Best (Cheap) CNC Software to Use

[dertsap]

i'm gearing up to use emc 2,its a nice interface and works pretty good ,axis has a really nice feel to it the only thing i find is ubuntu emc needs a fairly powerfull pc , there is also gcam a freeware that a guy can use on the linux system which is a nice little program , they've recently put out gcam for windows as well , it surprises me that i don t see anyone in the forums using it

[samco]

My 2 cents.

I have used turbocnc. It works quite well- easy to setup and use. I used it until I needed some form of look-ahead - constant velocity.

That is when I looked into the emc bdi disks. This was ok but the second I found emc2 I fell in love. Works on simple stepper machines all the way up to full blown servo machining centers and more (robot Kinematics).

The latest version 2.1.0 has lathe support also. The developers are constantly working to improve and add functionallity- they are a great bunch..

I am not a linux person.. this is my first real linux exposure. I was a little scared but ubuntu, which the live cd is based on, is very easy to use. You can download the live cd here http://www.linuxcnc.org/ and give it a whirl. It will alllow you to boot into ubuntu and try emc2 out without installing it on your hardrive.

It is running a 3 axis gantry right now but have been playing with servos to convert an old k&t machining center. It looks like it will do everything we need including pallet tranfers and tool changes.

Sorry about my ramblings. I am very impressed with the software. Here is a bit of what we are working on.
http://www.cnczone.com/forums/showthread.php?t=25929

sam

[tjonak]

I AM THINKING OF BUYING QUICKSTEP 3 AND I AM WONDERING IF IT IS AS EASY TO USE AS THE BANDIT SOFTWARE? THE BOOK I HAVE ON MACH 3 IS ABOUT 3/4 OF AN INCH THICK,COMPARED TO THE BANDITS 3/8 INCH. IN ONE DAY I WAS PRODUCING PARTS ON THE BANDIT,WHERE AS THE MACH 3 I JUST GAVE UP. TOO MUCH STUFF TO READ ABOUT THAT I WILL NEVER USE.I WOULD KEEP THE BANDIT , BUT CAN'T FIND ANYBODY OR PARTS TO FIX IT.---------TED

[silentreaper]

Stop yelling......

[DIY-Guy]

Originally Posted by samco ... (CLIP!) That is when I looked into the emc bdi disks. This was ok but the second I found emc2 I fell in love. Works on simple stepper machines all the way up to full blown servo machining centers and more (robot Kinematics). sam

Sam, I'm a newbie to this. Stepper machines are simpler because ...?

And servo machines are better, bigger, more accurate, or ...?

Software that runs different kinds of equipment is very interesting! Please, tell us more.

DIY-Guy "Transitioning from the creative side of computers to CNC."

[probinson]

Hey DIY-Guy,

OK, Here are the basics of stepper vs servo:

A stepper motor has 2 or more windings that are driven individually. When any windings are energized, the shaft turns until the magnetic field lines up with the energized coils and it stops there. The motor moves in discrete steps in the direction determined by sequencing the coils. This makes controlling a stepper motor very simple because you just tell the drive to move to the next step and the motor does it. All the controller needs to do is tell the motor to move and wait long enough for it to happen before sending a new command.

A servo motor is a DC motor and works much like the motor you would find in a small toy. You apply a voltage to it and it turns in one direction, reverse the voltage and it turns the other way. You also adjust how hard or fast it turns by controlling how much voltage you apply. The servo motor will turn forever until you remove power, unlike the stepper, which turns from one predefined step to the next. You need additional circuitry to read the motor position, calculate how far and in which direction the motor needs to turn, and adjust the power very quickly to make it happen. This makes controlling the servo motor much more complicated.

The stepper motor is much simpler but there are 2 major disadvantages. First, your speed is limited to how fast the motor can reliably make the individual steps. Secondly, the control program usually has no way of knowing if the step was actually successful. This one can be really bad because the program has lost track of where the machine really is once an error occurs. A mistake like making too deep a cut can completely screw up everything that follows.

Despite these shortcomings, the stepper motor is pretty much the way to go for a beginner at the hobby level. The machine is vastly simpler to build and control and there is a lot of software that was written just to make your basic 2.5 and 3 axis machines as easy to use as possible.

The added complexity of the servo motor does, of course, afford some serious advantages. The resolution of the servo drive is nearly infinite. Your position encoder determines your resolution not your servo motor. The servo motor power is also fully controlled and, being a DC motor, is much more powerful than a comparably sized stepper. Because both the resolution and power are independent of the resolution, the servo drive is also capable of incredible speeds and accuracy. As an extreme example of what the servo drive can do, there are actually machines out there using linear direct drive (no gears or ball-screws, just magnets and coils) and laser interferometers to detect the position which can move at over 10 meters per second and position to sub-micron accuracy.

This is getting quite long winded so let me just quickly touch on software side.

Mach3, TurboCNC, and the like are for stepper driven machines You will hear these programs referred to as open loop, which means they send motion commands but don’t directly monitor what the machine is actually doing. . You can only use servo motors with these if you use an external controller that accepts step and direction control. This, in essence, makes the servo behave like a stepper motor. The software won’t have real time position tracking but will gain the advantages of encoder controlled resolution, increased speed and power, and no accumulation of lost steps. ( When a stepper is overloaded or just can’t keep up then it misses steps and position errors accumulate but the servo controller keeps track of where the motor should be so any position error is temporary and corrects itself as soon as the servo can actually reach the commanded position.)

EMC is for servo drives and includes all the control required to coordinate multiple servo motors. It uses what’s known as closed loop control. It takes the position data from multiple encoders and generates the power values to drive the motors. EMC is also capable of controlling very complex machines which increases the difficulty in deciphering what you need to get it up and running with your hardware. You can use EMC with steppers by creating simulated feedback but that’s kind of like putting your lawnmower wheels an your Jaguar.

I hope I explained that well and that it helps you and others to sift through the options.

Pete