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Thread: Use a robotic arm instead of building cnc mill?

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    Default Use a robotic arm instead of building cnc mill?

    I may soon have the opportunity to purchase an ABB IRB3000 6-axis robotic arm REAL cheap, much cheaper than building a quality cnc mill. My question is can a router be mounted on something like this and be used to create anything that I would on a cnc machine? Repeatabilty is .002". Is this accurate enough? Is this worth trying or a waste of time and money? I think the programming could be a catch, because there isnt much aftermarket software for these. Are there other reason that a robotic arm isnt used instead of a cnc machine?

    Thanks all.

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    Last edited by SCCoupe; 10-13-2005 at 10:20 AM.


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    I have too thought about the same thing and it would be really cool but nearly impossible to program, you also have a rigidity issue to watch out for.
    I know you can program them to do straight lines, but I am sure its not easy.
    If a straight line is hard, think about what it would take to program an arc keeping the router at the same height.

    Jon

    CNC Mini Lathe Plans and Rotary Table kits:
    http://jfettigmachines.com


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    A customized step+dir to degrees converter wouldn't be impossible to implement on a microcontroller. A hardware dongle to the paralell port would be neat



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    Actually the programming wouldnt be any harder than writing g-code with notepad. The controller for these arms take car of the rest for you. Its basically plotting points and the robot goes there. If you want an arc, then you give it 3 points and tell it to arc. You dont have to give commands for all 6 axis to move it, the controller takes care of that stuff for you. Not that Im saying that the programming would be EASY. However with a 6.5' reach, it has it possibilities i tend to think.



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    I say go for it,
    I own 2 small IRB's (seiko)and can do light engraving, light drilling no problem with them. (things like pcb's, wood letters, ect..) My problem is they are 1980's technology, and the programing has to be done soley by this ancient software it uses which requires manual point data input via keyboard. Ie.
    X=100.00,Y=102.00,Z=30
    this is for every point needed and is too time consuming,
    I create drawings in cad, plot the X,Y,Z, and use a small macro program to collect all the xyz data from cad into a spreadsheet like chart, and then I type away into my controller.

    But because your robot is much newer,and A ABB system, you will find it easy to do point to point programming, it's as simple as jog the robot to the point and press enter,move to next point and press enter and All data is loaded for you.
    I have been on alot fanuc and ABB trainning courses and seen their equipment doing amazing things for the auto sector. I guess the big question is do they have a way of interpolating cad files or text files? my guess would be yes.

    My experience is that robots are great for repetative tasks, so if you want to pound out the same part definetly worth it, but if you want to constantly change programms I would look into seeing if they sell a cad/text editor type software package.

    Rigidity is not great on small robots, but the bigger you go the better they could handle loads and inertia, however,I dont think you could mill with the robot on a constant basis, you would be constantly working against the servo's and brakes and that could cause early wear and failure in my opinion.

    But I still say go for it....and good luck

    menomana


  6. #6

    Cool Robots rock -- go for it.

    As one of the previous posters mentioned, as long as the controller is included, you shouldn't have to do anything too complicated to get the motions out of the system that you want. I would go ahead and call ABB applications support and ask them what sorts of GCode packages, etc. are available for the model controller that comes with the robot you are looking to purchase. A lot of these articulated robots are used for painting and welding (as opposed to pick and place), so most inherently include some "tool path" programming capability.

    As for the rigidity of the system, I think you'll be surprised how beefy they are. The IRB 3000 can carry 30kg, which is a lot of weight. You shouldn't be pushing with anywhere near this amount of force while routing, so I wouldn't worry about the servo motors wearing prematurely. Furthermore, some of the ABB's are washdown capable, so this may be great for a dusty environment.

    Final word is I think this will work for you, but I would find out as much as you can about the system you'll potentially be buying. Make sure it works, as spares for these robots can be murderously expensive. Find out what controls it has, and then call and talk to an applications engineer. They'll be the best people to tell you whether or not the system can do what you want it to do.



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    Just a word of warning...
    Some of those beasts are VERY fast and if they goes bananas, tools or no tools adapted...
    Better stay out of reach.
    /jan



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    I have used ABB robots in the past and I have even worked for a robotic manufacturer.

    I will tell you that ABB is a good robot generally, they are known for repeatability. They like many robots are programmed in a Cartesian coordinate system (xyz). X and Y are backwards of CNC. They do not use g-code. They have a proprietary language called Rapid. MOVL = straight line, MOVC= Circular or arc motion, MOVS= spline motion.
    I have set up robots to do what you are trying; the application is generally referred to as material removal in the robotics arena.

    I do not know if ABB has a G-code translator, but if they do it will likely cost thousands if not 10’s of thousands. They charge a lot of money for stuff. I once asked for a serial communications port for an earlier unit that had only a floppy drive. They wanted $20k to do it. The unit already has serial capability but for them to unleash it they wanted enough to retire on.

    Most people confuse accuracy with repeatability. You are probably referring to repeatability. The accuracy of robots like this are always contingent on how accurate your particular physical robot was manufactured, the calibration of the arm and how well your tool is defined. These three elements are in addition to the other aspects such as mechanical drive wear and servo/resolver resolution. Additionally arm deflection and motor accel / decel values add challenges to high speed work.

    You can start with a new factory calibrated arm, with no wear or damage and a laser calibrated end of arm tool and possibly produce reasonably good large parts, but due the gangly nature of robots such as this they are not usually capable of applying force and maintaining accuracy at any kind of speed, at least not over large areas.

    In plain terms, you can process parts, but not very accurately and plan on using point to point programming unless you wish to pay big bucks to ABB or you can find a third party software package.



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    Quote Originally Posted by RGeo View Post
    but due the gangly nature of robots such as this they are not usually capable of applying force and maintaining accuracy at any kind of speed, at least not over large areas.

    In plain terms, you can process parts, but not very accurately
    Thatīs my experience too. I regulary work with ABB IRB 5400/580-series, they too are strong, but not with accuracy at the same time.

    A No Go if rigidity and accuracy is a concern, especially when involving rotating tools.

    But six axis would be nice.



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    if you say you can get it cheap go for it. spares may be expensive but its still a good idea. so long as you can get the programming figured out...

    i dont know sqat!!! will be asking dumb questions


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    I saw I robot arm on ebay that the guy had been using to run a plasma cutter.

    The programming looks like a fun task, but hell they are using these things with a router to trim thermoformed plastic sheets for door trim and with lasers to trim fabrics.

    So yeah it's doable and I am jealous if you are getting a sweet deal, because I have been waiting for one to appear in my price range.

    I'll be teaching mine to weld, when it finally happens.

    Dan

    P.S.



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