Hello all, I am considering using EMC to controll my Bridgeport. I am going to be doing a PC based software conversion to replace my old DOS controller. I was going to use Mach3 but have recently been told that my servo drives need PWM inputs and that Mach only has step and direction outputs. I was planning on using a Pico systems controller that uses PWM and John from Pico says his board works perfectly with EMC. I don't have any Linux experience at all, never used it. How do you like EMC? What are the pros and cons of the software? If you have used Mach3 and EMC, which do you like better? Is it user friendly?

Thanks.
Scott

Scott;

I admit I'm a computer geek and Linux is just another O/S to me.

But:

Get yourself a copy of the latest EMC2 Live CD - Don't even install it. Just boot to it and play with some of the SIM configs.

Actually Installing is almost as easy. The Live CD can do a Ubuntu Linux install with the EMC program allready setup in basic configs. The Pico Systems hardware drivers are allready in the EMC bundle.

Help is almost always available on the #EMC irc.

Try it, I think you will like it.

I've only ever used EMC to drive my machine, I love it, granted however I know nothing else. I recently purchased some equipment from pico systems (john) but have yet to use it, i'm building a new cnc machine and once it's done it'll be using the pico systems universal stepper controller.

EMC has always worked great for me though, no software failures (my cnc machine has screwed up before eheh, but that's my fault).

Ross

I was planning on using a Pico systems controller that uses PWM and John from Pico says his board works perfectly with EMC.
If you go this route you're married to emc afaik.

How do you like EMC?
Very much. Emc users are relatively small in numbers but large in enthusiasm.

What are the pros and cons of the software?

If you are used to a big brand CNC the control in emc can be a bit clumsy. Not sure if Mach fares much better in this type of comparison.

emc is much more than mill/lathe software. Most of us have only scratched the surface of it's capabilities as a machine control.

If you have used Mach3 and EMC, which do you like better?
Limited Mach experience. As a motion control it may be a sawoff. Realtime kernel has a theororetical advantage.

Compared to to Mach there is less documentation and fewer wizards. This gap is closing somewhat.

Is it user friendly?
If this is your first experience with *nix there is a learning curve. Ubuntu eases the transition a great deal.

Old linux joke: Linux is user friendly, it's just particular who it chooses for friends.
Don't let this scare you off :)

I used EMC on my plasma table and it is highly configurable. Some of the documents are a bit terse but the irc and mailing list is full of helpful people when you hit a snag.

Pros
It is open source
It is real time
It is configurable
It is being improved every day
It cost you nothing but some time to try it out

Cons
The docs are lacking
It won't work on a laptop afaik

Linux can take a bit to get use to if your a seasoned window user but, Unbuntu makes it as easy as possible...

Oh, yes don't forget the wiki site it is full of info...

John

Well, sounds like you all are happy with it, I was hoping to hear that. Sounds like the technical part of the software is very well thought out and works well. Maybe Mach has more bells and whistles, like the wizards. I was told that EMC allows use of the machine manually as well as with the controller and that Mach doesn't allow one to use it manually, is this true? Would be nice to be able to do simple tasks quickly without programming. I'm used to setting up my work now manually, I don't have a thumbwheel or anything like that, it's a real simple system, I kinda like it that way.

Thanks for all the unput!

Scott

Let's not forget about the fact that you don't need a super computer to run EMC2. I'm using it on a 650 mhz PIII. Well maybe a little faster would be better for the GUI. But Ubuntu Linux and EMC get along fine on simpler machines. Check the recommended hardware list.
EMC Wiki Hardware Requirements (http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Hardware_Requirements)

Chris

for generating PWM output there is also the Pluto-P which connects to the parallel port and the M5i20, a PCI card, so you might want to consider these too.

my machine is not a bridgeport but it uses DC-servos, pwm amplifiers from Jon Elson, and an m5i20 + EMC2 to control it all. Videos here:
http://www.cnczone.com/forums/forumdisplay.php?f=386

You mentioned manual machining. If you leave the handwheels on the mill you can use EMC2 or make a custom program to use your computer as a DRO - only displays coordinates no cnc control.

Has anyone got PC Motion Control Cards to work in EMC?
Al.

You have asked this a few times.. Maybe I need to ask - why do you think emc needs to support motion control cards? (really - I don't see a need). Emc2 does motion within itself. Any hardware that moves motion outside of emc isn't a good match. It would make emc2 not emc2 :). Emc2 only requires 'dumb' cards that count encoders and maybe a few dac's, adc's or PWM if your build requires that. Emc closes the pid loop within software.

I love this quote from one of the emc2 developers
Again - this goes back to emc2 being the motion controller. Equipment that moves the motion outside of emc isn't a good match. EMC is a closed-loop motion controller, unlike anything else that's affordable by hobbyists. Steppers only work because EMC fakes itself out with a made-up position value for the loop control.

I don't have experience with gali or such - is there anything that it does that emc doesn't? Price wise - how do they compare to emc supported hardware? 4/8 axis card from mesa with +/- 10v 4 axis card and 2 24 i/o isolation boards costs around 199+69X3=$406. this gives you 4 axis + 32in 16out. You can look at other hardware here.
http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?EMC2_Supported_Hardware

pico systems has some nice cards also.

(still - low budget you could even run PWM out the printer port and read encoders back in)

sam



Has anyone got PC Motion Control Cards to work in EMC?
Al.

You have asked this a few times.. Maybe I need to ask - why do you think emc needs to support motion control cards?

I have asked it a few times and have received mixed inconclusive answers.
May it is because I am not fully aware as to how EMC closes the loop?
If it is closed withing the EMC s/w, then I would have though it wuld have been open to other forms of servo drive control such as 10v analogue?
Also Does it support master/slave gearing and electronic cam etc?
Al.

Actually analog +/- 10V hardware is one of the best matches for EMC and can be implemented a number of different ways.

Step/Dir type servo drives which treat a servo like a high priced stepper drive are supported but waste much of EMC's capability.

Velocity mode (vrs steps) can run on a pIII-600 with marginal CPU loading - Try that on a Mach 3 based system.

Likewise EMC preferably homes using an Index (aka Z channel) - so E-Stop or powering a machine down doesn't require reseting all your offsets.

Emc also supports rigid tapping and being open source is constantly having new features added.

Often EMC may not support something because no one has yet had the need for a function, but things get added as needed.

A good example is 5 axis tool offsets...

Check out Stuart's Cinnci - http://youtube.com/watch?v=mxxdq6y8z8M

I have asked it a few times and have received mixed inconclusive answers.
May it is because I am not fully aware as to how EMC closes the loop?
If it is closed withing the EMC s/w, then I would have though it wuld have been open to other forms of servo drive control such as 10v analogue?
Also Does it support master/slave gearing and electronic cam etc?
Al.

In the servo case EMC closes the loop by reading actual position, comparing it with the desired position and outputing a control signal to the drive system to minimize the difference. The exact drive signal applied is calculated via a standard PID loop, just as in a 'smart' controller card.

The position input to EMC is typically done via quadrature, and the output signal is typically PWM or analog +-10.

EMC can do this with nothing more than a parallel port, with some encoder count speed and PWM resolution limitations. With decent hardware (Mesa. Pico, STG or Vital). EMCs servo performance is just as good as controllers that close the loop on the card, and has the advantage that all of the PID loop is in one place (and in the open). One reason this works as well as it does its that EMC runs under a true RTOS. 'Smart' controller cards are required by non-RTOS systems for decent performance, but not by EMC.

Peter Wallace

i came across this the other day and found it very interesting deffinitely makes emc a plus http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Steppers_With_Encoders

mach can t do this from what i understand

Hello all, I am considering using EMC to controll my Bridgeport. I am going to be doing a PC based software conversion to replace my old DOS controller. I was going to use Mach3 but have recently been told that my servo drives need PWM inputs and that Mach only has step and direction outputs.

Just a thought, by PWM do you mean quadrature or wave drive as it is called in Mach ?

Or are you talking something like locked antiphase or sign/magnitude?

If it is quadrature you need for your servo drives then I think the wave nc option in Mach will work with your drives directly, I am going to try this at some time, haven't quite got there yet.

Having said that I would think that EMC would output a quadrature signal as well...not sure about that, someone more knowledgable of EMC may want to comment.

Russell.

Just a thought, by PWM do you mean quadrature or wave drive as it is called in Mach ?

Or are you talking something like locked antiphase or sign/magnitude?

If it is quadrature you need for your servo drives then I think the wave nc option in Mach will work with your drives directly, I am going to try this at some time, haven't quite got there yet.

Having said that I would think that EMC would output a quadrature signal as well...not sure about that, someone more knowledgable of EMC may want to comment.

Russell.

Quadrature is an INPUT signal read from the position encoders...

Some stepper drives are driven using the winding step phases.

Quadrature is an INPUT signal read from the position encoders...

Some stepper drives are driven using the winding step phases.

It can also be used as an OUTPUT from PC to servo drive as in the case of the DSPIC servo drive which has a quadrature input from the controlling PC instead of step/dir, it also has quadrature input from the encoders.

Quad from a PC to servo drive is a form of step/dir. 'A' leading 'B' or 'A' trailing 'B' defines direction, and total counts define the move distance.

When Quad is only fed back to the servo drive from the motors (IE Gecko 320's) Then the system is semi open loop as the PC only knows that it has not received an error from the amp and that the servo is "somewhere" within the +/- 128 encoder counts it takes to fault the amp for a following error. Depending on screw pitch and encoder counts per revolution this error could be huge.

There are "BOB" 's that share encoder info with the PC but those are and exception to the rule for "hobby" type setups.

EMC comes from the other end, intended to replace controls on big iron if sources of commercial controls dried up (world conflict, embargos, etc.) Once proven the U.S. NIST project was eventualy shelved, and EMC2 grew out of its remains as a non-.gov opensource project. Much of the "Big Iron" roots are still around. Existing options include: Seperate home and limt switches. Oil lube alarm inputs. Home to Index Tool tables with both tool# and pocket# etc.... to name a few

EMC2 REQUIRES feedback. In the case of stepper systems and open loop servos EMC counts its output pulses and computes where the machine would be and feeds this back into itself to make up for the lack of true position input.

All I was getting at in my original post was that the servo drives mentioned by NJC may accept quadrature instead of step/dir, with the idea that he may be able to use either Mach or EMC without extra hardware, it may be that he has to use EMC if he doesn't want to buy more cards, as mentioned then EMC will take care of the motion control.

It just sounded funny that a servo drive would take just PWM input and nothing else, wouldn't that just make it a H Bridge ? Where were the encoders plugging in ?

I for one think EMC is great and I intend to use it as soon as I get time in my life, I seem to be forever building my router and never running it, something I hope to change.

Russell.

Well Russel you pretty much hit it on the head - most amps EMC uses are simple H-Bridges, no encoder inputs to the amps at all.

As such many of these amps are driven by straight PWM inputs. EMC likes these "dumb" amps as it is better to know where things are in one program than to have serveral "smart amps" running slightly out of sync.

could you give some examples of this?

thanks
sam

Also Does it support master/slave gearing and electronic cam etc?
Al.

could you give some examples of this?


A simple example is where a gantry has a motor fitted to ether sides of the X axis, and one is master and the second is slaved of the master encoder rate to enable synchronization.
In this case, the gearing would be 1:1 but any ratios can be programmed.
The Galil site has a few animated examples of gearing, http://www.galilmc.com/support/motioncode/index.html
they do not show the cam feature example however.
Also I would be interested to hear how the PMC/PLC side of the CNC controller is effected?
If it is like early CNC where there were basic CNC I/O communication to a stand-alone PLC or whether the CNC also carries out this task, if the RTOS is dedicated to the CNC control, does it co-process the PLC Machine functions?
Al.

A simple example is where a gantry has a motor fitted to ether sides of the X axis, and one is master and the second is slaved of the master encoder rate to enable synchronization.
In this case, the gearing would be 1:1 but any ratios can be programmed.
The Galil site has a few animated examples of gearing, http://www.galilmc.com/support/motioncode/index.html
they do not show the cam feature example however.
Also I would be interested to hear how the PMC/PLC side of the CNC controller is effected?
If it is like early CNC where there were basic CNC I/O communication to a stand-alone PLC or whether the CNC also carries out this task, if the RTOS is dedicated to the CNC control, does it co-process the PLC Machine functions?
Al.



Normally with multiple servo'ed axis (say in a gantry type machine) it would not be desirable to use one encoder as a master for the other servo channel, as the slaved axis would be less accurate because it would have the following errors of the master axis added to its own errors. In this case its usually better to have both axis follow the computer generated profile (trajectory). EMCs HAL file will allow setup of simple static gearing of this type.

For specific applications EMC does 'electronic gearing' where motion is slaved to the spindle encoder. Rigid tapping and multipass threading are examples of this gearing.

If PLC features are desired, EMCs PLC (Classic Ladder) can be added as a real time task, same as motion and I/O.

Peter Wallace

Hi, i found out u have used EMC for plazma, i even want to use it for plasma and oxi-fule cnc machine. my question is is there a function for retrace available in EMC.
i.e. when the cutting stops due to bad gas or dirt on plate an i reverse it a little and start the cutting again with out reseting the program

thanking you in advance

regards
Rajan

I used EMC on my plasma table and it is highly configurable. Some of the documents are a bit terse but the irc and mailing list is full of helpful people when you hit a snag.

Pros
It is open source
It is real time
It is configurable
It is being improved every day
It cost you nothing but some time to try it out

Cons
The docs are lacking
It won't work on a laptop afaik

Linux can take a bit to get use to if your a seasoned window user but, Unbuntu makes it as easy as possible...

Oh, yes don't forget the wiki site it is full of info...

John

This is one of the little issues currently in EMC and is getting increasing feedback as a feature request.

So to answer your question: - No there is not an easy way to restart at a given point - at this time.

I expect that this is one of the areas that will be getting increased attention in the future.

Thankyou for your reply. I really appreciate it.

I would just like to add i just dont want to restart but even retrace

Some controller has option of directly moving to a given block skipping all previous blocks, but there is problem with it. As the block in our application can sometimes be only about 1mm long while some times it can be hundreds of mm in length. For example there is a 800mm long straight cut and the cutting stops at 500mm (due to bad gas or dirt on the plate) and the operator presses stop as 505mm, it becomes necessary to move the machine 5mm back on the same trajectory and restart the cutting.

I gave the example so that my problem is clear as I need not just restarting from a given block but retracing.

I would even like to know where can I place a request for my required feature in EMC and where can I get the list of currently work in progress features.

Regards
Rajan

This is one of the little issues currently in EMC and is getting increasing feedback as a feature request.

So to answer your question: - No there is not an easy way to restart at a given point - at this time.

I expect that this is one of the areas that will be getting increased attention in the future.

he cutting stops at 500mm (due to bad gas or dirt on the plate) and the operator presses stop as 505mm, it becomes necessary to move the machine 5mm back on the same trajectory and restart the cutting.


So if the code is something like this

N??? some moves
N101 G00 X0
N102 G01 X800 F30
N??? more moves

you want to be able to stop the execution of line N102 midpoint, back up a few mm, and then restart? Interesting idea. I think currently the only way to restart is from the beginning of a line #. This means going back to X0 and repeating line N102.

This page explains feature requests;
http://www.linuxcnc.org/content/view/48/13/lang,en/
It says feature requests are best discussed on the mailing-lists before submission. Frankly this request will probably get a lukewarm reception. Nothing lost in discussing it however.

Edit/ I decided to read the user manual on this topic. WOW is this glossed over. What exactly to expect if a program is stopped/paused and the machine jogged? How to restart predictably in AXIS if you're doing more than pausing? My machine is in pieces so can't have a play with this idea. If no one answers here, do ask on the mailing-list.

You can restart in the middle of a program is you use Tkemc. Under 'File' , 'Edit' - there is a simple little editor that will pop up with your current program in it. Place your cursor on the line that you would like to start at and then click on the 'Set Run Mark' button. Be careful when you do this. You should be fully aware of what code is in effect and where your machine is (otherwise you could crash or worse).

When we are talking about EMC we should note that Axis is not EMC but just one gui for it. You could write your own gui for EMC with a little bit of effort by looking at the existing code for the 6 or 8 other guis in existance.

Thanks,
Dan

Looks like skullworks gave the best answer you're likely to get. Here's a thread from the mailing-list
http://thread.gmane.org/gmane.linux.distributions.emc.user/5943

Covers some things the manual misses.

We same time posted, hence the "best answer" remark. In this case 'best answer' meaning better than my answer ;)


When we are talking about EMC we should note that Axis is not EMC but just one gui for it.
yes, and full documentation for all should be the goal. Hope that doesn't sound ungrateful. The hard work put into this project is appreciated.

You could write your own gui for EMC with a little bit of effort by looking at the existing code for the 6 or 8 other guis in existance.

Well, maybe you could. As for some of the rest of us...... ;)

Can AXIS really not back up a little and resume? Works here on screen using set next line . Remember no machine hooked up at the moment.

Can AXIS really not back up a little and resume? Works here on screen using set next line . Remember no machine hooked up at the moment.

Wow, I didn't realize that was there. It just shows you how rusty I am. It's very easy to use too.
I learn something new every day....

Thanks,
Dan

Thankyou very much for so many replys, really appreciated it.

So if the code is something like this

N??? some moves
N101 G00 X0
N102 G01 X800 F30
N??? more moves

you want to be able to stop the execution of line N102 midpoint, back up a few mm, and then restart?
Yeah thats what exactly what i want.


Edit/ I decided to read the user manual on this topic. WOW is this glossed over. What exactly to expect if a program is stopped/paused and the machine jogged? How to restart predictably in AXIS if you're doing more than pausing? My machine is in pieces so can't have a play with this idea. If no one answers here, do ask on the mailing-list.
Currently i have a controller which is PC + PCI FPGA Board solution(both the pc software and FPGA HDL are programed by me) it can do the retrace in fact it can run whole program in reverse once i press the "R" key, but my code dose not have an trajectory planer, so it was easy implementing the feature in my system. now i want a trajectory planer in my system. and the problem is my maths is not very good, so i was looking in emc if i could get some help.

Can AXIS really not back up a little and resume? Works here on screen using set next line . Remember no machine hooked up at the moment.
I did tried what you are saying but it starts from beginning of the block not from the current location, more over what ur saying can be a solution if a computer literate person is operating the machine, my machine is operated by a person who cant even write properly, had never seen a computer before. he can just read the local language translation written on the switches which can start, stop, jog, reverse & forward the program. so i need a stupidly easy way to do it.
:drowning:

Im trying to look at the code of trajectory planer and the gui but its going to be really hard long nights trying to understand all that.

Regards
Rajan

Hi, i found out u have used EMC for plazma, i even want to use it for plasma and oxi-fule cnc machine. my question is is there a function for retrace available in EMC.
i.e. when the cutting stops due to bad gas or dirt on plate an i reverse it a little and start the cutting again with out reseting the program

thanking you in advance

regards
Rajan

Not that I know of. You would still have to restart the torch at the point you start back up so you would have to edit the code to insert the method you use for that...

John

I did tried what you are saying but it starts from beginning of the block not from the current location,
It does what I claim if done in an exact sequence.
-> press the stop button or <escape> key
-> jog back a bit
-> click on the line that would be next in order of execution
-> machine menu -> set next line
-> machine menu -> run program

note: I only checked the accuracy with a felt marker

This REALLY needs to be written into the user manual.

Rajan
You're obviously very bright and your english is excellent. It might be an idea to get onto the emc irc channel and discuss some of this with the developers.

edit/ oops, thought your location was indonesia . People in India speak English with a correctness that's being lost in North America. :)

Not that I know of. You would still have to restart the torch at the point you start back up so you would have to edit the code to insert the method you use for that...

John

Ah, guess this falls under the same category as the spindle restart problem.

I'm guessing the only way to "back up" is to do an MDI in the reverse direction. For example if I'm going from X0Y0 to X12Y6 and stop in mid stream via the stop button I guess (can't try it here) that a MDI G1X0Y0 "should" "reverse course" then stop again via the stop button (if that works during an MDI). At that point you could start over again... after you light off the torch.

John

We have a punch/cam grinder here that has a manual handle mode where the manual pulse generator becomes a feed rate input. The faster you turn it the faster it goes, and the real neat thing is if you turn it backward and you have a negative feed rate and it backs up thru the code very nicely.

I have been wanting that on a mill every since the first time I used it on the grinder, it would be great for setups and debugging new macro code. The grinder does not do macros, backing up thru most functions would be impossible without saving a history.
#100 = 1;
What was #100 before it was set to 1?

So it would only be practical to do on simple plain G-code, on which it would be of limited value.

First of all I’m really sorry for not replying to yr replies for so long, but work was keeping me very busy and I needed to think over and try some of things u all said, I’m sure if we go on like this then surely I can find out some great solution to my problem and hope it helps others too.


It does what I claim if done in an exact sequence.
-> press the stop button or <escape> key
-> jog back a bit
-> click on the line that would be next in order of execution
-> machine menu -> set next line
-> machine menu -> run program

Well yeah it does what u said can be useful to me, there is one problem if it’s a slant move we have to move both x and y axis individually. I would like to ask is there a way to do all this through some kind of script or some code. Like the program must go reverse when I press “R” and then start in forward direction when I press “S”.I would like to tell that my knowledge about EMC and Linux programming is not so good, though im trying to understand the EMC’s code and the way things r done in it.

Rajan
You're obviously very bright and your english is excellent. It might be an idea to get onto the emc irc channel and discuss some of this with the developers.
Well I will take that as a compliment, as English is my third (not second) language :)
Surely I will try irc channel when I have enough knowledge about EMC's code.

I'm guessing the only way to "back up" is to do an MDI in the reverse direction. For example if I'm going from X0Y0 to X12Y6 and stop in mid stream via the stop button I guess (can't try it here) that a MDI G1X0Y0 "should" "reverse course" then stop again via the stop button (if that works during an MDI). At that point you could start over again... after you light off the torch.
John
It would be great if all this can be done through some kind of script or some code as I replied to cyclestart. I’m trying the MIDI to see what can be done.

We have a punch/cam grinder here that has a manual handle mode where the manual pulse generator becomes a feed rate input. The faster you turn it the faster it goes, and the real neat thing is if you turn it backward and you have a negative feed rate and it backs up thru the code very nicely.

I have been wanting that on a mill every since the first time I used it on the grinder, it would be great for setups and debugging new macro code. The grinder does not do macros, backing up thru most functions would be impossible without saving a history.
#100 = 1;
What was #100 before it was set to 1?

So it would only be practical to do on simple plain G-code, on which it would be of limited value.

Actully i only have very simple code, with only M Code for torch start and stop nothing more.

It will take some very fancy programing iof what yopu want is even possible. I'm thinking that if you were in the middle pf an arc when you E-stopped, in order to go backwords, you would need the new end point (which would be changing continuously if you were using a joystick) and arc center.

or an angle the machine would look at the last point and head in that direction. What happens when cutter comp is used? If you are heading back the way you came, wouldn't the torch move over so it retains the cutter comp? Circles are clockwise and counter clockwise.

Sounds like a lot of code to consider.

It will take some very fancy programing iof what yopu want is even possible. I'm thinking that if you were in the middle pf an arc when you E-stopped, in order to go backwords, you would need the new end point (which would be changing continuously if you were using a joystick) and arc center.

or an angle the machine would look at the last point and head in that direction. What happens when cutter comp is used? If you are heading back the way you came, wouldn't the torch move over so it retains the cutter comp? Circles are clockwise and counter clockwise.

Sounds like a lot of code to consider.

If your in the middle of an arc and it's not 6' in diameter just back up to the start of the arc and start from there... nothing fancy needed.

John

Reverse program motion. - This is nothing new as far as a feature request.

The issue was first brought up (that I'm aware of) with reguards to motion control for Wire EDM and even complex Sinker EDM applications. The results were some adaptive feed M codes as a partial starting point and then it faded into the background (for 2 reasons, almost ZERO Demand for the feature, secondly the complexity or the code required to add the feature.)

I would not be surprised if this feature does become available at some point, I just wouldn't hold my breath.

I moved from Windows/KellyCam to EMC2 and many quirks/problems went away.
The motion is much smoother and more reliable. Accuracy and repeatibility also went up.

Then there is the configurability of EMC; if you can think of it, it can probably be done. I wanted more inputs & outputs for switches, LEDs, etc. and added a second parport. Within 30 minutes, I had separate home and limit switches working with LEDs to indicate their states.

I'm not a Linux guru but I have sucessfully manually configured Mandrake and Red Hat many times as various servers and at first, scoffed at Ubuntu for being too Mac-like (and I like Macs!) but after installing from the Live CD, I've gotten to really like it and even dual-boot XP and Ubuntu 804 at home.

Using a little IBM "Net-something" PC with 256MB RAM and a 800MHz PIII Celeron with the "next to latest" version of EMC2 running a homemade router/engraver with XYZ=22", 6", 2".

Then there is the documentation issue. I'd like to find some sort of 'man2pdf' script and print it all eventually. But for now, you're looking at some of the best documentation (CNCZone). And it's interactive!

Besides, having a Microsoft OS controlling expensive and/or dangerous machinery just scares me.

My $0.02,
Emory