What do I need to run LinuxCNC???

[gatesy]

I'd be looking at buying a PC to install into the machine just to run Linuxcnc, nothing else.

So any recommendations, or where I can find PC recommendations would be welcomed

[uli12us]

What are you want with PC a complete PC or only a motherboard. If you want a complete PC then you can use nearly any model from the last 3 years, they all should be fast enough for this purpose.
If you want a motherboard, then a fanless board with standard Ramboards is good. The AsrockASR Q1900B-ITX or any similiar board is more than enough. A atom board with 2*1,86GHz is good as well. If you prefer AMD, than thats no problem, the linux version you need can run on both platforms.

[z3t4]

... or where I can find PC recommendations ...

Hi Gatesy

Essentially you should be looking for a PC or motherboard with small latency and jitter numbers.
uli12us has given you some answers, but have a look here and at part I of the FAQ ('The Latency Problem') for some of the working out.

HTH

[gatesy]

I was looking at something along these lines, a fan less industrial PC

http://www.aliexpress.com/wholesale?...+industrial+pc

Ok thanks will have a look

[gatesy]

Found this one

Single core processor, but it looks like they can be built to what spec you want

http://www.aliexpress.com/item/XCY-A...rchweb201560_8

[uli12us]

Why do you want a complete computer, for much less money you get a COB Board and can add parts you like. Faster or bigger ram, SSD instead of HDD. I recommend Boards, in which you can use standard Ram chips, instead of the SO-DIMM. The board is inside your electric cabinet and don't need some extra housing. Except you want to mount the Computer behind a touchscreen Monitor, you don,t need an IPC. But single core is enogh for LCNC, it can't use a dual or Quad Core.
I use this, but must wait until I have enough money to work an my machines. The Mesa board run with this, without problems. BTW, you should have a LAN Port.


http://www.asrock.com/mb/Intel/Q1900M/index.de.asp

[Sven]

Do not just go ahead with buying new parts to use for LinC without knowing they are fit for purpose.

The single most important thing to run LinC well is the so called latency, for which a test is included with the Linux cnc live cd.

I sort of collect older pc's and test them for this. If the numbers are good, then I keep it.

I now run a pentium 4 2ghz I bought new maybe in 2005 or something.
Ram, ssd and that modern stuff is pretty much irrelevant for the cnc part, but it may be nice for smooth operation for the operator.

With modern boards latency can vary a lot so if you can not test it, or know from others latency is good, do not buy it.

When I started I ran LinC directly from the parallel port.
When I added a 4th axis that did not work so I had to add a BOB.

Once you have the pc, you can just try to run it, if it does not work well, add bob, or add mesa.

[JAZZCNC]

I'm not a Lcnc user but I'll just throw this question to those that have posted so far. !. . Do most of you run Steppers or Servos.?

Servo's require much higher frequency than Steppers so I would be speaking or listening to those using Servo's because it may well change the Game regards PP and PC.!

[Neale]

Good point, Jazz. I use steppers, with a BoB and a PCI parallel port adaptor card. My motherboard, bought about 18 months ago, is an MSI A55M-E33 with an AMD processor and 8G RAM. I see from the place I bought it that that MB is no longer available, which just about sums up the problem with PCs and, particularly, motherboards - I've never seen a list of "suitable" MBs that actually has anything on it that I can buy! I did the usual LCNC latency test, and have ended up with a kernel speed of 28KHz (from memory) but my router is not that fast and fastest rapid feed only needs about 8KHz, so there's plenty of headroom.

I wasn't aware that LCNC could support servo encoder feedback directly (but I haven't needed to, so I've never looked for this feature). That would certainly put up the required kernel speed; on the other hand, the OP was talking about a mill where speeds are much lower than a router, so maybe it would be OK. All the same, if you are going to the lengths of using servos and the complications of feeding back encoder output to the motion controller as opposed to a self-contained servo controller, then I'm sure that it would be worth going to the cost of an external motion control card that can guarantee performance.

Doing some simple back-of-envelope calculations for a sanity check - my current router uses a 1.5mm pitch leadscrew (best Screwfix stainless threaded rod and everything...) and 800microstep/rev. 900mm/min max feed (at which point the leadscrew is not quite whipping too much) needs a pulse rate of 8KHz. Go to a 5mm pitch ballscrew and that would give 3m/min rapids with same pulse rate; LCNC tells me that it could run at least twice the current pulse rate so that would give 6m/min rapids and still not be pushing the limits too much. So, with steppers a cheap modern MB running LCNC would comfortably handle a typical "hobby use" router. I'm going to a CSMIO-IP/M for the next machine, but more for peace of mind and general electrical/EMI proofing than real need. Servos - different story.