Posts by dodkipod

    KR210 is quite large and rated for 210kg payloads. are you sure you need such high payload to mount laser head? yes, KSS is "Kuka System Software" which is software installed on Kuka controller. About your questions on accuracy.... why don't you define it? don't you know what is tolerable for your application and what is the size of working area? what is your "close enough"?

    I am sure that we don't need such a high payload, but the small payload robots are short in reach. The kr210 is just easily available to us, that's all. It could also be a different robot with a similar reach for all intents and purposes.

    Its hard to define what's tolerable to us and what isn't. "Close enough" basically means that it looks close enough. The 2d applications are meant to allow us to cut metals ourselves instead of outsourcing like we do currently. If I need to cut a circle and rectangle in order to later weld them together (manually) into a lighting fixture then close enough means that it looks like a circle and will pass as a circle when looked at. If I want to cut an odd shape in order to create an "installation solution" (sorry, don't know the term in English) that will later be part of existing infrastructure in, say, a new event hall - it just needs to have the holes be more or less the correct size and shape so that the metal workers can fit and weld it into place (we will late hang lighting/speakers from this "installation solution".

    The 3d applications will basically be cutting holes into existing products. Things that are too large for a regular laser cutting machine, or have angles. Possibly cutting decorative features into existing products as well. So say I need to cut a hole into a metal tables legs to later fit a pipe through and weld it together - I just need the holes to be "close enough" to size and shape. If the hole will be completely elliptical then yea, that's no good, but if its pretty much a circle then its fine. I can cut a slightly larger hole to compensate for inaccuracy in cases like this. If I want to cut wavy lines into a metal lamp shade as decoration - practically no precision is required.

    Does this make sense? I tried to define it as best I could.

    The backlash issue is hard to quantify. Unlike a CNC machine, where each axis's backlash is purely one-dimensional, the serial kinematics of a robot arm mean that each joint's backlash multiplies into each axis "downstram" -- the error becomes more exponential than linear.

    To complicate matters, the backlash of each axis can have very different effects depending on where the robot is in its operating envelope. Take Axis 2 -- it's backlash can "flip" depending on whether the A2-A3 link is forward of vertical (gravity pulling it fowards) or "leaning back", where gravity will act in the opposite direction. Plus the counterbalance unit adds another variable into the mix.

    There are techniques to minimize the effects. For example, for 2D cutting, keep the end effector orientation fixed at all times, and keep the arm in a pose where gravity effects don't change. Try to avoid cuts where any axis reverses direction mid-cut, and use "run in/out" motions to ramp into each cut when a directional change is required.

    Sorry but English is my second language and though it's pretty good, I don't know many of the technical terms. "run in/out" = lead in/out? The "extra pathing" added to the beginning and ending of cutting paths? If so, are you suggesting that we use this for every new direction and not only for the start - end?

    I'm particularly interested in what you said about avoiding reversing direction mid cut. This sounds like great advice - thank you. So say when cutting circles, maybe divide the cut into 4 and have a lead in+out for each of them so as to minimize the effect of reversing the direction of the axes? The bumps this will create are not an issue - we can grind them away with an angle grinder. Does this sound reasonable to you?

    Thank you for your reply. We are indeed looking at a kr210 with a krc4 controller. If we choose to go with a different manufacturer we will make sure to get the most recent controller possible.

    The robot we are looking at is refurbished and should be in good enough condition. Could you elaborate on the backlash issue a little? I know we wont be able to cut a perfect circle, but I was under the impression it would at least be close. We don't need utmost precision, but if the issue is extreme then it will be a problem... Its this reason why I am trying to figure out what type of robot would be best. Any advise on this will be greatly appreciated.

    I am particularly interested in what you said about cad/cam support. We intend on using sprutcam for this, do you know anything about this program? Also, kss is the kuka software installed on the controller - correct?

    Thank you again for your help.

    Hello again , I posted on this forum last year and received invaluable information. A lot has happened since and I would like to ask for your help again.

    I represent a company currently occupied in sound and light. We manufacture, fabricate and customize lamps, lighting fixtures and installation solutions.

    We are looking to automate our processes and will soon be purchasing a robotic milling cell (purchased as an all inclusive standardized cell from the vendor). In addition to this, we also want to create a (fiber) laser cutting cell as we didn't find any standardized cells that suited us. The cell will be used both for cutting sheet metals (2d cuts) and for cutting into existing products such as a pre-assembled lighting fixture (3d cuts).

    The laser system will be comprised of an IPG source and chiller and a raytools cutting head, we will probably add a rotating table of some sort as well. The gas compressor and fume extraction parts will be sourced locally. The parts will be integrated by the same integration team that will assemble the milling cell. We are in touch with our local authorities in order to understand and comply with the safety standards.

    The two main questions I have are the following:

    1. We will probably use Sprutcam as the offline programing software for the milling cell. Will it be able to handle the laser cutting too?

    2. How do I choose the correct robot for the laser cutting cell? The robot will be used/refurbished, so purchasing a customized extra precise model is not an option. This is ok as we do not require high accuracy/precision, but we still want to be as accurate and efficient as possible within our limitations. Looking at the robots used in other laser cutting cells I saw many different options such as ABB irb 1410/2600/4400, fanuc 20iB and many many more. We would prefer using a kuka model, but we are relatively flexible with this. The point is, different companies present the specifications for their products differently, making it harder for me to compare between them. Do you guys have any advice as to what I should look for in choosing the correct model other than repeatability and reach? The cutting head only weighs a few kilos but I also know the higher the load capabilities of the robot - the sturdier and more able to absorb vibrations it is, should I get a high payload robot? Should I be looking at the rotation range and speed of the axes? Are differences between models that great? The most available robot to us is the kuka kr210/240. Would this be alright do you think?

    Thank you very much

    1) The code came is 3 .src files (and 3 .dat files which I was unable to open), the first one looks like this ("another one" is the name I gave to this specific test):







    BAS (#INITMOV,0 )



    ;Make your modifications here



    ; Generated by AUTODESK Fusion 360 CAM 2.0.8560

    ; Creation date: Wednesday, June 24, 2020 14:56:06

    ; Set PTP velocity and acceleration

    $VEL_AXIS[1] = 25

    $VEL_AXIS[2] = 25

    $VEL_AXIS[3] = 25

    $VEL_AXIS[4] = 25

    $VEL_AXIS[5] = 25

    $VEL_AXIS[6] = 25

    $ACC_AXIS[1] = 20

    $ACC_AXIS[2] = 20

    $ACC_AXIS[3] = 20

    $ACC_AXIS[4] = 20

    $ACC_AXIS[5] = 20

    $ACC_AXIS[6] = 20

    ; To set 'Tool On Robot' Mode


    ; Set smoothing value

    $APO.CDIS = 2

    ; Set $ADVANCE value (number of points read in advance)

    $ADVANCE = 3

    ; Set BASE

    $BASE = BASE_DATA[1]

    ; Load Tool


    ; Set Tool


    $TOOL = TOOL_DATA[3]

    ; Spindle ON/speed




    ; Spindle OFF



    and here is a shortened version of one of the other two (they are similar):


    DEF sTrace1()

    ; Generated by AUTODESK Fusion 360 CAM 2.0.8560

    ; Creation date: Wednesday, June 24, 2020 14:56:06

    ;FOLD sTrace1

    ; Start position (joint) = {A1 5,A2 -80,A2 -80,A3 100,A4 75,A5 -60,A6 -65}

    ; Tool Number = 3

    ; Spindle Speed = 11999 RPM

    ; Program file name = sTrace1.src

    PTP {A1 5,A2 -80,A3 100,A4 75,A5 -60,A6 -65,E1 0,E2 0,E3 0,E4 0,E5 0,E6 0}


    LIN {X -85.000,Y 0.000,Z 15.000,A -150.000,B 0.000,C 180.000} C_DIS

    ..another 200 lines that look like the one above (I'm assuming these lines are the cutting path broken down into points)...


    2) The more I learn about all this the more I realize how far out of my depth I am XD

    What do you mean by network type? Forgive this silly question, but from the products I'm used to (sound and light), different controllers are just connected by an ethernet cable, is this what you mean?

    Either way, assuming they are connected physically and compatible in theory. You're saying there would be some programming to be done in order to turn theory into practice? Is there anyway to avoid writing code myself? like, an online library or something standard that the vendors of the e.o.a.t or robots might provide?

    Lets say I purchase like a package deal from a big used robots vendor that includes the bot, paraphernalia and a spindle tool. Life should be relatively easy for me. I would program a path in fusion 360 (assuming I don't use the feature described above in the "1)", this would give me g-code right?), move it over to robodk/sprutcam/similar that would translate the the g-code using the correct post processor according to the selected robot model and give me the code meant for the robots controller and bobs your uncle right? Or am I wrong? (I'm assuming I'm wrong somehow)

    But after that, I would want to purchase a different e.o.a.t that would have its own controller. Assuming I would want to integrate it into the system myself I would have to know how to make the right electrical + network connections in the i/o (assuming ill have any available and that they are compatible). And then what do I do?

    Thanks for that, that was very helpful of you =]

    Some more questions if I may:

    1. I found a bunch of post processors for fusion 360 for various robot manufacturers (kuka, yaskawa etc.). I played around a little and was able to get a bunch of code by posting using one of these post processors (a simple circular cutting pass). Is this the code for the robot? Could I give this code directly to the robot, thereby bypassing the need for a program such as robodk or sprutcam? I don't actually mean to do this, I'm just trying to understand.

    2. Could I get a general explanation about integrting all the different controllers? What I mean is, the robot itself has a controller, the e.o.a.t will have a controller, the rotating table and automatic tool changer need to be controlled somehow as well. I don't expect to get a full guide here, just like a general explanation about the order of operations so to speak. Am I correct in assuming all controllers will be linked somehow to the robots controller and will be given instructions from there? The code generated by whatever post processor I end up using, I need to make sure it includes instruction for the e.o.a.t and paraphernalia right?

    Robots are made from parts..thise parts have tolerances. As long as tolerances are within some limits, those are good parts and can be used to make robots. But this means that every robot made will be slightly different and not perfect match for model used in software...

    This was extremely helpful, thank you so much

    I'm afraid we can't afford it, but it seems to me like its not completely necessary.

    In my experience, a 10:1 ratio between accuracy and repeatbility has been a decent general rule of thumb. This assumes no steps have been taken to improve accuracy.

    So as a general rule of thumb, if I get a robot with +/- 0.06mm repeatability, its accuracy would be roughly +/- 0.6mm? This still seems pretty good to me

    Ok so I think I understand. If my robots repeatability is +/- 0.06mm then it can perform the same task, each iteration being within 0.06mm to the last one. If the robot is inaccurate, the path it makes may differ from the path I asked it to make, but in every iteration, it will make the "same" mistake right? So basically, with low accuracy, mistakes will be made. However, the "same" mistake will be made every time, within 0.06mm.

    In order to improve accuracy, I can run some tests, sending the robot tooltip to a certain point and seeing how close it gets, thereby learning the range of error and then incorporate the error into the path I program. So say I set it to move to x/y/z and I see that it ends up in x-1/y+2/z-2, I can take these things into account when programming, making the end result more accurate (within 0.06mm every iteration). Did I get that right?

    Can you guys give me a gross estimate of the range of inaccuracy? We're not going to do any precision milling, its (at least at this moment) looking like we will be using the robot for foam/wood milling, making sculptures and designs for show-business, hotels and the likes. Were not looking for pin point precision.

    Edit: bad manners asking questions before researching, I know, I do apologize. From what I can tell the accuracy is something like +/- 1mm, does that sound about right? How much worse does this get when milling harder materials such as wood?

    they use positionally accurate robots (HA or ABS variants)

    Can you elaborate on this a tiny bit please? All the milling videos I have seen use "regular" robots, for example KUKA kr180, but when I search for positionally accurate robots I do find specific models.

    Thank you all for the great responses.

    One question about accuracy though, granted, we don't need anything super accurate and I'm sure we will be fine. But out of curiosity, if bots accuracy is such a thing, how is it that they can create such impressive sculptures such as these (image from a google search): digital-stone-carving-robot.jpg

    Ive seen many videos on instagram of robots milling/sculpting in foam with a large spindle on a large robot. From reading the responses in this thread I would assume these should be very inaccurate, yet the end result looks great.

    Thank you for the response!

    The thing is, where I come from there aren't many robots. I'm assuming there are some in the heavy industries, but its not a common thing. This is why finding a guy is proving to be so difficult, the people who installed the existing bots were probably from abroad.. My employers long term end-game is to one day become the authority on industrial robots ourselves.

    I'm going to be honest, I kinda thought repeatability and accuracy were the same thing =/. Accuracy IS important to us, but I couldn't find an "accuracy spec" on any of the robots spec sheets, or am I missing something? I was looking for some sort of spec about the "steps" in the bots movements, like, whats the smallest movement the bot can make. Either way, a robot is more important to us than the highest accuracy. We rather get a relatively accurate robot than an extremely accurate CNC. I know the example of a task I gave is better suited for CNC, but thats just for the beginning while we learn. Eventually the tasks will be more complex and 3D.

    The E.O.A.T we are looking for are spindle, and fiber laser cutter. Hopefully getting an automatic tool changer later on. Fabrication is not a problem for us. We're pretty good at it ourselves, and if we feel we're not up for the task we have some good contacts for things like that. We have a lot of experience with wiring, 3 phase power isn't an issue. We don't have any experience with VFD's and if I'm completely honest, I don't even know what you mean by I/O? In/out? Input/output? How is this related?

    As for safety, theres no experience. Is there a standard I can look up and educate myself? I'm assuming E-stops are programmed stops in the bots movement that limit it from moving into a wall and things like that? That type of thing (and anything related to programming) is something I will teach myself.

    Can you recommend any resources for further information? By no means do I intend on being lazy and asking silly questions on forums to get other people to answer me. I Want to research things myself, its just that I can't seem to find alot of the information I am looking for and I don't completely know what it is that I need to research. I also understand this endeavor is too much for complete amateurs and that we will need some help from professionals, but I do want to be educated on the issue as much as possible first. I don't want to depend on others completely.

    Thank you so much for your help

    Hello everyone,

    It was unclear to me whether or not this was the right forum for this thread. I do apologize if its not.

    So, the company I work for is in the sound and light business. Buying, selling, installing and operating systems in this vain. My employer has had enough and now wants to move over to robotics. He will support and help me if I ask him to, but in general this thing has been made my responsibility.

    Of course it would be better to hire a professional "robot guy" to help us, but we haven't found one yet, the country I live in doesn't have many robots in industry. What kind of qualifications am I looking for in such a "robot guy" anyway?

    I have spent a few hours online doing research and feel completely overwhelmed, not least because most my google searches have yielded nothing useful - I suspect I lack some basic terminology...

    Finding vendors who sell used and refurbished robots was easy enough (we are looking mostly for KUKA or ABB), but I cant seem to find anywhere that sells E.O.A.T or "turntables".

    Obviously, purchasing a robot is the least of our worries, we also need to learn how to operate it. We have some basic CAD skills and I have been given the time to learn how to use fusion 360 (I can do that, I'm good with learning how to use programs), but I don't even know what I don't know... any help or pointers will be greatly appreciated.

    So here's the basic gist:

    At the beginning we are looking to use the robots mostly for cutting sheet metal and plastics. To that end, we want to purchase a fiber laser cutter able to cut through metals of ~6mm thickness. We need an arm with a reach of ~2m and the precision of ~0.06mm. We are also looking for a spindle tool that will be used to cut plastics of similar dimensions. We are also exploring the idea of robot CNC and milling of foam sculptures.

    To make my question a little more specific, the first task given to the robot will probably be cutting sheet metal in 2D. For example, cutting a hoop of a certain dimension, then a long rectangle (which will later be bent around the hoop and welded, not necessarily by a robot), then a similar hoop out of plastic. Effectively making the parts for a lamp, to be assembled later by a technician. As our understanding of the robot grows, so the tasks given to the robot will become more complex. I understand the basic requirements I need to look for in the robot: load, reach, repeatability. What other requirements should I be looking for? What kind of skills do we need to acquire (by our selves, or by hiring people who have already acquired them) for a process such as mentioned above? What programs do we (or hired help) need to be familiar with? What do I not know that I do not know?

    I realize these are some very vague and general questions, any help will be greatly appreciated. I feel like I'm groping in the dark, I just need to be pointed in the right direction.

    Thank you,