I wondered about the use of the term CNC but I think we know what we are talking about even if we are not technically using the right terms and I don't really think it is harmful or confusing.
I was wondering if you could detail the features of a control that make it industrial standard rather than a glorified plotter?
CNC is a specific form of motion control relating to machine tools that cut (burn, bend, etc.) various materials.
I have to disagree with you. CNC = Computer Numerically Controlled. What makes you think your answer is the correct one? Give me a valid reference that I can turn to that will validate your claim, instead of just taking your word for it.
There is a good amount of information on the web about making CNC controls, but don't expect most of it to perform at the industrial level.
And that is also BS. I have a machine that will output over 10,000 units a day. If that is not industrial, then tell me what is.
As far as I remember Chris_D's explanations about CNC
If you add to "computer numeric controlled" the word "cutting" meaning milling or lathing 3D pieces of metal (minimum aluminium)
You get what Chris_D means.
One big challenge is to code a motion smoothener and optimiser. If you want to cut a rectangle hole with rounded edges out of a cube of metal
or even a more complexe shape. The feedrate should not go down to zero and accelerate again while cutting is active. If you do that the feedrate of the tool must go
through a area where the ratio between rotation-speed and feedrate is bad. You will get vibrations and vibration marks on the cutted surface.
This will reduce the precision of the product, will accelerate aging of the tool and bearings.
If you want to avoid this with a simple XYZ-axis control you have to choose cutting speeds, feedrates that are uncritical to this. In most cases this will result in cutting "deepness" that is rather small.
(finishing cut all the time right from the start)
So a real good CNC-cutting control will analyse a complete motion-path and do complex calculations how the feedrate can be changed to stay inside the parameter-field
of good cutting results keeping up all parameters to achieve the best productivity. Maximum feedrate and cutting-deepness only limited through surface-requirements
(the surface to be flat in the µm-area) tool-lifetime and cutting-forces the machine can deal with.
This is a specialty of milling and lathing that has no equalent in processes like packaging, drawing lines, automated assembling etc.
The most clever CNC-cutting-control will variate even path-overlapping or edge-rounding depending of if it is milling from raw to the inner core or if it is close to finishing the shape
which requires more precision.
Non the less I think that the precision of products can achieve the level of what the machine can do.
It will take longer than with a industrial CNC-machine.
But for me personally that doesn't matter.
If something of what I have said should be wrong correct me. I'm always eager to learn more.
some time ago before the switch to the new forum I posted some 5 axis linear interpolative code that I wrote for one of my coating machines for medical products. It's written in spin so not very fast, but works fine for my application. the main function is: GO(X,Y,Z,W,R,S) that takes the desired 5 axis position and a speed value and drives from the current position to the desired position. I didn't need ramping for this particular machine so I didn't implement it, but shouldn't be terribly hard to put together if someone wants to use it. It is some very basic code that anyone building a CNC machine might be able to use.
Several years ago I stuffed a 4.5 axis linear interpolative control function into an SX in assembly, ( with ramping ). I haven't taken the time to get comfortable with PASM, but given the horsepower of the Propeller, I don't think it would be all that difficult to port the code over to the prop and add another axis or two as well.
I'm currently using a board I designed for another application, but could realistically use a "Purpose designed" CNC controller for some of my machines. ( heavy duty I/O, more power and signal filtering, etc) If I knew that there were others out there that might make use of such a board I would be more inclined to get busy on it. I was hoping to do this design with the "TurboPROP" but the Prop I has plenty of capability, I'm curious about how many people might be interested in a 5-6 axis step and direction, board with all the trimmings for controlling a CNC machine? ( Home, Spindle on/off, air, cutting fluid, clamp/unclamp, etc)
I already have a small board I designed with 3 props on it, one for operator interface stuff: keyboard, mouse, VGA, RS-232, the other two for general control and communication, I included a pad for an FTDI USB to serial chip but never actually hooked one up and tried it. The I/O's are through two 37D connectors at either end of the board so it is designed to be "Plugged in" to a larger board that might contain all the filtering, power and opto relay stuff. If anyone is interested... let me know.
Ken Bash
I like the idea of having a central location for CNC info. I
The laserplotters of the 80's were CNC machines. They cost $250,000 to $500,000 and took many hours to plot a double sided pcb photography of about 2"x8" (Apple ][ size). I am certain a prop could do this because what was fed to the CNC machine was a set of "D codes". Things improved with the PC because the D code output could be optimised.
Most CNC controllers don't do the bulk of the optimization work, it's the software that generates the tool path in the first place. Typically you have a part that you want to cut out, and you use CAD/CAM software to produce the cutting paths. This software is given information about the diameter & depth of your cutting tools, feed rates, dimensions of your raw material, and so on. From there, it produces the raw cutting paths, rounds corners, optimizes connections between cuts, attempts to minimize non-cutting moves, and so on. It finds the most optimal cutting path it can given your parameters, and outputs it as GCode, which is a standard motion control language used by CNC machine controller software.
GCode is kind of like LOGO - At it's core it's little more than "Goto X,Y,Z" statements, with some extra info thrown in about speed, and the ability to do arcs. The hard part of the controller software is dealing with acceleration ramping. The machine cannot instantly begin moving at full speed - anything with a bit of mass needs to be sped up and slowed down. A simple controller will do this for every single command.
A more complex controller will read ahead of the current command to see if the upcoming commands are continuations of the current one. For example, lots of CAM software outputs curves as a sequence of very short line segments. Simplistic control software without lookahead will choke on a sequence like this. Mach3 will figure out that the next move in the sequence is close enough to the current direction that it doesn't need to stop first. Coordinating the slight curve between linear cuts like this is tricky. My machine does 8000 steps per inch at up to 180 inches per minute, which is 24,000 steps per second. Maintaining that rate while performing a smooth join between a linear cut and a radial arc requires some fairly heavy lifting.
In addition, GCode is a text format, with floating point (fixed-point decimal, usually) numbers. Just parsing the text itself would take some effort on the prop. I've run cuts where the GCode was 10mb or bigger - just lots of teeny linear moves.
To top it all off, you need to be able to stop the thing on a moments notice for safety, and Mach3 will accept positional feedback so if the steppers miss steps it can be corrected. The inner loop to deal with all of this is probably pretty ugly. Babinda's idea of pre-processing the GCode into linear moves to be passed to the Prop sounds quite promising, as it'd deal with all the parsing and constant velocity issues in advance. I wouldn't be surprised if the high-end controllers did something like this when you loaded the GCode - it makes a lot of sense.
I tend to agree with Chris that CNC has been co-opted to mean "automation" in many cases, but I also think the line is blurring. CNC has tended to mean computer controlled machining, IE highly programmable automation where the machine does not have a specific preset function. I think the assembly robots in an automotive plant qualify - They have many degrees of freedom, offer positional feedback, and require closed-loop computer control, so that's "computer numerical control" by definition. On the other hand, a straight metal stamping machine probably doesn't qualify - it has a single function, and is "triggered", not "controlled".
I've been wanting to build my own CNC machine. Right now I'm just figuring out what my design should be. So the actual control part is a ways off. but I like thinging about it.
I have a home made wood cutting CNC. using Mach3, with 3 of 4 Axis used.
I'm also a newbe to the Propeller chip, still using the basic2 stamp.
Just looking at the Propeller, haven't even finish reading the manual.
Those Plotters probably do not exist these days. While I watched one print once (boring because you cannot actually see the results. The plotter was probably 2m x 4m, maybe larger - it was huge! I am not sure whether it produced positives or negatives. That was before the raster days and I haven't seen what they use for the last 10 yrs.
I have to disagree with you. CNC = Computer Numerically Controlled. What makes you think your answer is the correct one? Give me a valid reference that I can turn to that will validate your claim, instead of just taking your word for it.
And that is also BS. I have a machine that will output over 10,000 units a day. If that is not industrial, then tell me what is.
Bruce
If we are to accept your concept that anything that is controlled by numbers is a CNC (Computer Numerically Controlled) then the following must be true
Cameras are CNC
Dishwashers are CNC
Electronic watches are CNC
VCRs are CNC
Automatic sprinklers are CNC
Printers are CNC
I dont ever recall a major manufacturer of any electronically controlled device being referred to as CNC controlled. True, they are controlled by a computer (micro) and they use numbers, but they are not referred to as CNC.
CNC has its roots in the machine tool industry, specifically its origins are that application to milling machines. Walk through any machine tool show and look at what is referred to as a CNC machine and what is referred to as a robot, they are not the same thing.
For further clarification, visit the FANUC websites and look through the information regarding CNC controls and the information pertaining to robotics and pick & place devices etc. Again you will see a distinction in how they are defined.
As for myriad of hobby level CNC control products (completed or abandoned) being at the level of performance equal to that of an industrial CNC control, show me one. More specifically, show me one that can control the following CNC machine
Twin spindle lathe, each spindle having 4 axis of motion X,Y,Z, and C, with a servo driven turret (not actually an axis of motion), glass scale feedback on X & Z axis for true closed loop operation, 2 axis gantry loader system, and all of the related hardware to support such a machine tool.
Finally, you seem to indicate that the hobby level controls that I refer to are industrial level, perhaps you care to inform us of any high-level machine tool companies that are using these controls on their industrial machines. While I did see MACH software used on a very small bench top mill at IMTS, I dont recall seeing either EMC or MACH on any large scale machine tools. Having worked in the machine tool industry for the better part of the last 30 years, I know first hand how price competitive this industry is. If there is a reliable CNC control that can replace: Fanuc, Yaskawa, Siemens, Mitsubishi, etc. a machine tool builder would be using it.
I understand why you hold this position, in industry the term CNC is used for machine tools and nothing else however that does not make it an invalid term for other machines. The fact that a camera or a washing machine is not referred to as CNC does not mean it is not CNC. For example we say digital camera or digital radio but we never say digital calculator or digital computer, the latter two items are digital but there is not point labelling them as such. Similarly a plotter does not need to be defined as CNC because they all are. CNC in the machine tool industry is a required label because if you just say lathe then it is not know if it is manual or computer controlled, before now you also had nc control to confuse matters. For automation products there are similar reasons for not stating that they are CNC, if the machine packages the item then what difference does it make if it does so by the use of cams or servos, no need to specify so the term is not used. Same with robots, non-CNC robots are called cranes.
The question really is why it this a problem? Is it just pedantry or does it cause an actual problem? I think we know what we are talking about. When you talk of confusion then it seems you really mean that these confused people are just wrong. Of course the other matter is that the definition of words comes down to usage not law.
The example you give of the lathe is indeed an impressive machine, I am sure there are also plenty of industrial controls that could not handle it. But really it seems an issue of scale as much as anything. But saying MACH/EMC or others cannot handle this is a far cry from them being glorified plotter drivers. You don't find EMC/MACH in large scale industry but they do work and I have seen EMC at least used on some large machines with many axes.
Luckily I don't think anyone is actually trying to build large machines with dozens of axes so I'm struggling to see the problem. It sounds a little like you are just trying to stamp your authority on the subject and show everyone how ignorant they are.
If we are to accept your concept that anything that is controlled by numbers is a CNC (Computer Numerically Controlled) then the following must be true…
Okay, I can relate to your saying, but I would definitely say those item are cnc. Maybe not heavy industrial equipment CNC, but still CNC. However the usage has changed in the last forty years. And I don't care what anybody says, my HP LaserJet 6L printer is a fine piece of CNC equipment I have had this thing 12 years and it still prints like the day I bought it.
I have a Grizzley Mini-Mill that I would LOVE to add 3 axis CNC to. On many occasions, I have started to put together a "buy list", but never got it all together! There are a lot of choices out there (dizzying at times), and the cost seems to be all over the place.
It would be GREAT to have a Propeller based solution - I believe that might just motivate me to finally do it!
One of the biggest problems that you will have is determining the size motors that you need to run the machine and then finding the appropiate drivers to run the motors. Take your time and evaluate this carefully, because a mistake in this area will cost you money and grief. I would also suggest to buy your drivers instead of making them, this will also save you grief. I am happy with my Gecko Drives and Applied Motion Product motors. Depending on the size motor you need, for a dependable three axis machine that can run off a Propeller chip you are looking at approximately a $650 investment for motors and drivers, however, you can find packages for less.
@Paul Sr
Is it the X2(G8689), or X3(G0463) you got from grizzly? I only ask, since the cnc machine i converted over was a X3 from grizzly, i can share the setup info if its the same. Also, have you been to www.cncfusion.com? where you can get kits for an easy conversion for both these mills, they have a forum where you can see other people's setups or ask for opinions on torque specs for motors etc used for your exact mill (X2 or X3). Which was really helpful.
I did a quick search with the keywords " Grizzley Mini-Mill" the hit that suits most in my opinion is this picture http://mini-machine.com/G8689.JPG
It seems to be from the manufacturer SIEG
In germany there is a website that offers CNC conversion-kits for the Sieg X3 and some other
small mills
.
There is a blog about the conversion to CNC of a Sieg X3 http://www.einfach-cnc.de/x3_version_3.html
The conversion-kit includes recirculating ball screws wich have no forward/backward play as trapeciodal screws.
This kit is 1230 Euro = $1635
From the picture I found I guess your Grizzly Mini Mill is a bit smaller
If you could provide the dimensions of your machine the comparison would be easier.
If you take a look at the technichal data the steppermotor used for the Sieg X3 is a
Sanyo Denki 103 H7823 1740
Current 4A
torque 3 Nm (not Ncm!)
price 79 Euro = $105
So this gives you a raw estimation of how strong the steppermotors should be
If your mill is really smaller than the X3 it might be enough to use the
Sanyo Denki 103 H7126 1740
4A
but torque just 1,65Nm
price 59 Euro = $79
If you ask me add $75 for using three bigger steppermotors with twice the torque.
I'm not a real expert about CNC-machines. Bit I got the impression that the guy
who created this website http://www.einfach-cnc.de has done quite a lot research on which components
are good for small CNC-mills. He wrote some books about hobby CNC-machines.
I understand why you hold this position, in industry the term CNC is used for machine tools and nothing else however that does not make it an invalid term for other machines. The fact that a camera or a washing machine is not referred to as CNC does not mean it is not CNC. For example we say digital camera or digital radio but we never say digital calculator or digital computer, the latter two items are digital but there is not point labelling them as such. Similarly a plotter does not need to be defined as CNC because they all are. CNC in the machine tool industry is a required label because if you just say lathe then it is not know if it is manual or computer controlled, before now you also had nc control to confuse matters. For automation products there are similar reasons for not stating that they are CNC, if the machine packages the item then what difference does it make if it does so by the use of cams or servos, no need to specify so the term is not used. Same with robots, non-CNC robots are called cranes.
The question really is why it this a problem? Is it just pedantry or does it cause an actual problem? I think we know what we are talking about. When you talk of confusion then it seems you really mean that these confused people are just wrong. Of course the other matter is that the definition of words comes down to usage not law.
The example you give of the lathe is indeed an impressive machine, I am sure there are also plenty of industrial controls that could not handle it. But really it seems an issue of scale as much as anything. But saying MACH/EMC or others cannot handle this is a far cry from them being glorified plotter drivers. You don't find EMC/MACH in large scale industry but they do work and I have seen EMC at least used on some large machines with many axes.
Luckily I don't think anyone is actually trying to build large machines with dozens of axes so I'm struggling to see the problem. It sounds a little like you are just trying to stamp your authority on the subject and show everyone how ignorant they are.
Graham
Graham,
I don't know if you are trying to escalate this into a fight or what. I am attempting to prevent exactly what your last statement is saying. If people are stating something incorrectly, by accident or by intent, I am trying to provide clarification. I have no intention what so ever to point out someone's ignorance. My intentions are that of educating, not insulting!
Further back in your comments you indicate that I do not believe EMC or MACH is capable of being anything more than a glorified plotter - this is not what I stated at all. In fact I use MACH on a couple of my hobby machines and it is very good software. Furthermore I believe it can be used to control basic industrial machine tools. The same is probably true of EMC but I have not spent anytime working with it. I did indicate that I did not see either of those controls being accepted by any major machine tool company as their CNC control of choice.
My comment using the comparision to "a tiny step beyond that of a basic X-Y plotter" had nothing to do with MACH or EMC. It is in reference to information published by people on the net. Most of them are nobel efforts, they achieved some rudimentary level of synchronized velocity and positional control.
Perhaps I am bit too uptight about how CNC is miss-applied. But working as an engineer in the CNC industry for many years, I have had to deal with muti-million dollar machine tool transactions with some of the largest companies in the world. When trying to differniate the many different devices in a cellular package, you use the proper, industry accepted terms to avoid confusion. If FANUC robotics refers to their robots as CNC machines, I would too, however, they don't, so I don't.
In the future, should you wish to pursue conflict with me, do not miss-quote me and do not imply my attempts are to insult others. I have no desire to insult people or to miss-guide them, nor do I have the desire to continue this dispute over terminology.
As I will NOT fight with You on CNC naming convention
> I will start New name to what we will accomplish "MCNC - Micro Computer Numerically Controlled" --- That maybe will satisfy You.
BUT at other said CNC are Sample name for all type of "Computer Numerically Controlled" ----> That said It is very DUMB machine that can't not do anything without additional Programing Input from their Operator else Other more advanced COMPUTER.
As I understand MACH3 ---> It is not any more that only INTERPRETER software between YOURS CadCam/Autocad/Layout and like program and LANGUAGE used to control Z/X/Y (Maybe more) axes by MCNC/CNC machine NOT more.
I don't know if you are trying to escalate this into a fight or what. I am attempting to prevent exactly what your last statement is saying. If people are stating something incorrectly, by accident or by intent, I am trying to provide clarification. I have no intention what so ever to point out someone's ignorance. My intentions are that of educating, not insulting!
Further back in your comments you indicate that I do not believe EMC or MACH is capable of being anything more than a glorified plotter - this is not what I stated at all. In fact I use MACH on a couple of my hobby machines and it is very good software. Furthermore I believe it can be used to control basic industrial machine tools. The same is probably true of EMC but I have not spent anytime working with it. I did indicate that I did not see either of those controls being accepted by any major machine tool company as their CNC control of choice.
My comment using the comparision to "a tiny step beyond that of a basic X-Y plotter" had nothing to do with MACH or EMC. It is in reference to information published by people on the net. Most of them are nobel efforts, they achieved some rudimentary level of synchronized velocity and positional control.
Perhaps I am bit too uptight about how CNC is miss-applied. But working as an engineer in the CNC industry for many years, I have had to deal with muti-million dollar machine tool transactions with some of the largest companies in the world. When trying to differniate the many different devices in a cellular package, you use the proper, industry accepted terms to avoid confusion. If FANUC robotics refers to their robots as CNC machines, I would too, however, they don't, so I don't.
In the future, should you wish to pursue conflict with me, do not miss-quote me and do not imply my attempts are to insult others. I have no desire to insult people or to miss-guide them, nor do I have the desire to continue this dispute over terminology.
sorry if I misunderstood you, I was referring to your original post and reading it there is no way to know exactly what you are referring to:
"Most of the hobbiest have gone down the road of a PC as a CNC control and its obvious advantage is its ability to crunch numbers and ofcourse massive memory and storage capacity. There is a good amount of information on the web about making CNC controls, but don't expect most of it to perform at the industrial level. Many of the control examples I have seen are just a tiny step beyond that of a basic X-Y plotter."
Now I understand you are referring to hobbiests that are trying to create their own controls rather than those just using PC based controls (which would be mach and EMC often). Making a control can mean designing from scratch or combining hardware and software, I hope you see the potential for confusion.
I did not mean to imply that you would wish to insult others but as I noticed in another thread you like to lecture and this can come across as a wish to show your superiority especially with industrial experience used as a reference. I chose my original words "sounds like" carefully, that is what it sounds like, only you can know the truth of course and I am happy to accept that your only motives are educational.
Mach3's role is to take in g-codes which represent the moves required by the machine and then interpret them and convert them in to step and direction signals that are sent to the stepper motor drivers. So it is an interpreter but also has to perform motion control (acceleration/decelleration, syncronization of axes) and pulse generation. For things like constant velocity profiling and multi axis synchronization it is not so simple. The machines themselves do not have a control language. A micro or two can perform this role as well.
Yet another CNC enthusiast here. Currently, I'm converting a Sharp knee mill (Bridgeport clone), which was fitted with ballscrews and X & Y servos back in the 90s, but the controller is totally shot. The motors run at 100V, so I'm using Dugong drives (http://www.shop.cncdrive.com/index.php?productID=166), not Geckos. Breakout board from CNC4PC (http://www.cnc4pc.com/Store/osc/index.php?cPath=33). They have boards which allow my VFD (converts 3 phase to single) to be controlled via Mach3 on a PC, which is what I'll use for control (I'm kind of looking forward to designing my own Flash screens, once I get everything running correctly). I'm also considering the SmoothStepper board for an improved pulse stream, but see it as optional at this point.
Don't know if I'll use the knee or spindle for Z, yet. I'll probably end up converting both, and then selecting one or other depending on job.
Making my own pendant is appealing, but there's actually an Xbox360 controller plug-in for Mach3 that makes that option hard to beat from a $$ perspective. What else? I'll integrate optical home & limit switches. I've also got pieces and plans for a pneumatic draw-bar opener, and will do electronic Z touch-off, edge & center finding, and probably probing.
As for the "What is CNC?" debate, I think of CNC as a motion control technology that moves axes with step and direction signals. Step and direction are typically described by g-code. For me, if you're commanding the step and direction of motors with g-code whether written by you or generated for you by design software, you're doing CNC (so dishwashers are out). However, I completely understand how, say, a CNC operator (a real vocation) would see this as an over-reach of the term.
Everyone just play and get along We must welcome Chris_D to our thread, even if if his definition is a little antiquated. Just kidding Chris_D. Someone told me yesterday that my opinion was half correct. My response: "I don't really care about how someone defines CNC, I have my own definition, and everyone is entitled to be ignorant". And of course that includes me.
I did not start this thread to debate the meaning of CNC. I started this thread to find out who and what is going on here concerning automation. And hopefully some good ideas and information would exchange hands. I am sure that everyone that has participated or will participate in this thread, has something to share even if it is just an idea, an ego rupture, or a beautiful piece of source code.
As I am sure you are all aware, I have already had my fill of arguing this week.
I think of CNC as a motion control technology that moves axes with step and direction signals. Step and direction are typically described by g-code. For me, if you're commanding the step and direction of motors with g-code whether written by you or generated for you by design software, you're doing CNC (so dishwashers are out). However, I completely understand how, say, a CNC operator (a real vocation) would see this as an over-reach of the term.
Now there is a fresh perspective!
CNC means to us as individuals how we ourselves interpret it's meaning, irregardless of anyone elses definition. Right or wrong, our own definitions will never changed by having each other cram definitions down each others throats.
I will be adding source code attachments applicable to "CNC" <-(by my definition) to the initial post of this thread. You may want to check periodically to see if there is something you may like to use.
Comments
I wondered about the use of the term CNC but I think we know what we are talking about even if we are not technically using the right terms and I don't really think it is harmful or confusing.
I was wondering if you could detail the features of a control that make it industrial standard rather than a glorified plotter?
Graham
I have to disagree with you. CNC = Computer Numerically Controlled. What makes you think your answer is the correct one? Give me a valid reference that I can turn to that will validate your claim, instead of just taking your word for it.
And that is also BS. I have a machine that will output over 10,000 units a day. If that is not industrial, then tell me what is.
Bruce
If you add to "computer numeric controlled" the word "cutting" meaning milling or lathing 3D pieces of metal (minimum aluminium)
You get what Chris_D means.
One big challenge is to code a motion smoothener and optimiser. If you want to cut a rectangle hole with rounded edges out of a cube of metal
or even a more complexe shape. The feedrate should not go down to zero and accelerate again while cutting is active. If you do that the feedrate of the tool must go
through a area where the ratio between rotation-speed and feedrate is bad. You will get vibrations and vibration marks on the cutted surface.
This will reduce the precision of the product, will accelerate aging of the tool and bearings.
If you want to avoid this with a simple XYZ-axis control you have to choose cutting speeds, feedrates that are uncritical to this. In most cases this will result in cutting "deepness" that is rather small.
(finishing cut all the time right from the start)
So a real good CNC-cutting control will analyse a complete motion-path and do complex calculations how the feedrate can be changed to stay inside the parameter-field
of good cutting results keeping up all parameters to achieve the best productivity. Maximum feedrate and cutting-deepness only limited through surface-requirements
(the surface to be flat in the µm-area) tool-lifetime and cutting-forces the machine can deal with.
This is a specialty of milling and lathing that has no equalent in processes like packaging, drawing lines, automated assembling etc.
The most clever CNC-cutting-control will variate even path-overlapping or edge-rounding depending of if it is milling from raw to the inner core or if it is close to finishing the shape
which requires more precision.
Non the less I think that the precision of products can achieve the level of what the machine can do.
It will take longer than with a industrial CNC-machine.
But for me personally that doesn't matter.
If something of what I have said should be wrong correct me. I'm always eager to learn more.
best regards
Stefan
some time ago before the switch to the new forum I posted some 5 axis linear interpolative code that I wrote for one of my coating machines for medical products. It's written in spin so not very fast, but works fine for my application. the main function is: GO(X,Y,Z,W,R,S) that takes the desired 5 axis position and a speed value and drives from the current position to the desired position. I didn't need ramping for this particular machine so I didn't implement it, but shouldn't be terribly hard to put together if someone wants to use it. It is some very basic code that anyone building a CNC machine might be able to use.
Several years ago I stuffed a 4.5 axis linear interpolative control function into an SX in assembly, ( with ramping ). I haven't taken the time to get comfortable with PASM, but given the horsepower of the Propeller, I don't think it would be all that difficult to port the code over to the prop and add another axis or two as well.
I'm currently using a board I designed for another application, but could realistically use a "Purpose designed" CNC controller for some of my machines. ( heavy duty I/O, more power and signal filtering, etc) If I knew that there were others out there that might make use of such a board I would be more inclined to get busy on it. I was hoping to do this design with the "TurboPROP" but the Prop I has plenty of capability, I'm curious about how many people might be interested in a 5-6 axis step and direction, board with all the trimmings for controlling a CNC machine? ( Home, Spindle on/off, air, cutting fluid, clamp/unclamp, etc)
I already have a small board I designed with 3 props on it, one for operator interface stuff: keyboard, mouse, VGA, RS-232, the other two for general control and communication, I included a pad for an FTDI USB to serial chip but never actually hooked one up and tried it. The I/O's are through two 37D connectors at either end of the board so it is designed to be "Plugged in" to a larger board that might contain all the filtering, power and opto relay stuff. If anyone is interested... let me know.
Ken Bash
I like the idea of having a central location for CNC info. I
Tell me more about these plotters.
Did it create negatives?
If so, how?
Bruce
Most CNC controllers don't do the bulk of the optimization work, it's the software that generates the tool path in the first place. Typically you have a part that you want to cut out, and you use CAD/CAM software to produce the cutting paths. This software is given information about the diameter & depth of your cutting tools, feed rates, dimensions of your raw material, and so on. From there, it produces the raw cutting paths, rounds corners, optimizes connections between cuts, attempts to minimize non-cutting moves, and so on. It finds the most optimal cutting path it can given your parameters, and outputs it as GCode, which is a standard motion control language used by CNC machine controller software.
GCode is kind of like LOGO - At it's core it's little more than "Goto X,Y,Z" statements, with some extra info thrown in about speed, and the ability to do arcs. The hard part of the controller software is dealing with acceleration ramping. The machine cannot instantly begin moving at full speed - anything with a bit of mass needs to be sped up and slowed down. A simple controller will do this for every single command.
A more complex controller will read ahead of the current command to see if the upcoming commands are continuations of the current one. For example, lots of CAM software outputs curves as a sequence of very short line segments. Simplistic control software without lookahead will choke on a sequence like this. Mach3 will figure out that the next move in the sequence is close enough to the current direction that it doesn't need to stop first. Coordinating the slight curve between linear cuts like this is tricky. My machine does 8000 steps per inch at up to 180 inches per minute, which is 24,000 steps per second. Maintaining that rate while performing a smooth join between a linear cut and a radial arc requires some fairly heavy lifting.
In addition, GCode is a text format, with floating point (fixed-point decimal, usually) numbers. Just parsing the text itself would take some effort on the prop. I've run cuts where the GCode was 10mb or bigger - just lots of teeny linear moves.
To top it all off, you need to be able to stop the thing on a moments notice for safety, and Mach3 will accept positional feedback so if the steppers miss steps it can be corrected. The inner loop to deal with all of this is probably pretty ugly.
I tend to agree with Chris that CNC has been co-opted to mean "automation" in many cases, but I also think the line is blurring. CNC has tended to mean computer controlled machining, IE highly programmable automation where the machine does not have a specific preset function. I think the assembly robots in an automotive plant qualify - They have many degrees of freedom, offer positional feedback, and require closed-loop computer control, so that's "computer numerical control" by definition. On the other hand, a straight metal stamping machine probably doesn't qualify - it has a single function, and is "triggered", not "controlled".
I found today nice Control-panel to my CNC that I collect parts to.
I'm also a newbe to the Propeller chip, still using the basic2 stamp.
Just looking at the Propeller, haven't even finish reading the manual.
That one I saw Printed directly on photo-resist that was on top of Copper
If we are to accept your concept that anything that is controlled by numbers is a CNC (Computer Numerically Controlled) then the following must be true
Cameras are CNC
Dishwashers are CNC
Electronic watches are CNC
VCRs are CNC
Automatic sprinklers are CNC
Printers are CNC
I dont ever recall a major manufacturer of any electronically controlled device being referred to as CNC controlled. True, they are controlled by a computer (micro) and they use numbers, but they are not referred to as CNC.
CNC has its roots in the machine tool industry, specifically its origins are that application to milling machines. Walk through any machine tool show and look at what is referred to as a CNC machine and what is referred to as a robot, they are not the same thing.
For further clarification, visit the FANUC websites and look through the information regarding CNC controls and the information pertaining to robotics and pick & place devices etc. Again you will see a distinction in how they are defined.
As for myriad of hobby level CNC control products (completed or abandoned) being at the level of performance equal to that of an industrial CNC control, show me one. More specifically, show me one that can control the following CNC machine
Twin spindle lathe, each spindle having 4 axis of motion X,Y,Z, and C, with a servo driven turret (not actually an axis of motion), glass scale feedback on X & Z axis for true closed loop operation, 2 axis gantry loader system, and all of the related hardware to support such a machine tool.
Finally, you seem to indicate that the hobby level controls that I refer to are industrial level, perhaps you care to inform us of any high-level machine tool companies that are using these controls on their industrial machines. While I did see MACH software used on a very small bench top mill at IMTS, I dont recall seeing either EMC or MACH on any large scale machine tools. Having worked in the machine tool industry for the better part of the last 30 years, I know first hand how price competitive this industry is. If there is a reliable CNC control that can replace: Fanuc, Yaskawa, Siemens, Mitsubishi, etc. a machine tool builder would be using it.
Chris
I understand why you hold this position, in industry the term CNC is used for machine tools and nothing else however that does not make it an invalid term for other machines. The fact that a camera or a washing machine is not referred to as CNC does not mean it is not CNC. For example we say digital camera or digital radio but we never say digital calculator or digital computer, the latter two items are digital but there is not point labelling them as such. Similarly a plotter does not need to be defined as CNC because they all are. CNC in the machine tool industry is a required label because if you just say lathe then it is not know if it is manual or computer controlled, before now you also had nc control to confuse matters. For automation products there are similar reasons for not stating that they are CNC, if the machine packages the item then what difference does it make if it does so by the use of cams or servos, no need to specify so the term is not used. Same with robots, non-CNC robots are called cranes.
The question really is why it this a problem? Is it just pedantry or does it cause an actual problem? I think we know what we are talking about. When you talk of confusion then it seems you really mean that these confused people are just wrong. Of course the other matter is that the definition of words comes down to usage not law.
The example you give of the lathe is indeed an impressive machine, I am sure there are also plenty of industrial controls that could not handle it. But really it seems an issue of scale as much as anything. But saying MACH/EMC or others cannot handle this is a far cry from them being glorified plotter drivers. You don't find EMC/MACH in large scale industry but they do work and I have seen EMC at least used on some large machines with many axes.
Luckily I don't think anyone is actually trying to build large machines with dozens of axes so I'm struggling to see the problem. It sounds a little like you are just trying to stamp your authority on the subject and show everyone how ignorant they are.
Graham
Okay, I can relate to your saying, but I would definitely say those item are cnc. Maybe not heavy industrial equipment CNC, but still CNC. However the usage has changed in the last forty years. And I don't care what anybody says, my HP LaserJet 6L printer is a fine piece of CNC equipment
Bruce
It would be GREAT to have a Propeller based solution - I believe that might just motivate me to finally do it!
One of the biggest problems that you will have is determining the size motors that you need to run the machine and then finding the appropiate drivers to run the motors. Take your time and evaluate this carefully, because a mistake in this area will cost you money and grief. I would also suggest to buy your drivers instead of making them, this will also save you grief. I am happy with my Gecko Drives and Applied Motion Product motors. Depending on the size motor you need, for a dependable three axis machine that can run off a Propeller chip you are looking at approximately a $650 investment for motors and drivers, however, you can find packages for less.
Bruce
Is it the X2(G8689), or X3(G0463) you got from grizzly? I only ask, since the cnc machine i converted over was a X3 from grizzly, i can share the setup info if its the same. Also, have you been to www.cncfusion.com? where you can get kits for an easy conversion for both these mills, they have a forum where you can see other people's setups or ask for opinions on torque specs for motors etc used for your exact mill (X2 or X3). Which was really helpful.
That was very helpful information, thanks for providing that for him. And that is a good link also.
Bruce
I did a quick search with the keywords " Grizzley Mini-Mill" the hit that suits most in my opinion is this picture
http://mini-machine.com/G8689.JPG
It seems to be from the manufacturer SIEG
In germany there is a website that offers CNC conversion-kits for the Sieg X3 and some other
small mills
.
There is a blog about the conversion to CNC of a Sieg X3
http://www.einfach-cnc.de/x3_version_3.html
The conversion-kit includes recirculating ball screws wich have no forward/backward play as trapeciodal screws.
This kit is 1230 Euro = $1635
From the picture I found I guess your Grizzly Mini Mill is a bit smaller
If you could provide the dimensions of your machine the comparison would be easier.
If you take a look at the technichal data the steppermotor used for the Sieg X3 is a
Sanyo Denki 103 H7823 1740
Current 4A
torque 3 Nm (not Ncm!)
price 79 Euro = $105
So this gives you a raw estimation of how strong the steppermotors should be
If your mill is really smaller than the X3 it might be enough to use the
Sanyo Denki 103 H7126 1740
4A
but torque just 1,65Nm
price 59 Euro = $79
If you ask me add $75 for using three bigger steppermotors with twice the torque.
I'm not a real expert about CNC-machines. Bit I got the impression that the guy
who created this website http://www.einfach-cnc.de has done quite a lot research on which components
are good for small CNC-mills. He wrote some books about hobby CNC-machines.
best regards
Stefan
This is what I'm doing about CNC machines (not exactly a drilling PCB machine, but similar
http://www.youtube.com/watch?v=Te6mIzngmw0
And these are the boards I use, all is one propeller controlled.
Graham,
I don't know if you are trying to escalate this into a fight or what. I am attempting to prevent exactly what your last statement is saying. If people are stating something incorrectly, by accident or by intent, I am trying to provide clarification. I have no intention what so ever to point out someone's ignorance. My intentions are that of educating, not insulting!
Further back in your comments you indicate that I do not believe EMC or MACH is capable of being anything more than a glorified plotter - this is not what I stated at all. In fact I use MACH on a couple of my hobby machines and it is very good software. Furthermore I believe it can be used to control basic industrial machine tools. The same is probably true of EMC but I have not spent anytime working with it. I did indicate that I did not see either of those controls being accepted by any major machine tool company as their CNC control of choice.
My comment using the comparision to "a tiny step beyond that of a basic X-Y plotter" had nothing to do with MACH or EMC. It is in reference to information published by people on the net. Most of them are nobel efforts, they achieved some rudimentary level of synchronized velocity and positional control.
Perhaps I am bit too uptight about how CNC is miss-applied. But working as an engineer in the CNC industry for many years, I have had to deal with muti-million dollar machine tool transactions with some of the largest companies in the world. When trying to differniate the many different devices in a cellular package, you use the proper, industry accepted terms to avoid confusion. If FANUC robotics refers to their robots as CNC machines, I would too, however, they don't, so I don't.
In the future, should you wish to pursue conflict with me, do not miss-quote me and do not imply my attempts are to insult others. I have no desire to insult people or to miss-guide them, nor do I have the desire to continue this dispute over terminology.
Chris D
As I will NOT fight with You on CNC naming convention
> I will start New name to what we will accomplish "MCNC - Micro Computer Numerically Controlled" --- That maybe will satisfy You.
BUT at other said CNC are Sample name for all type of "Computer Numerically Controlled" ----> That said It is very DUMB machine that can't not do anything without additional Programing Input from their Operator else Other more advanced COMPUTER.
As I understand MACH3 ---> It is not any more that only INTERPRETER software between YOURS CadCam/Autocad/Layout and like program and LANGUAGE used to control Z/X/Y (Maybe more) axes by MCNC/CNC machine NOT more.
sorry if I misunderstood you, I was referring to your original post and reading it there is no way to know exactly what you are referring to:
"Most of the hobbiest have gone down the road of a PC as a CNC control and its obvious advantage is its ability to crunch numbers and ofcourse massive memory and storage capacity. There is a good amount of information on the web about making CNC controls, but don't expect most of it to perform at the industrial level. Many of the control examples I have seen are just a tiny step beyond that of a basic X-Y plotter."
Now I understand you are referring to hobbiests that are trying to create their own controls rather than those just using PC based controls (which would be mach and EMC often). Making a control can mean designing from scratch or combining hardware and software, I hope you see the potential for confusion.
I did not mean to imply that you would wish to insult others but as I noticed in another thread you like to lecture and this can come across as a wish to show your superiority especially with industrial experience used as a reference. I chose my original words "sounds like" carefully, that is what it sounds like, only you can know the truth of course and I am happy to accept that your only motives are educational.
End of discussion for me, I'm sorry this blew up.
Graham
Mach3's role is to take in g-codes which represent the moves required by the machine and then interpret them and convert them in to step and direction signals that are sent to the stepper motor drivers. So it is an interpreter but also has to perform motion control (acceleration/decelleration, syncronization of axes) and pulse generation. For things like constant velocity profiling and multi axis synchronization it is not so simple. The machines themselves do not have a control language. A micro or two can perform this role as well.
Graham
Don't know if I'll use the knee or spindle for Z, yet. I'll probably end up converting both, and then selecting one or other depending on job.
Making my own pendant is appealing, but there's actually an Xbox360 controller plug-in for Mach3 that makes that option hard to beat from a $$ perspective. What else? I'll integrate optical home & limit switches. I've also got pieces and plans for a pneumatic draw-bar opener, and will do electronic Z touch-off, edge & center finding, and probably probing.
As for the "What is CNC?" debate, I think of CNC as a motion control technology that moves axes with step and direction signals. Step and direction are typically described by g-code. For me, if you're commanding the step and direction of motors with g-code whether written by you or generated for you by design software, you're doing CNC (so dishwashers are out). However, I completely understand how, say, a CNC operator (a real vocation) would see this as an over-reach of the term.
Everyone just play and get along
I did not start this thread to debate the meaning of CNC. I started this thread to find out who and what is going on here concerning automation. And hopefully some good ideas and information would exchange hands. I am sure that everyone that has participated or will participate in this thread, has something to share even if it is just an idea, an ego rupture, or a beautiful piece of source code.
As I am sure you are all aware, I have already had my fill of arguing this week.
Please Respect My Wishes
The Thread Starter
Bruce
Now there is a fresh perspective!
CNC means to us as individuals how we ourselves interpret it's meaning, irregardless of anyone elses definition. Right or wrong, our own definitions will never changed by having each other cram definitions down each others throats.
Bruce
I will be adding source code attachments applicable to "CNC" <-(by my definition) to the initial post of this thread. You may want to check periodically to see if there is something you may like to use.
Bruce