What do I need to run LinuxCNC???

[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.

[gatesy]

I'd be looking at using AC servos. I see MESA have a board already configured to output to servo drives which also has encoder feedback as well.

I have a number of old PC's here, so might have to se if I can run the latency test on them and see what I get!

Seems like LCNC is at a bit of a disadvantage here compared to windows based programs like MACH3 etc.

And a bit of a catch22 with what to buy. Not the best situation having to buy something, then test it.

I see Tormach are now using an LCNC based controller, and the Centroid software is Linux based as well. How do these companies get on with what computer to use, or is there software setup different to LCNC?

[gatesy]

Any of these be any good for LCNC?

http://www.intel.co.uk/content/www/u.../overview.html

[gatesy]

Another though with all this talk of latency, etc and suitable motherboards, etc.

How do/did the likes of Fanuc and Heidenhain work? For my use I just want a small PC fitted into the machine, that will just run the cnc control software, a set up the same as Fanuc and Heidenhain.

Is there any latency with Fanuc or Heidenhain controls, and if so anyone know what sort of values?

Not being a particularly computer literate person, if you have a multi core processor, why is it not possible to use one core to just handle the cnc control, and another core to handle the running of the computer?

[JAZZCNC]

How do/did the likes of Fanuc and Heidenhain work? For my use I just want a small PC fitted into the machine, that will just run the cnc control software, a set up the same as Fanuc and Heidenhain.

They use Bespoke Hardware (and Software) designed by them. Pretty much Like Mesa Cards or External Motion control cards for Mach3.
The early ones where based around a crude PC design but mostly just for the I/O interface to access HD etc but there own Bespoke hardware/software does the work.
For instance I've got a HeindenHain Mk3400 Control which under the cover looks just like an old 486PC but that's has far as it goes it's just looks.!! . . . All the Stuff that does the business is on PCI cards and Dedicated daughter Boards in the Main control panel. The PC side does very little other than the display side and Store/pass files to the control.

Don't expect modern Fanuc/Heidenhain performance from Linux Cnc or Mach3 because you won't get it.! . . . . . There is a Reason why they cost ££££ and it's not just profit.
Thats doesn't mean Both Lcnc or Mach can't give them a bloody good chase but you have to realise they will always be behind.!

Having the Same PC/Control Style in a box setup is easy enough with both programs and that's all down to you and how it's gone about.

[Neale]

Been having PC problems over the last couple of days. LinuxCNC PC randomly crashing after an hour or two. This has happened a few times in the past with this motherboard although I thought it was fixed after reseating all components. Long story short - don't rely on motherboard graphics adaptors (the LCNC website discusses this) and use a PCI or similar graphics card. Doesn't have to be very high performance but for some reason this gives much, much better latency figures. Also - make sure you update the BIOS before you start using the machine. I think that this is where my problems came from - old BIOS that didn't properly support a rather later cpu, even though it seemed to run OK.

[Clive S]

This might be interesting for the people that want dual motors to home in Linux https://forum.linuxcnc.org/forum/38-...es-please-test.

[Clive S]

Any of these be any good for LCNC?

http://www.intel.co.uk/content/www/u.../overview.html

In all fairness these questions would be better on the linuxforum I have just seen this that has been recommended http://www.mini-itx.com/store/?c=34#JNF9C-2800 .
No offence Lee

[uli12us]

For Mesa, you need either a PCI(e) slot or a lan connector. Each actual board should run perfectly with it, if it have one of these connectors. Eventually it should run with a parallel port, but nowadays most computers haven't these stoneaged ports.