Smooth Steppers are finally available in UK !

[Jonathan]

Apparently the ethernet version is indeed far superior to USB in that it does not suffer from the grounding issues. However unless you have servos and the speed of the parallel port isn't enough for you, there is little to no point buying a smoothstepper (and even if you do have servos linuxCNC is superior because of closed loop control using the parallel port, but I won't go into that). I don't see the point of spending lots of money on an expensive board to patch up the shortcomings of an expensive program, when you can use a free alternative without the issues in the first place.


The main advantage of LinuxCNC over Mach3 using a parallel port is it runs on a real time kernel. This ensures that the pulse output from the parallel port has priority over everything else on the computer, so you don't get the timing inaccuracies inherent to Mach3 from Windows interrupting. With LinuxCNC if the computer appears to 'freeze' the machine will still run happily, since it's prioritised over everything including the mouse/keyboard. No matter how much you disable things in Windows, remove programs or whatever fundamentally Mach3 is not real time so timing errors will exist. The external motion control boards, such as the smoothstepper, can achieve 'smoother' performance and higher speed because they operate in real time. But LinuxCNC does that for free...


'But I'm not a computer geek and it takes twenty thousand years to set up' I hear you cry! It really doesn't - the installation and setup process which apparently is such a huge barrier to many, is quicker, easier and more intuitive than windows/mach3. Owning a CNC machine makes you a geek to start with so it's too late for that anyway. In fact, the interface eliminates many human errors - I see countless problems from people setting the wrong value for steps/mm, whereas in linuxcnc, each pulley has its own textbox, meaning that you never have to do any fiddly arithmetic manually. Another example is the constant velocity mode - in Mach3 constant velocity mode is some arbitary value you can't control, whereas in LinuxCNC, you can precisely control the extent. I'm pretty sure that alone would make a bigger difference than Mach/SS. Those are just two examples of why LinuxCNC is widely accepted to be a lot more customisable and flexible than any Mach3 based controller.

'But I've used mach3 all my life and I'm used to it' - So you're considering paying hundreds of pounds just so you don't have to get used to something new, which has many advantages anyway? That doesn't make sense to me, and it seems very archaic.


Another crucial disadvantage of Mach3, or rather windows is its inability to perform on low end computers - with some ebay sniping (gixen.com), it's possible to put together a low latency computer for less than £50, whereas with windows, if you want to get anywhere, you have to use a relatively expensive computer. With linuxCNC, the actual output quality of your machine is limited by the parallel port driver, whereas with windows, its more often limited by the software overhead. If you look at the actual performance benchmarks, you'll see that the top end computers are far from expensive: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Latency-Test.

LinuxCNC also boasts superior stability. Windows is known for its tendency to crash for no good reason on mid to low end computers and with mach3 that leaves you in a very tight spot. With LinuxCNC if the computer appears to 'freeze' the machine will still run happily, since it's prioritised over everything including the mouse/keyboard. If there is a timing error it will display a message, so you know something's wrong. No matter how much you disable things in Windows, remove programs or whatever fundamentally Mach3 is not real time so timing errors will exist. The external motion control boards, such as the smoothstepper, can achieve 'smoother' performance and higher speed because they operate in real time. But LinuxCNC does that for free...

The final reason I believe LinuxCNC is far superior is because it's free. By that I don't mean that I don't have to pay for it - I mean the community which developed it has one objective which is making an effective controller. Look at what features come into play when a product is developed properly with the correct objective in mind - full support for helical arcs (allowing threadmilling), rigid tapping and threading with an 'encoder' (1ppr is not an encoder, it's an insult to technology), conditional gcode and many more. As soon as you have to pay for a license, that goes out of the window and the manufacturer's objective of making a decent machine controller becomes secondary to making money and I believe that to be a very important difference. Mach3 already has a large userbase, so there's currently little incentive for Art to make any major improvements as people will still buy it regardless.


And that's why I believe smoothstepper to be a waste of money which would be much better put towards materials for making chips. Don't forget, if you have problems, that's precisely what this forum is for.