SWPadnos, new version of grill.py uploaded, now does round, oval, rectangular arrays of holes http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Simple_EMC_G-Code_Generators
skunkworks, opps. maybe the previous line was for you... new version of grill.py uploaded, now does round, oval, rectangular arrays of holes http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Simple_EMC_G-Code_Generators
I think it was for SWPadnos... He was talking about being able to do ovals and such.
what no hex grid!! :)
lerman___ is now known as lerman
lerman___ is now known as lerman
can emc handle a really dumb h-bridge driver?
like, a activation + direction wire for each winding, instead of using logic on the board to combine to step + direction?
oh holy crap.....
has anyone here ever tried to build a servo motor using a small stepper + large dc motor?
steppers dont make servos
yes they do :D
[10:18:40] <Sweeper> http://www.projects-lab.com/?p=401\
[10:18:42] <Sweeper> http://www.projects-lab.com/?p=401
thats a shaft encoder not a stepper used as a motor
but an encoder + dc motor = servo (or servo-isch)
check response, resolution and max speed of that encoder
response is the only issue I see
speed probably depends on how well you isolate the circuit
as you rotate faster generated volts may break the IC's unless protected
I only see one diode
it's the concept that rocks :P
making encoders for $5 from junked floppy drives = win
resolution could be improved with gearing at cost of speed
but your average stepper motor is 1.8 degrees
encoders at that res are freaking expensive
well, except for opticals
with accurate tooth cutting, you could diy an optical for the cost of 2 optointerrups and a slice of plastic
but it's either gonna be really low res or really really big XD
I would worry that a very slow rotation may not trigger the IC and therefore get no output
I shall build a testbed
Sweeper: That device will not properly keep position when the motor stops, because when it does the quadrature goes from any position => 00, violating the quadrature state machine. A similar problem exists when starting to move the shaft. This might be OK if you don't mind a lossy MPG but I don't think you can get reliable positioning this way.
cradek_ is now known as cradek
anyone got any idea about sheetcam?
jepler: mmm, you could cheat tho
I mean, on a dc motor, do you REALLY need quadrature? :P
does the preheat work on the emc post?
Sweeper: you do. Without quadrature you do not know the direction it turns.
alex_mobile: depends. if I hooked the red wire up to positive and the black one to negative, I'm pretty sure I know which direction it turns ;)
that's why I said "cheat"
you were talking about an encoder
nope its ac out from the stepper when used like that
archivist: I mean the drive motor, not the encoding stepper
not if you want to control it as a servo for position control
then it gets turned both ways. And while idle it actually hunts between positions
sanity check: the drive a modern inket uses, which is dc motor + optical encoder, is this a "servo"? because that's about the level of functionality and precision I want
I am suspecting I am using wrong terms :D
yeah, it's probably a servo
Dc motor + encoder = servo
and dc motor + unreliable encoder = broken parts, tooling
the main differnece between a servo and a "regular motor" is that servos are designed to run smoothly at all speeds, generally have lower inertia, and usually are meant to run the same in both directions
aight. well, in that application, and in cnc, I don't see that you really need to know what direction the encoder is going in, esepcially if using a screw drive
yes, you do
if you ever want to reverse travel
you're supplying voltage!
you DO need to know the encoder direction
so it's nit's like...half-open loop
when you cedelerate, the voltage you're trying to drive may be opposite from the movement of the motor
unless you're measuring the motor voltage (which is also hard at very low speed)
err - decelerate :)
oh, like braking?
PID output could be negative relative to the direction the motor is moving
that's how you'll get the motor to move somewhere. how do you expect to use the feedback?
I'm not sure what the acronym means :P
proportional integral derivative - it's a commonly used control method for controlling devices with feedback
wait - you could have a slip clutch on the motor shaft with 2 switches.. Then if the motor was going cw - one of the switches would be closed.. and if it was going ccw - the the other switch would be closed... (maybe I should get a patent)
hey, you know what's a really good, commonly used, solution for this problem? quadrature!
whatever! there has to be another way... ;)
um. yeah. because that's so much easier and less expensive than a $20 encoder ... :)
I wonder if there's a cheap low-cost way to get quadrature independantely
a cheap encoder
learn to scrounge
what is your definition of 'low cost' ?
most ball mice have quadture encoders in them....
this is me spinning a mouse encoder... http://www.electronicsam.com/images/KandT/servostart/Fastermouse.png
[17:40:51] <Guest747> http://www.cnczone.com/forums/showthread.php?p=471206#post471206
Guest747 is now known as skunkworks_
pjmcabbb is now known as pjm
jepler: I'm getting private [grr] email about your/john's solids simulator. it might be nice if one of you would blog about and/or release it.
archivist: I am scrounging! I have lots of scrounged steppers! this is why I liked the idea :P
why not use the steppers for positioning? or are they no good for that?
doing truly cheap servo systems is going to be much harder than steppers.
cradek: it's jmkasunich's code so I'm reluctant to post it to my own blog..
maybe he'll do it. it's a neat hack.
but it might attract a lot of people bothering him, asking why it is what it is, instead of what they want it to be
yes that is inevitable
hi all i just got done whipping up a tiny cnc machine
cool, what kind?
homemade, i had an old u/v axis off a japax edm and i used it for a tiny xy table 1" in y and 1.2" in x hooked a dremel moto tool drill press on top
you can make custom sugar cubes?
i am up in cheeseland at my dads place and built this thing
too bad you didn't bring it to cnc workshop
just finished it about 10 minutes ago
how do i get you some pics?
i got about 75 pics
pick a couple good ones :-)
cradek: these are pretty small steppers :P
version .2.5 rocks.....so does stepconf
unless you've got a cheap way to run 5 steppers in parallel.... :D
Sweeper: did you see my links above?
two pics at imagebin 21869 , 21870
[18:42:42] <jepler> http://imagebin.org/21870 http://imagebin.org/21869
^^ for those who can't pick the right ones out of the list :-P
mdynac_: is Z motorized? I don't see how.
just used what i had laying around
what a wild and crazy 90 degree motor mount
thez motor is sitting behind
nice. first itaught you mean foot, but ist inch
edmnetwork throws these tables away
built like a thank
even have home switches.. nice :)
* anonimasu nods
why not direct-drive? to make it smaller?
what want you manufacture with it?
it was designed to fit in a rectangular box, it is upside down in pic, it actully hung off the z axis with upper flush head attached
it puts taper on the wire
got that mechatronics board off ebay
it uses allegro A3977SED stepper chips, all ic's socketed
guess i'll engrave some stuff now, albiet small stuff....
10µm cubes anyone?
you can set the scale of the AXIS splash screen by changing one number at the top...
hmm nice toy I can see uses for a small machine
it is cool
lerman____ is now known as lerman
skunkworks_: I did now!
I forgot about mouses
skunkworks_: I'm googling now, but iirc, hasn't someone done optical mouse encoders?
it's been tried but they suck in general
[20:56:58] <anonimasu> http://www.hackaday.com/2008/05/16/how-to-scavenge-a-mouse-for-parts/
good night all
no, I don't mean the mouse wheel one
I mean the actual laser+ccd
[21:00:20] <Sweeper> http://www.martijnthe.nl/optimouse/arduino-optical-mouse.html
* alex_joni is off to bed
lerman____ is now known as lerman
Just installed ubuntu 8.04 and emc2 - getting error on starting emc2
I have: /usr/realtime-2.6.24-16-rtai
EMC2 wants: /usr/reattime-2.6-24-19-generic/modules etc.
you have to boot the realtime kernel
pick it on the initial boot menu
Hi Chris. hmm, "initial boot menu?"
yeah it will list the available kernels.
sometimes it is hidden by default so you have to hit escape to see the menu
(which is a bit irritating)
I don't understand where it is though. ubuntu?
yes at the very beginning of the boot, before that colorful ubuntu logo on the splash screen
for a few seconds it will say something like 'press escape for the menu'
Oh. I didn't notice that. So it is part of ubuntu starting up. Right?
boot the kernel that says -rtai
OK. That box is downstairs. I'll go try that. Thanks.
cradek, I picked that, but it isnt there after starting up. Tried it twice. ??
cat /boot/grub/menu.lst | grep realtime
does that show anything?
grep rtai I think
mine still says magma :)
SWPadnos: ever do anything with that openmoko?
actually, I finally got around to updating it (so it could boot) yesterday
it's got a really great screen
yeah 640x480 is how many dpi?
the screen is only 4" or so
it depends on the pixel density of the screen, or so i thought
oh - 3"
It shows kernal is 2.6.24-16-rtai
did you install from the liveCD?
the EMC2 liveCD
What I don't get is when I first installed emc2, I tried axis-sim and it ran fine.
No, I installed ubuntu 7.01, upgraded to 8.04 and installed binary emc2 via net
ok, so it should have pulled in the correct RT kernel debs
In the boot menu, I can see the right one, but I picked that, pressed enter, the OS booted, and it is still the 16 rtai, not 19-generic.
have you ever compiled EMC on this box?
err - wait. when you say it shows you the right one, is it listed in the grub menu as 2.6.24-19, but it boots up and is really 2.6.24-16?
oh. then there's probably a borked symlink in /boot
have you uninstalled any kernel packages?
No I don't think so.
When I booted just before this started, I got an error message at startup - someting about the system corrected a root partition error and requested a restart, then it did. Dang I hate stuff like that that gives you 1.5 seconds to read a whole screen.
I sure appreciate all the folks who work so hard on this stuff, but there are a copule I'd like to shake a bit. ;)
i think you will need a sturdy donkey to navigate the mountain passes
In the terminal error output, it shows EMC2_DIR = ie, nothing. Is that right?
so, just to be double clear what's going on, when you type uname -a what does it say?
just a sec.
2.6.24-19-generic, I'm betting
2.6.24-19-generic #1 SMP date, etc...
that's clearly not correct
perhaps an ubuntu kernel update switched the default around or something?
check in /boot for files named "*2.6.24*rtai*"
It worked before I did anything though. ...
I'm betting that some removal of a kernel package caused a symlink to get pointed back at the default 8.04 kernel
davidf: emc2-sim doesn't need a realtime kernel, that's why it's called sim
I edited the .hal and .ini files.
but you can run the sim/axis config with RT EMC2, it just uses no hardware drivers
fenn, thanks. But, even it doesn't run now.
I get the same error when I try sim.
I did do a ubuntu update between when it worked and when it stopped working. 254 files updated.
you need to look at /boot, to see if you have the correct kernel/SystemMap/initrd
you also need to look at /boot/grub/menu.lst to see what file it's trying to load
when you select the rtai kernel
error: path not found
sorry wrong keyboard!
menu.lst looks right I think...
any missing / incorrectly symlinked entries in /boot?
SWPadnos, in the /boot dir, a ls shows two columns. Are those mappings, or just the way it lists out the dir?
just the way the dir is listed
davidf: "ls" shows things in columns by default; look at "ls /" and you'll see more than 2 columns.
ls -l | grep ^l will show you all symlinks and what they point to
I see System.map-2.6.24-19-generic. Should I look at that file?
or even ls -l /boot/*rtai* :)
on the other keyboard
o fer petes sake.
$ ls -l /boot/vmlinuz*rtai
-rw-r--r-- 1 root root 1911992 2008-06-02 07:58 /boot/vmlinuz-2.6.24-16-rtai
I'm assuming that computer isn't connected to the LAN/net??
any word on the absolute encoders? in terms of can emc support them?
no, never got to that at Fest
ls -l | grep ^l doesnt do anything.
then there are no links (I think - there could be a space before the permissions in ls -l output)
why did we sidetrack into symlinks? (I don't have any symlinks in the /boot on this working system)
what about ls -l /boot/*rtai* ?
because if menu.lst appears "correct", but the wrong kernel boots, that could be a symlink problem
guys, I'm going to put the other box online so I can cut and paste. back in a few.
ok - as long as you can ssh into it, you can look at this kind of stuff
I just disabled the annoying seatbelt alarm in the toyota corolla.. (yes I wear my seatbelt) hold odo button for 20 seconds - fasten seat belt - odo dispay changes to 'b-on' push odo button again to change it to 'b-off'
ls -l /boot/*rtai* shows 4 files...
[23:03:30] <jepler> http://email@example.com/msg07479.html
/boot/config-2.6.24-16-rtai , /boot/initrd.img-2.6.24-16-rtai , /boot/System.map-2.6.24-16-rtai , /boot/vmlinuz-2.6.24-16-rtai.
you rebooted and used the boot menu? which entry did you pick from the list?
you need to choose 2.6.14-16-rtai from the list
Oh. the error output said emc2 quit because It couldnt find etc-19-generic...
now I'm really confused. :)
yes, that error message doesn't sound very helpful
Would it do any good to replace EMC2?
You shouldn't have to replace emc2
you should use the boot menu to choose 2.6.24-16-rtai
the error was confusing because EMC2 was looking in /usr/realtime/`uname -r`/modules
since the wrong kernel had booted, uname -r gave an unintended name
so you think some update set the default kernal to be loaded to the 19-generic huh?
that's my suspicion
if you reboot and select the rtai variant, I'm sure EMC2 will run
yes; if you installed from ubuntu media, you will get their kernel updates and when an updated kernel is installed it becomes the default
yay! sim is running!
you can either change the default entry in menu.lst, or move the one you want to the top of the list. I'm not sure which is ickyest
(users who installed from the linuxcnc.org live cd don't have this problem as far as I know)
so.. why is rtai need for sim? i'm confused
fenn: "sim" is two things
he's not running sim, he's running a configuration from the configs/sim directory
fenn: it's a way to configure emc to not use any realtime facilities *and* it also refers to a set of configuration files that don't require any particular attached hardware
which don't use any RT drivers
but still use the RT code
SWPadnos, is right...
(ie, they don't load or connect to any hardware)
I just chose the sim.ini file.
Now comes the real mess... I have to see if my new .hal and ini will work sometime this year...
I had evrything working well, and my HD crashed, no backups. Lost a lot of stuff...
you've still got ~6 months left
yeah double bummer.
we can rebuild him, better, faster, stronger
it will only cost... a million dollars
Anyway, I want to thank you guys for all the help, and ESPECIALLY evryone responsible for a binary EMC2 pkg for ubuntu!!! I was overjoyed to find that!
yeah, it's a real help
fenn, I am up and running on a free 10 gig HD from a comp. place, and 3 sticks of 128 M ram free, and a thrown-away 400 GHz PII. LOL.
any one here know if you can re-wire a 575 -3 phase motor to be 120 - single phase??
davidf: gratz. i hope to squeeze emc into a 200MHz amd k2 with 64MB ram and some small CF card
i bought a cute little Harding 2nd op lathe from our 5S auction... its still in the van for now..
dmess, To answer literally, Yes, I KNOW for sure I can't.
davidf: 400GHz seems a bit fast tho :)
dmess: 575V not 440?
Ha! yeah, well, whats 3 orders of magnitude give or take?
I ran dapper for a long time on a 400mhz pent II. worked great
yes 575... we were feeding it 600
I had the old emc running on 64MB ram and 1.6 G disk space...
it would be SWEET to EMC this ADD on cross-slide machine..
Hi ray.. you'd know this .. what would it cost to flip a 1/2 HP motor from 3 phase 575v to single phase 120??
$50 for a used replacement motor
maybe less, but then there's shipping ...
1/2 hp is not very big
but this has a very nice sliding mount so you can change speeds ... i dont want to batsardize any of it
motors are dirt cheap on ebay... I was looking awhile ago.
Could you put the mount on a different motor?
I will go out on a limb here and say that you can't rewire a 575V 3-ph motor to run on 120V single phase
if a rewire is a few hundres bucks i'll do it...
dmess just get a VFD
oh, get it rewound - that may be possible, but it'll still be 3-phase
dont wanna go thru the hassle of vfd
oh fff you are talking about rewinding the motors
I think the armature and field coil forms will be different for 3 ph and single.
getting the motor rewound is likely more hassle
and waaaaaay more expensive, I'll bet
vfd is better anyway because you can control the speed
vfd = variable field density??
variable frequency drive
i'll call my cuzin he does that for a living.. a little goverment gob in the Siemens shop should go unnoticed... right??
got to get back to getting this mess back together... Thanks so much you guys.
see you davidf
How much direction changing does this motor do?
it was set up for just 1 direction i believe
Okay that helps.
runs a drill and turns with tool UP in front of the part
Is this motor a common frame mount, c face or what.
i dont believe so... its a hardinge.. made in the USA
and what kind of link between it's shaft and the drill spindle.
I'd try to replace the 575 with a 120 single phase motor.
You'll want one with capacitor start so that you can wire the proper rotation.
but there is 1 thing.... there is a knob on the back of the motor??? i have NO clue what it is or could be for... but will ask the old operator if it varied speed...
Okay. That's a start.
I've not see such a motor from Hardinge.
to what... it being a good 575 motor a or a decent 120 motor??
The 575 suggests to me that you're in CA
lemme see if i can get a phone cam shot BRB
no im in canada
we've been feeding it 600V
Canada is what I meant. I built a couple of process controllers using 575 a few years ago.
I don't see an easy VFD way. You could get a 575 VFD and a step up transformer but that is way UGLY!
[23:58:48] <dmess> http://imagebin.org/index.php
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