#emc | Logs for 2009-05-16

[00:27:53] <JymmmEMC> $0.99 calculator from any gas station?
[02:02:37] <tomp> tomp is now known as tomp4
[04:08:50] <Goslowjimbo> 3 days ago, someone mentioned a bit of software that used the parallel port to make a SPI interface. Does anyone know where to find that? I looked through LinuxCNC.org, and couldn't find anything.
[12:19:28] <tomp> tomp is now known as tomp4
[12:23:34] <tomp4> GoSlowJimbo: get a google search on your browser, click the options or advanced button. tell it to find SPI and tell it to search the irc site www.linuxcnc.org/irc/irc.freenode.net:6667/emc .
[12:23:35] <tomp4>
[12:23:43] <tomp4>  this will find all the irc discussion log entries with SPI.
[12:23:45] <tomp4>  you can also learn to do this from the url field w/o the advanced search form.
[12:23:58] <tomp4> cradek or jepler told us this trick
[12:27:25] <tomp4> SPI site:www.linuxcnc.org/irc/irc.freenode.net:6667/emc
[12:27:55] <tomp4> the above , typed into the google search field, will get you loads of hits
[12:29:36] <tomp4> oh, beware, the search rtns the .txt AND the .rdf variants of the log. the rdf is not nice to read
[13:00:44] <archivist> supply of parts for someone in the states ebay 190307928063
[15:19:05] <pcw> http://www.youtube.com/watch?v=a1ThSi1wbqU&feature=player_embedded
[15:25:21] <jepler> tee hee
[15:29:14] <steves_logging> steves_logging is now known as steve_stallings
[15:44:47] <alSMT> cradek: the problem with axis I had yesterday I think it is this old slow computer of mine if I limit what I am doing and load the part program before I come out of estop on a fresh axis load it works fine, 566 celron ,just letting you know ,thanks for the look see! and the rest of you too!
[16:41:35] <cradek> alSMT: hmm, I think I've seen it freak out on very slow computers. I bet that's part of the cause.
[17:36:21] <steve_stallings> steve_stallings is now known as steves_logging
[18:01:26] <invite> Hi, I have been gathering some infos these days around EMC
[18:01:41] <invite> and started to translate some pages of the website in french
[18:02:05] <invite> Where should I send them or to whom?
[18:05:21] <archivist> send them to the developers mailing list
[18:06:30] <invite> archivist: ok
[19:10:17] <mitchL> hi all
[19:13:46] <BigJohnT> hi
[19:24:42] <mitchL> kind of quiet around here
[19:26:37] <BigJohnT_> yup
[19:31:06] <mitchL> Everybody's EMC must be running flawlessly
[19:31:24] <mitchL> heh heh heh...
[19:33:15] <archivist> mine is undergoing an extension
[19:36:40] <mitchL> I'm currently building a CNC router machine and I'm exploring software options
[19:37:27] <BigJohnT_> stepper or servo ?
[19:40:14] <mitchL> stepper
[19:40:17] <mitchL> for now
[19:40:48] <mitchL> I'm using the JGRO plans from CNCZone
[19:41:02] <BigJohnT_> I use steppers for my plasma cutter
[19:41:24] <archivist> Im adding a 5th stepper today
[19:41:36] <mitchL> I'm figuring this as a first build....
[19:41:50] <BigJohnT_> what kind of drivers?
[19:41:59] <mitchL> As I build I already see changes I want to incorporate into build 2
[19:42:29] <archivist> its fun
[19:43:06] <BigJohnT_> what are you working on archivist ?
[19:43:17] <archivist> 5th axis
[19:43:53] <archivist> original fugly homebrew mill
[19:44:04] <BigJohnT_> cool
[19:44:10] <BigJohnT_> got any pics?
[19:44:14] <mitchL> gotta run... back later
[19:44:16] <archivist> not yet
[19:45:46] <BigJohnT_> BigJohnT_ is now known as BigJohnT
[19:57:18] <colin__> my new EMC project :D
[19:57:20] <colin__> http://img.photobucket.com/albums/v280/rallyslag/5axismill.jpg
[19:58:47] <archivist> that could be fun
[19:58:59] <colin__> should be :)
[20:00:21] <colin__> thinking of using AC servo motors
[20:04:33] <colin__> not decided what to do about the leadscrew backlash yet
[20:04:38] <colin__> it has linear scales on
[20:05:15] <colin__> whether using linear and rotary encoders can work nicely enough together to compensate
[20:06:03] <archivist> cost of fixing the backlash :((
[20:06:39] <archivist> I run my machine in one direction to get round
[20:08:15] <colin__> yeah it will be a pain
[20:09:01] <colin__> tho using the linear encoders should help
[20:10:19] <colin__> doenst have to run any mega fast feedrates anyway
[20:16:21] <colin__> might be worth sorting out the screws for something a bit more accurate tho
[20:16:59] <colin__> doubt they will be cheap due to size tho
[20:17:00] <archivist> you can compensate
[20:17:13] <colin__> yeah
[20:17:21] <colin__> i will try first
[20:18:03] <archivist> but servos and backlash wont be funny
[20:18:32] <anonimasu> linear scales + servos + backslash
[20:19:06] <colin__> yeh
[20:19:54] <anonimasu> I think you better re-think that approach unless you have very good screws
[20:20:15] <anonimasu> or have rotary encoders on the servos(in case it dosent work as you like it)
[20:23:54] <L84Supper> you should be able to compensate for the backlash by profiling the screws. Compare expected position to actual over the length of the screws with your range of loads
[20:24:46] <L84Supper> and speeds
[20:25:30] <colin__> yeah
[20:25:46] <colin__> i think ill check out the screws and see if i can solve the backlash
[20:26:58] <colin__> the motors will have rotary encoders anyway
[20:27:08] <L84Supper> you could always do away with the screws and use linear motors, if you don't mind the cost :)
[20:27:47] <colin__> i think this machine is a bit too big and heavy for linear motors
[20:28:44] <colin__> would probably be better getting some good quality ballscrews and nuts
[20:28:56] <L84Supper> what are the loads?
[20:29:28] <colin__> dont really know exact figures
[20:29:30] <colin__> http://img.photobucket.com/albums/v280/rallyslag/5axismill.jpg
[20:29:33] <colin__> but thats the machine
[20:30:01] <colin__> the y is ok as its counterbalanced, and the z is the spindle in and out
[20:30:18] <colin__> and x doest feel that heavy when manually winding
[20:31:52] <L84Supper> you're not going to move it too fast then
[20:32:44] <colin__> nope
[20:33:35] <colin__> dont need to anyway, spindle speed isnt that high anyway
[20:33:40] <L84Supper> just fyi, linear servo motor example 955N continuous http://www.aerotech.com/products/motors/blmx.html
[20:33:44] <colin__> more for taking slow deep cuts
[20:34:10] <colin__> how does emc like working with linears ?
[20:34:29] <anonimasu> L84Supper: cute, but what do they cost?
[20:35:11] <anonimasu> ^_^
[20:35:31] <L84Supper> depends of your pocketbook :)
[20:35:48] <L84Supper> sp of/on
[20:36:26] <colin__> i did think about building a machine a while back using a granite table
[20:36:34] <colin__> using airbearings and a linear motor
[20:38:02] <L84Supper> http://cgi.ebay.com/AEROTECH-ABL20060-LINEAR-AIR-BEARING-STAGE-MOTOR-WOW_W0QQitemZ360151055350QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item53daacfbf6&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A1318|301%3A1|293%3A2|294%3A50
[20:38:21] <L84Supper> light duty
[20:38:49] <anonimasu> hm, for 5000 you can buy a used machine already made..
[20:39:16] <archivist> they dont look ok for machine tool work
[20:39:17] <L84Supper> yeah, you don't need 1 micron res
[20:39:44] <colin__> yeah a bit much
[20:40:24] <L84Supper> I bet you can profile your screws down to a few microns
[20:40:41] <archivist> I did score a new proper ballscrew on ebay
[20:41:03] <colin__> http://www.newwayairbearings.com/Dovetail-Air-Slides
[20:41:15] <L84Supper> recalibrate the screws every month or so
[20:43:53] <colin__> probably not neccesary tho
[20:44:22] <colin__> i do think using linear encoders along with the rotarys on a fairly tight system should be accurate enough
[20:45:02] <L84Supper> I'm using EMC2 in the design of a new digital web press, servos, tension control, head positioning etc.
[20:45:50] <cradek> colin__: http://www.jmkasunich.com/cgi-bin/blosxom/shoptask/wichita-trip-02-20-08.html
[20:46:19] <colin__> cradek, yeah iv seen that thanks :)
[20:46:45] <cradek> ok, just checking, that was one successful experiment with dual feedback
[20:48:14] <L84Supper> the linear encoders will give to actual position, and your rotary encoders will give you what the motors actually did
[20:48:28] <L84Supper> sp to/you
[20:49:16] <colin__> would it be better to setup the servos with a driver that handles the encoder to the motor itself
[20:49:50] <colin__> then have emc have backlash settings and use the linears as a check the ferror
[20:50:09] <L84Supper> exactly, since you have both you'll be able to check
[20:51:26] <colin__> hmm could work best as the motor then wont be hunting each side of the backlash to make the linears move
[20:52:37] <L84Supper> if you rely on the rotary encoders only and the lash changes you won't find out until you check your parts
[20:52:46] <colin__> yeh
[20:52:54] <colin__> well if i use a drive that takes step/dir
[20:53:01] <colin__> emc can be setup just like a stepper system
[20:53:11] <colin__> but with the linears to check the error
[20:53:27] <colin__> and just set the backlash in emc
[20:55:26] <colin__> least then it would stop things if the error was too high
[20:55:35] <L84Supper> yes
[20:56:46] <colin__> excellent :)
[20:58:22] <colin__> i may well still see about new ball screws
[20:58:25] <colin__> depends on cost
[20:58:38] <colin__> least if i can rig it to work for now ill be happy
[20:59:10] <L84Supper> I don't use screws much myself since we tend to be working with things that move all the time, we'd wear out most screws in days or weeks
[21:00:43] <colin__> i guess it depends on speed and load aswell
[21:01:14] <colin__> with decent ground ballscrews i bet this machine could run for 20yrs without problems
[21:04:58] <L84Supper> yeah, your feeds rates are probably in the fractions of an inch per second
[21:06:25] <colin__> yeah
[21:06:30] <colin__> probably about 2000mm/min
[21:06:56] <colin__> at most
[21:09:12] <L84Supper> I'm working on some now that move at 1000mm/sec with accel and decell at 1-2G
[21:09:34] <colin__> thats pretty quick
[21:11:20] <colin__> id love to build a little high speed mill one day
[21:13:46] <L84Supper> gantry with only 10Kg load, +/- 50 micron repeatability
[21:14:33] <colin__> :)
[21:16:08] <colin__> think most of my tooling has a higher run out than that lol
[21:17:27] <L84Supper> yeah, these are >$100K with a 1.5m x 3m bed
[21:19:14] <colin__> what are they for ?
[21:19:45] <L84Supper> inkjet printers
[21:21:19] <L84Supper> mostly for printing electronics, solar cells, OLED displays, etc.
[21:21:27] <colin__> ah i see
[21:22:42] <colin__> think my next project is robotic arms
[21:22:42] <colin__> already aquired a cheap little one with ac servo motors
[21:22:42] <colin__> gonna test out the kine on that, then look at getting a big ABB bot
[21:23:06] <L84Supper> fun stuff
[21:24:13] <L84Supper> ABB is pretty free with their specs and manuals
[21:24:27] <L84Supper> just not for their software
[21:25:28] <colin__> what kind of bearings do they use ?
[21:25:28] <colin__> in your printers
[21:25:40] <L84Supper> air and linear
[21:26:06] <L84Supper> well, air and magnetic
[21:26:24] <colin__> ah cool
[21:26:30] <colin__> do air bearings work well at high speed then ?
[21:27:22] <L84Supper> for linear at 2 meters/sec and rotary at 22,000 rpm
[21:28:00] <L84Supper> we use the rotary air bearings for laser scanners
[21:28:33] <colin__> thats pretty quick
[21:28:46] <colin__> how do they handle load?
[21:30:21] <L84Supper> works for us, iirc the rotary handles a few Kg at 22K/rpm
[21:32:10] <colin__> i bet encoder counting must be an issue at your feedrates ?
[21:32:31] <L84Supper> not with an fpga
[21:32:55] <colin__> ah
[21:33:00] <L84Supper> we can count and process faster than we could ever move
[21:33:18] <colin__> i have some mesa boards for my mills
[21:33:28] <colin__> not sure what the max encoder count is on them tho
[21:33:55] <L84Supper> if you count in hardware >100MHz
[21:34:47] <L84Supper> iirc the fpga's in the Mesa can probably handle inputs to 200MHz
[21:34:58] <colin__> ah
[21:35:16] <colin__> what sort of mhz are the fpa you use?
[21:36:37] <L84Supper> the <$100 Altera or Xilinx are 200Mhz
[21:37:19] <colin__> ah right
[21:37:31] <colin__> so the mesa is fairly capable aswell then
[21:38:01] <L84Supper> http://flash-plaice.wikispaces.com/ here' a logic analyzer we started working on
[21:40:33] <colin__> looks impressive
[21:40:36] <colin__> whatever it does :)
[21:41:42] <jepler> sounds similar to http://www.sump.org/projects/analyzer/
[21:42:07] <L84Supper> captures digital signals, puts them up on the screen for analysis
[21:42:16] <jepler> (that one's not flash programmer or ice though)
[21:42:45] <L84Supper> we started adding on to the sump project
[21:43:01] <jepler> sounds like a very sensible approach to me
[21:43:51] <L84Supper> was mainly for emulating flash in circuit for open source bios development
[21:44:17] <L84Supper> coreboot for x86 and uboot for risc
[21:45:17] <jepler> sounds neat
[21:45:53] <jepler> I have an s3board with sump.org's la installed on it, but I don't use it as much as I expected to
[21:46:11] <L84Supper> trying to get to the point of a complete open source machine controller
[21:47:07] <L84Supper> firmware, OS and applications
[21:47:31] <colin__> will it run emc :P
[21:48:01] <L84Supper> I just don't get the wide use of XP in machine control, I always ask where the reset button is for when it hangs
[21:48:39] <L84Supper> "XP for killer robots"
[21:50:34] <L84Supper> we have EMC running on some mini-itx VIA boards C7 +cn700 chipset
[21:51:00] <colin__> ah
[21:51:12] <colin__> tbh most of my emc systems are just old hardware iv found laying around
[21:51:33] <L84Supper> benchmarking now to see what we can really do, coreboot + Linux + EMC
[21:52:26] <L84Supper> ~$120 for 1.5GHz C7 + 1GB DDR2, unichrome graphics are a bit of a pain
[21:53:16] <L84Supper> http://www.via.com.tw/en/products/mainboards/motherboards.jsp?motherboard_id=490
[21:53:43] <colin__> why unichrome?
[21:54:02] <L84Supper> unichrome is integrated into the northbridge
[21:54:44] <L84Supper> runs the speed of a decent ATI gpu from 6 years ago
[21:55:53] <L84Supper> we will try some AMD 690/600 as well in mini-itx
[21:56:02] <colin__> ah
[21:56:08] <colin__> so whats the advantage of coreboot?
[21:57:13] <L84Supper> open source BIOS, fast boots , 5 sec from power on to login
[21:58:29] <L84Supper> we should be in the 2-3 sec. max range with a bit more tweaking to Debian
[21:58:59] <colin__> that must be pretty stripped down almose useless kernel tho ?
[21:59:42] <colin__> or can it load up X and emc pretty quick aswell ?
[22:00:16] <L84Supper> yes, 5 sec with X, power-on to X login
[22:01:28] <colin__> thats quick
[22:01:39] <colin__> so where does it load it all from ?
[22:02:02] <L84Supper> you can have a kernel in flash along with firmware
[22:02:59] <colin__> then just load X and whatever from a drive?
[22:03:31] <L84Supper> yes, you have to wait for the drive to spin up
[22:03:53] <L84Supper> kexec lets you swap kernels without reboot as well
[22:04:33] <colin__> could probably just load the rest from a usb key pretty quickly then ?
[22:05:16] <L84Supper> yes, ~1 sec for coreboot + kernel in flash, then EHCI in kernel to load from Flash drive
[22:05:51] <L84Supper> Phoenix just started copying us again, kernel + BIOS in flash
[22:07:13] <colin__> ah cool
[22:07:29] <L84Supper> http://linux.slashdot.org/article.pl?sid=09/05/14/2254252&from=rss
[22:08:20] <L84Supper> http://www.technologyreview.com/computing/22643/
[22:09:04] <colin__> think for what i have planned
[22:09:17] <colin__> i might just setup emc in dsl or puppy linux
[22:09:38] <L84Supper> we are doing it with debian
[22:10:04] <L84Supper> somebody here was working with Arch
[22:12:29] <colin__> cool
[22:12:58] <L84Supper> was working on getting EMC on Ubuntu 9.04
[22:13:07] <colin__> i am hoping to build emc into a plug and go system for something
[22:13:18] <colin__> so keeping it minimal is best
[22:13:37] <L84Supper> rtai_shm wasn't found or something error
[22:14:40] <L84Supper> Ubuntu , ugh
[22:15:10] <colin__> that C7 mini itx board looks really nice
[22:15:47] <L84Supper> if VIA can stay solvent
[22:16:18] <L84Supper> http://wwwd.amd.com/catalog/salescat.nsf/doclookupweb/C535EA5BBC2201BC862572BB002ECA24?OpenDocument&id=WinMate+Communication+INC.+~A270+Mini-ITX+Industrial+Motherboard
[22:17:30] <L84Supper> supports dual core X2 with 690/600 chipset
[22:19:57] <L84Supper> http://wwwd.amd.com/catalog/SalesCat.nsf/doclookupweb/5B08DE8F63A45F3F862572BC001ED692?OpenDocument&id=IEI+Technology+Corp.~KINO-690S1
[22:20:28] <colin__> the little C7 board is probably more than enough tho
[22:20:34] <L84Supper> http://wwwd.amd.com/catalog/SalesCat.nsf/doclookupweb/061E74F713F701688625730D00106818?OpenDocument&id=MSI~Fuzzy+RS690T
[22:20:58] <L84Supper> sure, but incase you need more cpu or graphics, the 690/600 is supported by coreboot
[22:22:43] <colin__> colour gfx would be nice
[22:23:41] <L84Supper> we did some flight simulator game to run ok on the VIA vb7001
[22:24:29] <L84Supper> DVD playback is only on 5% of the cpu with tweaks to VLC
[22:24:50] <colin__> well i only want it to run emc
[22:25:01] <colin__> attach via a usb mesa board
[22:25:27] <L84Supper> the driver devs at VIA don't know Linux well
[22:26:01] <L84Supper> it does have a single PCI slot but there is a dual PCI riser with extra INT's
[22:27:01] <L84Supper> EMC over USB is limited to the latency of the isochronus transfers
[22:27:03] <colin__> yeah
[22:27:42] <L84Supper> going to see how fast we can get it going
[22:28:28] <L84Supper> you might not be able to control a high speed spindle, but it may work well enough for many apps
[22:28:38] <colin__> well i need to control a minimum of 6 motors
[22:29:05] <colin__> with encoder feedback
[22:30:29] <L84Supper> your rates may be slow enough
[22:30:54] <colin__> this is for a robotic arm
[22:31:08] <colin__> so still not going to be super fast compared to your application
[22:31:18] <L84Supper> plus if you are using a small distro with only EMC running, no backgound services or sharing of the USB
[22:33:59] <L84Supper> according to the Linux kernel doc "Log2 of default interrupt delay, in microframes. The default
[22:33:59] <L84Supper> 107value is 0, indicating 1 microframe (125 usec). Maximum value
[22:33:59] <L84Supper> 108is 6, indicating 2^6 = 64 microframes. This controls how often
[22:33:59] <L84Supper> 109the EHCI controller can issue interrupts.
[22:33:59] <L84Supper> "
[22:34:58] <colin__> meaning what ?
[22:36:37] <L84Supper> EMC over EHCI USB, 125 usec would be the min. time between interrupts
[22:36:59] <L84Supper> if you need anything services faster , it won't work
[22:37:09] <L84Supper> serviced even
[22:37:38] <colin__> oh right
[22:37:53] <colin__> would i be better with a pci mesa board ?
[22:38:09] <L84Supper> yes, PCI irq's are faster
[22:38:57] <L84Supper> 125 usec = 8000 irq's per second
[22:39:40] <colin__> ok
[22:39:40] <Skullworks> USB = Ugly sluggish bus
[22:41:36] <cradek> the neat thing about choosing a pci or epp board over a usb solution is that it exists
[22:41:59] <alex_joni> and there's a driver for it
[22:42:04] <alex_joni> and a maintainer
[22:42:18] <alex_joni> and a company behind the boards
[22:42:50] <L84Supper> yeah, we looked at a usb driver for this, no real need so far
[22:42:55] <cradek> also, it works
[22:43:09] <cradek> can't think of any drawbacks actually :-)
[22:43:11] <colin__> pci is fine :)
[22:43:26] <alex_joni> cradek: maybe some might say it's uncool :P
[22:43:38] <alex_joni> less plug& play
[22:43:45] <alex_joni> although for a mill that's rubbish
[22:44:21] <cradek> meh
[22:44:56] <L84Supper> maybe there is a need now for some PCIe fpga boards for EMC
[22:45:14] <maddash> |oi ,<--- which wire is 'hot'?
[22:45:30] <maddash> | i
[22:45:30] <mshaver> cradek: Hey there's another guy named cradek over on the #beagle channel!
[22:45:32] <cradek> I think mesa is working on pcie boards
[22:45:35] <maddash> | i
[22:45:39] <maddash> o
[22:45:40] <cradek> mshaver: funny that
[22:45:56] <Skullworks> Alex, did anyone get a pre-compiled 2.3.0 sim made yet - I'm rpl my laptop SSD and figured I'd use the latest if its available?
[22:46:00] <cradek> I hear he's a big jerk
[22:46:13] <alex_joni> Skullworks: sim is there for 2.3.0
[22:46:15] <cradek> Skullworks: it's in the repositories
[22:47:02] <cradek> wow, the user map is getting fuller
[22:47:17] <alex_joni> Skullworks: http://linuxcnc.org/hardy/dists/hardy/emc2.3-sim/
[22:47:21] <Skullworks> cool - wiki still only listed the 2.8 which I had - I'll update the Wiki after I get it successfully installed.
[22:47:38] <alex_joni> Skullworks: 2.2.8 I hope ;)
[22:47:49] <Skullworks> yes
[22:48:19] <alex_joni> cradek: yeah, but also spammier some times
[22:48:31] <Skullworks> running on 8.10 works for tk but not axis
[22:49:00] <maddash> arghh
[22:49:11] <cradek> alex_joni: oh do you have to keep cleaning it up?
[22:49:15] <Skullworks> but for testing errors in the G-code it does just fine
[22:49:19] <alex_joni> I do it from time to time
[22:49:31] <maddash> if i want to electrocute myself with a regular 120VAC outlet in the USA, do i have to connect myself to both vertical pins?
[22:49:34] <alex_joni> I don't really understand why spammers go through the extra trouble
[22:49:45] <alex_joni> they need a valid email, and verify the new account, etc
[22:49:56] <cradek> maddash: no, one will do
[22:50:02] <alex_joni> then they appear on the map, with a link to the profile, where they have a link to some pammy page
[22:50:07] <cradek> maddash: but I suggest you try it both ways to be sure
[22:50:10] <alex_joni> s/pammy/spammy/
[22:50:14] <maddash> cradek: which one?
[22:50:37] <alex_joni> maddash: either you connect to both
[22:50:43] <alex_joni> or you connect to gnd and only one
[22:50:43] <cradek> the small one may work better
[22:50:52] <alex_joni> but then you have a 50%-50% chance
[22:51:05] <Skullworks> a backfeeding neutral can really wake you up too.
[22:51:14] <maddash> alex_joni: but bottom line is that i have to touch at least two of the three (two vertical, one circle) pins, right?
[22:51:27] <maddash> wait a second
[22:51:28] <alex_joni> no, sometimes it's enough to touch one
[22:51:39] <alex_joni> if gnd closes through you and where you are standing
[22:51:41] <Skullworks> Depends on how well you are grounded
[22:52:03] <alex_joni> if you have rubber shoes, then touching any one should be fairly non-deadly
[22:52:08] <maddash> if i"m sitting in a tub full of water, which wire do I touch? the larger?
[22:52:23] <alex_joni> maddash: probably any is just as fine :D
[22:52:41] <alex_joni> take a switch that goes to a lightbulb, then it's surely fine whatever you touch
[22:53:03] <maddash> how can that be? i wouldn't be closing the circuit
[22:53:04] <alex_joni> you'll end up under water anyway
[22:53:19] <alex_joni> if you are in water you are closing it
[22:53:28] <alex_joni> water is connected to gnd through the drains
[22:53:45] <maddash> right, but the generator at the power plant isn't connected to the ground
[22:54:00] <L84Supper> what about PVC waste lines?
[22:54:14] <alex_joni> L84Supper: there it might be different
[22:54:15] <mshaver> maddash: actually, if it's a fairly new outlet, and wired correctly, the shorter of the two vertical slots is "line", the taller one is "neutral" which is connected to "ground" (PE to the EU folks) in the fuse box.
[22:54:24] <maddash> i.e., the smaller pin in my AC outlet is connected to the "-" end of the generator, and the larger pin is connected to the + end of the generator
[22:54:50] <alex_joni> usually neutral and gnd (PE) have a very similar potential
[22:55:31] <alex_joni> if you have a good PE connection, and no differential breaker then you can run some appliances on line and gnd/PE
[22:56:32] <alex_joni> mshaver: it's quite common in factories around here to wire neutral and PE together, and only use lines for "line's"
[22:56:40] <alex_joni> err.. wires
[22:56:45] <mshaver> in the US there are two "line" wires, each is 120Vac away from ground, and they are 180 degrees out of phase, thus there is 240Vac from line to line.
[22:57:18] <maddash> mshaver: exactly! so since I live in NY, I'd have to touch both line wires to off myself, right?
[22:57:18] <alex_joni> we have usually neutral, 3 * line and PE
[22:57:21] <mshaver> together at the fuse box, or do they use PE to return load current as well
[22:57:51] <alex_joni> maddash: anything about 50V or so can be deadly
[22:58:06] <L84Supper> i have 120/208 wye
[22:58:17] <alex_joni> if you stick an electrode inside your skin, you can die by 9V or less
[22:58:42] <alex_joni> mshaver: so you use both lines in a house installation?
[22:58:46] <alex_joni> to separate the load?
[22:58:54] <maddash> brb, going to try this out
[22:59:11] <alex_joni> maddash: use a voltmeter first
[22:59:24] <mshaver> maddash: not really. If you touch the short slot (line) and you are also touching a metal plumbing fixture that is grounded (typical), then the "line" current will return via the grounded plumbing.
[22:59:43] <tomp> tomp is now known as tomp4
[23:00:21] <alex_joni> also, almost all electrical devices with a metal frame are connected to PW
[23:00:22] <alex_joni> PE
[23:00:32] <alex_joni> so touching that and a line should be just as bad
[23:01:33] <L84Supper> if your power cord is three prong and your outlet is only two prong, should I clip off the ground pin or rewire the house?
[23:01:34] <mshaver> alex_joni: yes, the input from the power company to a house is a center tapped transformer secondary. The center tap is called neutral and is tied to earth ground via a rod driven into the ground.
[23:01:47] <maddash> OW.
[23:01:59] <mshaver> the secondary voltage is about 230Vac
[23:02:26] <mshaver> although Ive seen 219 and 247
[23:04:59] <mshaver> Everywhere else in the world (except Liberia I think) you have 220Vac and one side of this circuit is attached to earth somewhere, sometimes at the building it's entering and sometimes at the power station as I understand it.
[23:05:29] <alex_joni> it's 230VAC in europe now
[23:05:50] <alex_joni> and 400V for 3-phase, instead of 380V a couple years ago
[23:06:59] <mshaver> So, I see equipment (single phase) with the wires labeled L, N, and PE. The problem comes in when we hook it up and the "N" wire is 120Vac away from PE.
[23:07:40] <tomp4> what is l to pe?
[23:07:54] <mshaver> 120
[23:08:07] <tomp4> then L to N is 0 or 240?
[23:08:13] <mshaver> 240
[23:08:16] <tomp4> ew
[23:08:17] <mshaver> sorry
[23:08:53] <mshaver> l to n, if it's a 240V machine from the EU is 240
[23:09:07] <tomp4> k
[23:09:29] <mshaver> US built machines can have 4 wires in a single phase setup: L1, L2, N, and GND(PE)
[23:09:56] <tomp4> physical earth, yep
[23:11:09] <mshaver> One advantage is that since L1 and L2 are 180 degrees out of phase you can return all the 120 load current from both L1 and L2 via a single neutral wire.
[23:16:11] <alex_joni> mshaver: yeah, but on equipment with L,N and PE, it should be safe to connect things where N and PE are different
[23:16:24] <alex_joni> PE only goes to the exterior of the equipment
[23:16:35] <alex_joni> and N is for neutral
[23:16:42] <alex_joni> * alex_joni heads to bed though
[23:16:47] <alex_joni> good night all
[23:16:58] <tomp4> gnite
[23:16:59] <mshaver> night!
[23:17:22] <mshaver> alex_joni: true, it's more of a labeling thing
[23:20:32] <tomp4> rockwell/allen bradley ~(not aquote) neutral is a reference point, not meant to carry any current except mistakes. gnd is a current path fro when insulation fails http://www.ab.com/drives/techpapers/rfignds.htm
[23:21:07] <Skullworks> nifty - using the 2.3-sim.deb Axis works in 8.10 - sim 2.2.8 Axis didn't play well with the updated file versions.
[23:26:17] <tomp4> this neutral ground has lotsa opinions, another src sez neutral always carry current, and gnd is a safety return that fuses can use ( fuses from line to gnd??!!) http://www.askmehelpdesk.com/electrical-lighting/ground-bar-vs-neutral-bar-111142.html
[23:27:21] <archivist> gnd is safety and fault path it must remain intact to blow fuses
[23:28:22] <archivist> UK specs for gnd wire has become insane
[23:30:09] <tomp4> If neutral and Gnd are connected... then you can check insulation by... "For measuring an insulating fault, you loose the screw and measure the resistance between N and PE. Normally it should be very high, several Mohms or infinite." (get a 'megger' to check this )
[23:30:31] <tomp4> the screw refered too connects gnd and neutral
[23:30:54] <tomp4> dinner, bye for now
[23:31:00] <tomp4> part
[23:31:06] <tomp4> hah!
[23:43:39] <robin_sz> is this thing on?
[23:50:55] <L84Supper> :)
[23:51:00] <robin_sz> ah good
[23:59:57] <Skullworks> This will turn some heads - running sim on my EeePC - The ultimate in backplot software - Testing you G-Code on the real control app.