[NJC]

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

[skullworks]

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.

[klick0]

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

[cyclestart]

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

[Big John T]

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

[rajan_dd]

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

[skullworks]

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.

[rajan_dd]

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.

[Big John T]

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

[cyclestart]

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.

[NJC]

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

[cbcnc]

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

Chris

[andy55]

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.

[Al_The_Man]

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

[samco]

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/emc...orted_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.

[Al_The_Man]

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.

[skullworks]

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 - [ame="http://youtube.com/watch?v=mxxdq6y8z8M"]http://youtube.com/watch?v=mxxdq6y8z8M[/ame]

[PCW_MESA]

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

[samco]

could you give some examples of this?

thanks
sam

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

[Al_The_Man]

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.