The Shop > Software Tools
Attempt at LinuxCNC (formerly EMC)
awemawson:
Does it possibly hold two different values, 'zero origin', and 'home' rather like doing an origin shift on some systems ?
Joules:
Yep,
Andrew is pretty much right... As to homing and limit switches !!! Whats the point, on my router the switches are magnetic reed attached with doubles sided tape, far from accurate and to be honest I did't even notice the magnets had fell off the tape as I never use them. Since in CAD I always use a 0,0,0 origin for my drawings I carry that through to the router and have the centre of the bed 0,0,0. My machine has a 1000mm x 600mm working area (plus 3mm clearance). So if I do set things up I move the gantry to within 1.5mm of one end ZERO my position, then give it a positive or negative 300/500 to move it to the centre and re ZERO the settings using the manual control panel, select X,Y or Z and press the Home axis, that sets your local home to zero. Note the target marks next to your XYZ co-ordinates. LinuxCNC won't progress if they are not set.
Since I use odd bits of material I tend to zero on the work piece than try to set the material to a bed location that way I can just zero in the middle then run the gantry round to make sure I have enough room for the job. Z is always zero to the stock surface so no confusion over that.
You input G0 commands in the MDI screen (F5) to move around. Here I have a wireless mouse and keyboard that are used right next to the work for setting up. Must make a control pendant at some point in time.
vtsteam:
Joules, that's pretty much the same way I used to do it in TurboCNC. Also drawing from 0,0,0.
I shouldn't have bothered trying to use the limit switches as home switches (one of the options in LinuxCNC). Last night I just changed the configuration to plain limit switches and no home switches, and things seemed to work -- I was able to home. where I wanted to. I ran the laptop here in the house -- so could only simulate a cut, but will hook it to the mill in about an hour or so nd try cutting a part (out of foam sheet first).
Thanks for your suggestions and help, Joules. :beer:
I'd still like to understand what I was doing wrong in setting a home position with the combined limit and home switch option, but at least it all seems to be workable now without home switches enabled.
And it's odd -- maybe it's just because I was used to it, but I like the old DOS TurboCNC interface better than LinuxCNC's. In TurboCNC Hitting f8 put you into a jog screen where you could do all kinds of stuff, including zeroing axes, homing, jogging, overriding limits, saving position, etc, so just one screen and multiple keys for doing things manually. Then hit ESC and back to the main panel for running and editing programs, setting configurations, etc.
I really miss the "Zero all axes" button in TCNC.
The Home button in LCNC (at least with the home switches enabled) only seems to move an axis to whatever pre-set Home there is. It doesn't set a new home. There doesn't seem to be a button to set a new Home. And I'm unclear about what "unhoming" means. There's a dropdown option for that.
I especially don't like having to go to a separate program to make a configuration change (like setting a Home position), and since it's a wizard, you have to wade through a bunch of questions to get to the parameter screen you really want to change. Change it, and then scroll through more screens to save it eventually, close the program and re-open the CNC program. Long process for just changing a single config parameter while testing.
I'm sure that there must be other quicker ways to do this -- I just don't know them yet.
I'm reading the full user manual now, and it probably will make more of the operation clear, than the Getting Started manual.
On the plus side, the writing style is excellent, and it's neat to find that there are many variations to the GUI available. The program now seems to run well on my ancient laptop, and I really do appreciate the graphic display of the cut in progress in 3D perspective -- something TurboCNC naturally couldn't do. There's also a nice program in LCNC for determining your max speed and max acceleration possible. And with a lookahead buffer, the average speed should be much closer to the specified feed speed -- which is why I am making the switch in the first place.
Biggest complaint so far:
I really hate Ubuntu on this laptop. It's slow as molasses in January!
Please, please somebody, recompile this for Puppy Linux....... :)
Joules:
Have you tried the live install of 2.6 based on Debian Wheezy... I'm very pleased with it and moved away from Ubuntu. It's stable and so far updates haven't caused any issues. Dos TurboCNC was packaged with this machine, but at the time I was using Linux anyway so went straight for EMC2 and the steep learning curve. Once things got working on a ratty PC I bought a new box to dedicate to the router, its all networked to my central storage so transferring things from the CAD station to the cnc router are across the network we have here.
vtsteam:
Joules, nope didn't try the Debian version because it's even larger -- 1.1 Gig -- about double the size of even Ubuntu in fact-- won't even fit on an install CD. And I'm not sure I can boot from a DVD on this laptop.
I'm certain I can't boot from a thumb drive, which is the other claimed option.
I really don't see why we need a modern bloated Linux OS bundled with browser, mail, chat, full open office suite, etc to run a CNC program on only a dedicated CNC box. This should all be easily do-able on 10 year old single proc. computers with parallel ports. Stuff going to the dump or hidden in closets is perfectly capable of doing this kind of task quite well.
The problemcomes from the developers choosing a large slow Linux OS's to compile it on, so older computers can't easily load the later versions, and are hampered in speed by the OS size and proc requirements. Currently:
Ubuntu 8.04 w/CNCLinux takes up 680 megabytes on CD.
Debian WCNCLinux takes up 1.1 Gig
By contrast, Puppy Linux loaded with 50 apps takes up a mere 100 megs on CD, and will run maybe 5 times as fast, for normal OS tasks. LinuxCNC could easily fit with it on a CD with plenty of room to spare.
Nothing wrong with LinuxCNC itself -- I just got finished cutting a foam test panel on the Thinkpad, and it works fine so far. I have to tweak my G-code a little, but that has nothing to do with LinuxCNC. LinuxCNC itself runs fine on old machines.
It's when I drop out of the CNC program into the OS that everything is painful. It takes an irritating amount of time to open the Stepconf program, or LinuxCNC itself, or load a part file into a directory -- just normal OS operations. Sometimes I think the computer has stalled, but waiting another minute reveals it's just running slow.
By comparison, I can boot into Puppy Linux on this same computer, and OS operations and apps run like it's a dual proc modern computer. Fast as you click on something it opens. No wait.
Well anyway enough of that subject. The good news is LinuxCNC works well on a very old dumpster computer -- even a laptop.
I'll probably try cutting aluminum today when the G-code looks good. :thumbup: :beer:
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