use, I simply mounted a set of high quality glass scales temporarily and used them to measure my leadscrew errors. Took an afternoon and now it is done.

    Glass scales are not particularly easy to reconcile with the servo encoders the drives need either, so when you close the loop back to the controller, there are really two loops there. The glass scale provides compensation that is applied after the primary loop has been used for the gross positioning.

    Because it is only these things that glass scales matter for, as I mentioned, most commercial CNC machines including Haas and Fadal don't have glass scales by default. This is also the reason why simply closing the loop at the servo drive is sufficient--because all we need to solve the problems you did mention is to close the following error and that's what the drive does. Your outer loop examples therefore do not need an outer loop, and I have described in detail what you should have, which is what the glass scales are really for.

    But there is a reason that glass scales are so rare in the field. They simply aren't needed for most cases and there are other solutions to the problems they solve.

    Commercial VMC's without glass scales, and most don't have them, solve the leadscrew error by doing laser mapping. They are periodically re-calibrated in the field. They minimize thermal expansion errors with discrete temperature sensors.

    Machinists also play a role, they minimize thermal effects by warming up their machines and using wear offsets based on measurements taken along the way. Or by using in process probing like the RAMTIC strategy I mentioned. Isn't it interesting that a company like Renishaw is building precise probes on VMC's without glass scales? If you're clever, you can do so.

    Nick, we can keep going as long as you like. I've been doing CAD/CAM since college when I paid for my tuition by porting CAD/CAM software from DEC PDP-11's to the new generation of M68000 workstations. I know how the stuff works.

    Cheers,

    BW
     
  8. Jan 11, 2013 #28

    dman

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    you two are like children arguing over who's bike is cooler. mine has streamers and a shark fin, well mine is red and has flames. yeah well your's is stupid. well my dad can beat up your dad...


    all i see is "hey this does this and people should use it." and "well that's cool but it doesn't matter because i can get the same results mostly as long as the machine is warm and i take hours to calibrate it to begin with and there is no backlash..." clearly calibration and position mapping and predictive backlash compensation is not the same as real time closed loop dual feedback. and clearly dual feedback is not needed on a well engineered rigid mill with stepper motors and ball screws. you guys know the same things and one of you isn't taking any chances and the other is saying it's overkill. just get over it. the biggest thing i'd like to see is information on what there is to consider for control software selection and people to get over fear of "linux is hard" because it's not.


    i'm not saying to use linuxcnc, or not to. but it is something to think about, and to think about with that is that fact that stepping speed is limited by latency without external hardware. so if you have a pc in mind for your conversion linux cnc might not work especially if it's a laptop. if you decide linuxcnc is the way to go decide that before you select the hardware and read the cnc forums to pick out hardware up to the task, fast cpu's aren't the key here. it's the supporting hardware you need to worry about. you need a well tested motherboard or you may be limited in rapid rates..

    if you have a pc in mind for the controls and it doesn't have parallel or it's a laptop with poor realtime performance then an external device may be best. you'll forfeit a lot of what linuxcnc can potentially offer but that doesn't mean you wont end up with a professional quality machine.

    mach may be a great choice here but another one to consider that i didn't see in the list is rtstepper. it is a special dongle that holds the step buffers and has software that goes with it. it runs on all operating systems including mac so people with a laptop, netbook or macbook laying around, have an afinity for linux or fear windows crashes can use it. the setup literally couldn't be easier and the frontend is easy to understand.
     
  9. Jan 11, 2013 #29

    BobWarfield

    BobWarfield

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    It's classic bench racing, dman. For the gearheads out there, you can get just as much heat without light by popping up among the gearheads and asking Chevy or Ford? Big Block or Small Block?

    In the Hobby CNC world, you ask LinuxCNC or Mach3? Steppers or Servos?

    I agree, they both work. As I started out, I think you can take LinuxCNC further, but I think you can get to "hobbyist good" with Mach3 faster. I have quantified 3 advantages I see for LinuxCNC in the form of glass scales for temp comp, no need to home after crash, and rigid tapping. I've also mentioned what you'd have to do to get around each issue and how the pros handle it for those that want help deciding whether they care about those issues.

    Putting all the histrionics aside, that's pretty measured and straightforward.
    The thing I don't like is all the misconceptions out there about a lot of these issues that keep being perpetuated. In other words, all the bench racing.

    The idea that Linux is real time and Windows is not, the idea that Windows crashes so much it is a crime to ever connect it to a CNC machine, or the idea that not closing the servo loop all the way back to the control software doesn't buy you anything. Read this thread carefully to understand what's really going on each of these. Neither OS is truly Real Time, though Linux is closer. There are many fully commercial grade systems built around Windows. Both Mach3 and LinuxCNC benefit from outboard hardware for best results. Most of the benefits of servos can be had without closing the loop all the way back and there are significant advantages to running servos in either case. You don't have to take my word for it because I've documented all of it with links to reliable sources.

    BTW, for beginners, I recommend the steppers over servos simply because there is less complexity to setting up the system and they work pretty good for the kind of work the beginner needs to do. Getting ANY CNC working is leagues ahead of no CNC. For your first machine, LESS is more. You don't need glass scales and books on how to operate Linux, you just need to get a machine going. You'll love CNC once it is working. And then, once you're proficient and understand the machine's limitations, you'll find it's all upgradeable to the next level. You can even switch from Mach3 to LinuxCNC or vice versa very easily.

    But, to turn the cart back around dman, what exactly are your criteria for selecting control software?

    Cheers,

    BW
     
  10. Jan 11, 2013 #30

    dman

    dman

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    the criteria obviously varies on situations and personal preference. money, ease of setup, ease of use, existing hardware.

    if you have an existing servo machine and it is run off a tape drive, well you may not want the expense of changing over to steppers but the existing controler may not suit your needs for example.

    i will say that i haven't done a conversion yet but am carefully planning one on a manual induma mill similar to a bridgeport

    if you are asking my preference i'd say i would probably use linuxcnc on a mill, i wouldn't pay for mach, not that i don't think it's worth it but i wouldn't pay till i use something. if there is a trial period then maybe but this is part of my bias towards the open source stuff, if i hate it nothing lost nothing gained... it would not be good to purchase it and decide i hate it..

    but for a router or edm or plasma cutter i might use rt stepper. i'm not sure if rt stepper has spindle position control needed for threading/rigid taping or not, that would also determine if i'd use rt stepper on a lathe. i have the front end on my computer now and i feel it would get the job done for quick jobs, it may even be part of my initial conversion until i get money for proper hardware for linuxcnc, if i do linuxcnc i dont want to half ass it. i want fast stepping, spindle position sensing, anti backlash lead screws and just because i can, i may do glass scales, (i acknowledge that it's overkill for my needs but why not?) . i might need the extra features of linuxcnc for a mill where jobs may be more complicated. if the feature is there i'll find a use for it..

    another point of linuxcnc is that it's the only conversion software i know of that can control a hexapod. which has me thinking....

    this doesn't mean i would push linuxcnc on others. i've made that mistake with other technology. it's never i good idea to open people up to something i appreciate as far as computers. they always blame you when things don't work.

    reasons i use linux are that i don't agree with the microsoft 1 license per person per hardware. if you are licensed to use it i don't know why you can't migrate it to a new system?... i'd rather be an open source user than a pirate, software is way to profitable to make these restrictions. it takes nothing to reproduce so you are only limited by your ability to distribute once the work is done. i get people need to get paid for work but the microsoft model is absurd. i will say windows is more stable than people give it credit for. especially windows 7.
     
  11. Jan 12, 2013 #31

    ninefinger

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    It shouldn't be a question of LinuxCNC vrs Mach, you need to do your requirements definition and then go from there. Do you NEED to close the loop in the motion planner? Do you need the advanced features that LinuxCNC can offer (at the expense of investing time and possibly hardware resources)? If your retrofitting a large CNC with servo drives (and velocity feedback) then LinuxCNC probably makes good sense as it can be configured to work with the existing drives with the addition of a relatively inexpensive hardware card (ie MESA). If your building a home hobby mill / router etc with step controlled stepper or servo drives then either one will do.

    I personally use LinuxCNC. I admit I did find it hard to get started (begining in Feb 2010) mostly from a PC compatibility point of view and just jumping in without doing my homework on what works / doesn't work with Linux / Ubuntu. Once I figured out that my assumptions were not true (ie Linux could run well on ANY older PC) and I got PC hardware that was known to work I was off to the races. ( I enjoy a challenge and converting to CNC has given me many to work through!)
    Anyways here is how I see things:

    Pros for the LinuxCNC is the 2x free - free operating system and free software. Can do rigid tapping, close the loop in the motion planner if needed, can control almost any servo / stepper drive system (may require additional hardware).
    Cons are that to many Linux is yet another item to learn while jumping into CNC (but not that bad.) Can be picky for PC hardware. Not as large a user base.

    Pros for Mach are large user base - there is commercial support for it and even commercial "screens" to customize the look - This can be done in LinuxCNC but don't ask me how, seems to require a bit of programming knowledge.
    Cons are requires license of Windows and license of Mach. Can't do rigid tapping, limited to controlling step/dir based drives.
    Not to sure about lathe work - I'm in the early stages of making a small cnc lathe and plan on using Linuxcnc for it - simply because I have it already on a pc ready to go.

    Mike
     
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  12. Jan 13, 2013 #32

    MuellerNick

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    Please stop repeating that nonsense!
    The Haas has an outer control loop. I already said that. Look at the manual mode of the TL-series lathes to understand that. I said that -I think- the third time now.

    You do not understand what an outer control loop does.
    I one looks at a servo-system where the inner loop is commanded by a speed signal and the feedback to the inner loop is by a tach-generator, things should become quite obvious what an inner loop can do, and what an outer loop must do.

    And AGAIN! The outer loop is -for example- necessary for threading. No, not rigid taping, but already single point threading on a lathe. As soon as the tool starts to cut, the spindle RPM will drop. This can only be handled by an outer control loop properly. It is called a coupled axis. The feed of the Z-axis will adjust to the spindle RPM.
    Hobbyists will insist on thinking one pulse per revolution is enough. It ain't.


    Nick
     
  13. Jan 14, 2013 #33

    RonGinger

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    Sorry Nick, you are again spreading nonsense. Mach uses a single index pulse and there are thousands of users making perfectly good threads with it. If your spindle motor slows down enough to cause a problem when you start cutting you are taking to big a cut. I am talking about slowing enough to cause a problem, yes, I know there is a small change with load, but its not enough to cause a problem in a properly designed lathe.

    You just wont let it die will you? You are fighting a lost battle- Mach works, and works well and over 40,000 systems are installed and making parts every day, both hobby and commercial.

    I think this topic has gone just about far enough. There has been little new, useful info in the past several replies.
     
  14. Jan 14, 2013 #34

    Tonnetto

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    I've been a machinist for 20+ years, the early CNC machines I've worked on had propriatary controls with serial port program transfers. An Okuma LB15 lathe and a Mazak Quickturn 15. Moving ahead a few years, we stuck with Mazak and sold the Okuma. Mazak changed the control to work out of Windows 95 (Obviously with external hardware) and the machines ran fine. A few years later they stepped up to Windows XP, they still run great. I don't know how many of you are familiar with Mazak, but it's a huge machine manufacturer that started in Japan, just give them a look at their website. My point is that it's the machine and the interface that makes it good, not the operating system.
     
  15. Jan 14, 2013 #35

    MuellerNick

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    And in the next sentence, you admit that Mach can't handle deep cuts.
    Sorry, but you have to understnd the principles of things, before you can discuss about them.
    That discussion is no longer about Mach vs. LinuxCNC, it is about what a outer loop is used for. BW insists, that a outer loop is not necessary. But threading IS an example for an outer loop that even Mach uses (in a primitive implementation).
    As long as you don't understand this simple principle, the nonsense in this thread will continue.

    I'm out of here, arguments don't count. Hobbyists forums are not the right place to discuss more complex things that are beyond toggling a switch.

    So dream on, be happy and tell false information to eveyone who is dumb enough to believe.

    Nick
     
  16. Jan 14, 2013 #36

    artag

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    Although there are commercial machine controllers that run Windows, it's not necessarily unadorned. As well as closing the position loops in external servo controllers, some use an RTOS that runs Windows at a lower priority, just like realtime Linux. One such is IntervalZero - and this is also used to support soft PLCs such as Siemen's. However, it's not cheap and can require multiple licences to run both a soft PLC and a machine controller at the same time.

    intervalzero
    .com/assets/wp_softControl.pdf
     
  17. Jan 15, 2013 #37

    Tin Falcon

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    Name calling not allowed here!!!!
    and to accuse a Representative of MACH or any other vendor of spreading falsehood bold to say the least. Nick if you want to stay here you had better grow up.
    I an locking this thread.
    Tin
     
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