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.
Last edited by uli12us; 27-11-2015 at 08:00 PM.
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.
Last edited by Sven; 29-11-2015 at 03:20 PM.
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.!
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.
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?
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?
No offence Lee
Last edited by Clive S; 29-11-2015 at 07:33 PM...Clive
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.
Thanks for the replies, have signed up to the LinuxCNC forum.
LAN connector was the one I was thinking of!
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