#emc | Logs for 2009-07-21

[00:49:43] <Valen> heh somebody at mesa has a sense of humor
[00:50:02] <Valen> from their manual for the 7i40 "This page intentionally almost blank"
[00:57:39] <SWPadnos> most of their manuals have that
[00:57:46] <SWPadnos> I like it too :)
[02:14:36] <Jymmm> SWPadnos: how goes it?
[02:15:00] <SWPadnos> so-so
[02:15:12] <Jymmm> pregnant with tripplets?
[02:15:22] <SWPadnos> not that I know of
[02:15:34] <Jymmm> lol
[02:15:41] <Jymmm> why soso?
[02:16:05] <SWPadnos> several reasons
[02:16:18] <Jymmm> pregnancy isn't one of them
[02:16:26] <SWPadnos> 1) the washing machine died this weekend (with a load in it, of course)
[02:16:34] <Jymmm> CL
[02:17:03] <Jymmm> CL alwasy has W&D, many free even
[02:17:18] <SWPadnos> 2) I needed some parts from DigiKey today, but missed the ordering cutoff on Friday. Then their credit card processing system was down this evening, so I couldn't order today either
[02:17:28] <Jymmm> yuck
[02:17:35] <SWPadnos> (so now I'm 2 days late getting this stuff, which will hold up other things)
[02:17:52] <SWPadnos> and 3) I'm so far behind on another project that I can't even estimate how much extra time I need
[02:17:57] <Jymmm> overnight delivery?
[02:18:00] <SWPadnos> said estimate being due tomorrow morning
[02:18:03] <SWPadnos> yes
[02:18:22] <SWPadnos> so as I say, so-so
[02:18:38] <SWPadnos> oh, and my wife is planning a nice trip, which she has to take without me because I have so much work to do
[02:18:46] <Jymmm> Hmmm, go hug your SS enclosure, it'll make yu feel better.
[02:18:59] <SWPadnos> yes. it's probably cooler in the garage
[02:19:14] <Jymmm> SWPadnos: Oh did you see the fan I posted?
[02:19:22] <SWPadnos> a non-Lasko?
[02:19:27] <Jymmm> http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100662921#reviews
[02:19:43] <Jymmm> $40 of awesomeness, and much quieter than the old pattons
[02:19:58] <Jymmm> Even on LOW it moves some ar
[02:20:00] <SWPadnos> cool
[02:20:24] <Jymmm> On HIGH, just attach wings and a couple RC servos
[02:20:36] <Jymmm> and a REALLLLLLLLLLLLLLLLLLLLLLLY long ext cord
[02:21:03] <Jymmm> I went back and bught another one actually.
[02:21:14] <SWPadnos> great
[02:22:15] <Jymmm> SWPadnos: you could care less right abut now, huh?
[02:22:21] <SWPadnos> more or less ;)
[02:22:55] <Jymmm> SWPadnos: Hey it's all good... you just mentioned "cooler in the garage" which implied hot in the house, so I thought that might help out in that dept.
[02:23:16] <SWPadnos> it's not hot, about 76 in my office
[02:23:24] <Jymmm> and humid
[02:23:26] <Jymmm> ?
[02:23:35] <SWPadnos> not especially
[02:23:39] <Jymmm> it's just balmy here
[02:23:41] <SWPadnos> I think it didn't rain today
[02:24:02] <SWPadnos> or yesterday (much), come to think of it
[02:24:29] <Jymmm> Didn't rain here either, just balmy thae last two das
[02:25:26] <Jymmm> SWPadnos: well, I know it's almost your bedtime, so hasta!
[02:25:34] <SWPadnos> see you
[02:25:53] <Jymmm> SWPadnos: Go kick a (ceramic) cat or soemthing
[02:25:56] <Jymmm> ;)
[02:26:07] <SWPadnos> no time for that
[02:45:44] <Valen> 's a fairly cool looking fan
[02:50:02] <mozmck> any idea why axis would show up with a blank window and hang the machine?
[02:50:38] <cradek> non-working opengl?
[02:50:43] <mozmck> a guy on the forum is having that happen
[02:51:06] <mozmck> hmm, how would I have him check for that?
[02:51:15] <cradek> run another opengl program like glxgears
[02:52:00] <mozmck> Ok. I told him to make sure visual effects were turned off. I had the backplot do funny stuff on one machine when they were on
[02:52:08] <cradek> yep
[02:52:13] <cradek> also good advice
[02:52:28] <jepler> ubuntu turns on "desktop effects" for certain Intel video chipsets even though it is broken in the way you described
[02:52:46] <jepler> .. for nearly two years, and by default, despite a huge number of duplicate bugs filed about it
[02:52:52] <cradek> not if you install with the linuxcnc cd
[02:52:54] <mozmck> I would presume opengl is there because if it is not axis gives an error and exits.
[02:52:56] <jepler> their answer is "nobody uses opengl and doesn't run fullscreen, since it's for games"
[02:53:07] <mozmck> heh.
[02:53:19] <cradek> there is a lot of advice recently to avoid our cd - I'm not sure why.
[02:53:43] <mozmck> I don't know how he installed. I just used a standard ubuntu cd on the computer aforementioned.
[02:54:00] <cradek> yeah, that would do it, depending on your video card
[02:54:01] <mozmck> don't know. I haven't tried it yet myself.
[02:54:05] <Valen> who is giving said advice?
[02:54:19] <cradek> Valen: I've seen it several times on the emc-users list
[02:54:52] <Valen> I think it might be because you can get the 8.04.1 CD which has better hardware support
[02:54:58] <Valen> IE atom stuff and other such
[02:55:09] <cradek> if you then replace the kernel with ours, I bet those benefits go away
[02:55:25] <mozmck> I think so.
[02:55:28] <Valen> 's entirley possible
[02:55:47] <mozmck> one guy on the forum had some problem like that and had to change some hardware.
[02:56:05] <Valen> but you do at least have the option then of compiling your own kernel for it, if you only have the emc disk you cant actually install
[02:56:24] <cradek> I see
[02:56:46] <mozmck> how hard would it be to put the development packages on the CD?
[02:56:55] <Valen> I only know that for certain on atom though
[02:57:19] <cradek> mozmck: I think the cd runs pretty full, alex would know for sure
[02:58:07] <mozmck> how is the cd made? can stuff like openoffice be stripped out - or is it already?
[02:58:45] <cradek> it could be
[02:58:54] <cradek> but this way lies madness IMO
[02:59:03] <cradek> the less we modify ubuntu the better
[02:59:40] <Valen> Might be an idea to have a super small livecd so people can test their hardware
[02:59:48] <mozmck> probably so.
[02:59:59] <Valen> then just use the packages ontop of a standard install
[03:00:00] <cradek> the best test is the full cd
[03:00:19] <cradek> heh, that's where we started some time ago
[03:00:29] <cradek> people really really wanted a full OS cd
[03:00:36] <cradek> all this talk about no internet access at the machine
[03:01:57] <mozmck> that's why I wondered about the dev packages, because I've seen several people asking how to upgrade without a net connection.
[03:02:22] <cradek> you don't need dev packages to upgrade - so maybe I don't understand what you're asking
[03:02:41] <mozmck> If they need to install components they will need dev
[03:02:48] <cradek> yes
[03:02:59] <cradek> but not to upgrade to newer packaged versions
[03:03:27] <mozmck> no, but if the dev is not there and they want to add it...
[03:03:38] <mozmck> it requires a lot of extra packages
[03:03:58] <cradek> yeah getting the full compiler etc is a pain without a net connection
[03:04:08] <cradek> also that's a sign that it wouldn't all fit on the cd :-/
[03:04:16] <mozmck> maybe we could put a list of required packages or something that would make it easier
[03:05:00] <cradek> mozmck: http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?UpdatingTo2.3
[03:06:07] <cradek> also apt already supports something like what you want with --print-uris (you can get a list of things to go elsewhere and download)
[03:06:36] <mozmck> ah, I need to read more... lots of stuff out there!
[03:07:12] <mozmck> for someone new to linux it's not easy to figure it all out
[03:07:32] <cradek> yep
[03:07:42] <cradek> easier to run some cat5 than figure out apt
[03:08:34] <Valen> much ;->
[03:11:54] <Jymmm> also, the updates
[03:12:04] <sed_> we are tuning an axis, in manual mode it moves perfectly, in MDI or audo its all over the place..
[03:12:29] <cradek> define all over the place
[03:13:16] <Valen> I think i rember vuagley an ubuntu project to do that whole offline online thing
[03:14:23] <SWPadnos> there was a project that would let you configure a system as you liked, and then would create either a CD or a list of installed packages, which could then be installed elsewhere easily
[03:14:42] <sed_> on the down side of the scope pattern it slows down and its as if it doesent have enough power to make it to position, and falls short
[03:15:49] <sed_> It acts like it runs from another set of PID settings when using MDI or Auto verses manual 1" steps
[03:16:08] <sed_> The acceleration and velocity are different
[03:16:39] <mozmck> SWPadnos: that sounds interesting. any idea what it was called?
[03:16:41] <Valen1> whats the consensus on this http://cgi.ebay.com.au/1000W-48V-20A-Switching-Power-Supply-Radio_W0QQitemZ190318518154QQcmdZViewItemQQptZAU_Security_Equipment?hash=item2c4fde1f8a&_trksid=p3286.m20.l1116 as a PSU for some CNC type lovin
[03:16:44] <Valen1> 4x 500W motors
[03:16:46] <SWPadnos> nope
[03:17:31] <cradek> sed_: running gcode in g64 (blending) mode will give you half the acceleration on some (many) moves
[03:17:49] <cradek> do you mean 1" incremental jogs?
[03:18:11] <cradek> is that long enough to make it up to cruise velocity? have you tried longer and shorter jogs?
[03:18:50] <sed_> I am not running G64. and yes incremental jogs. The deceleration is faster than accceleration in G0Y1 move
[03:19:06] <cradek> have a plot?
[03:19:16] <cradek> commanded accel and decel are the same
[03:20:05] <sed_> Longer distance MDI commands end up with a following error even though I have FERROR set to 1.000".
[03:20:13] <sed_> Not according to the scope
[03:20:28] <cradek> show me
[03:20:48] <cradek> if you get ferror trips, the position has become that far behind
[03:20:49] <Jymmm> * Jymmm streaks across the channel
[03:21:31] <Jymmm> cradek: Seen enough yet?
[03:21:35] <sed_> I have also set the ferror to 2" and still have the problem only when moving less than 1/2"
[03:23:50] <Jymmm> ValenThis is what you NEED... http://cgi.ebay.com/ELECTRICAL-TRANSFORMERS-1000-KVA-13800-277-480Y-VOLT_W0QQitemZ130291505582QQcmdZViewItemQQptZBI_Circuit_Breakers_Transformers?hash=item1e55fa99ae&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A2149%7C293%3A1%7C294%3A50
[03:27:04] <Valen1> yaknow mu mill isnt actually that big
[03:27:30] <Jymmm> just use it as the BASE =)
[03:28:03] <Valen1> There should be some "its Australian for plugpack" line in there somewhere
[03:28:03] <Valen1> geez at $10k it'd be almost worth it for scrap
[03:28:48] <Jymmm> http://cgi.ebay.com/35-35V-600VA-Toroid-Transformer-CNC-Controller-HiFi_W0QQitemZ370192780213QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item5631358bb5&_trksid=p3286.m20.l1116
[03:29:11] <Jymmm> Isn't it 35VAC * 1.414 = 49.49 VDC ?
[03:42:24] <Valen1> Jymmm prolly the psu i found is dc out?
[03:42:57] <Valen1> thing is theoretically I can only wind it down to 42 volts
[03:43:12] <Valen1> think that would be too high for the 40v version of the 7i40?
[04:18:08] <Valen1> Can i get EMC to limit rates based on total acceleration of 3 axies?
[04:18:23] <Valen1> IE if my power supply isn't beefy enough to drive all motors at full power?
[04:18:40] <Valen1> but it can run 2 out of 3 at full power
[04:18:55] <Valen1> Or do I have to limit all the motors to 1/3rd of the available power all the time
[04:18:55] <cradek> no
[04:19:12] <cradek> all three x,y,z accel at the same time is a rare move
[04:19:17] <cradek> like 0,0,0 to 1,1,1
[04:19:25] <cradek> if you do 2.5d style milling you'll never have that
[04:19:30] <Valen1> rare but i still don't want to smoke the power supply
[04:19:38] <Valen1> We are hoping to wind up at 5 axis
[04:19:46] <cradek> sounds like the place to fix that is the power supply
[04:20:00] <Valen1> that costs money though ;->
[04:20:03] <Valen1> software is cheap
[04:20:07] <cradek> are you talking about steppers?
[04:20:12] <Valen1> servo
[04:20:34] <cradek> ok
[04:20:40] <Valen1> I'm mainly looking to ensure that a "worst case event" doesn't smoke the PSU
[04:21:05] <Jymmm> fuse it
[04:21:07] <Valen1> hmm I spose that can also be known as a fuse
[04:21:08] <cradek> what kind of power supply?
[04:21:59] <Valen1> http://cgi.ebay.com.au/1000W-48V-20A-Switching-Power-Supply-Radio_W0QQitemZ190318518154QQcmdZViewItemQQptZAU_Security_Equipment?hash=item2c4fde1f8a&_trksid=p3286.m20.l1116
[04:21:59] <Valen1> switchmode
[04:21:59] <Valen1> cheap chinese style
[04:22:08] <Valen1> We have some of their 12V supplies, they seem pretty good
[04:22:31] <Valen1> hmm it says it has overload protection I spose
[04:22:33] <cradek> generally you can short a switcher without damaging it - it just shuts off
[04:22:53] <Valen1> yeah, it is chinese though
[04:23:12] <Valen1> Ah well Get one i spose and if its an issue get another
[04:23:57] <geo01005_home> just don't put them in parallel.
[04:24:18] <geo01005_home> it doesn't look like they are designed to do load sharing.
[04:47:00] <Valen1> nah I'll put one to each controller
[09:27:14] <piasdom> g'mornin all
[11:35:37] <Xteven> hi
[11:37:23] <micges> hello
[11:43:14] <Xteven> EMC looks interesting
[11:44:28] <Xteven> I was on my way to build a cnc machine from scratch with a couple stepper motors, but didn't know how to translate a drawing into commands that my cnc machine would understandn
[11:45:29] <Xteven> does EMC assume a certain setup (like commercial steppermotor controllers or using a parallel port or USB or so) or is it flexible enough ?
[11:45:39] <pjm__> Xteven yes EMC is truely excellent, I started in much the same way with some steppers and driver boards then built a milling m/c
[11:45:39] <archivist> here are some ideas http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Cam
[11:45:57] <pjm__> pjm__ is now known as pjm
[11:46:11] <Xteven> wow nice
[11:46:17] <archivist> Xteven, I also did a from scratch cnc
[11:46:19] <pjm> pjm is now known as pjm1
[11:47:26] <pjm> bah wrong button!
[11:47:31] <Xteven> cool :)
[11:48:55] <Xteven> I suppose I should learn more about gcode
[11:50:06] <archivist> some of us hand code
[11:50:30] <archivist> I do because Im making gears
[11:51:43] <Xteven> what I'm most scared of is having to implement some arc-drawing code
[11:52:11] <archivist> I cheat... rotate the A axis
[11:53:00] <archivist> there are some wizards to help with arcs
[12:01:29] <Xteven> is there a list of the things a CNC machine should be able to do if I want to use it with EMC2 ?
[12:03:43] <archivist> I dont think so, its up to your imagination
[12:04:33] <archivist> often a machines construction and shape places limits not the cnc software
[12:05:17] <BigJohnT> unless you mean the drivers for the steppers or servos
[12:05:28] <Xteven> I should be more clear ;)
[12:05:55] <Xteven> my cnc machine would move in X and Y direction
[12:06:09] <Xteven> drawing lines is not a problem, but drawing an arc would be
[12:06:14] <archivist> and Z we hope if a mill
[12:06:22] <Xteven> does EMC translate the arc in a sequence of straight lines ?
[12:06:29] <BigJohnT> why is that
[12:06:29] <Xteven> well yes, that too :)
[12:07:17] <archivist> yes gcode has arcs
[12:08:59] <Xteven> does the hardware need to know how to draw an arc ?
[12:09:12] <archivist> no
[12:10:04] <Xteven> ah ok :)
[12:10:29] <archivist> EMC knows
[12:10:40] <archivist> or your cam software
[12:11:17] <archivist> or cheat and have rotary axes
[12:14:42] <Xteven> I'll give this a go
[12:14:49] <Xteven> and hopefully start building soon
[12:15:23] <Xteven> thx for the info
[12:15:29] <archivist> what do you intend making
[12:18:13] <Xteven> I'm already in love with emc
[12:18:14] <Xteven> ;)
[12:18:16] <Xteven> well
[12:18:23] <Xteven> I just want to make a simple cnc machine
[12:18:35] <Xteven> mainly to drill holes on PCB's I guess
[12:18:46] <Xteven> but probably also for all kinds of other interesting projects
[12:19:23] <archivist> some are milling the tracks as well
[12:19:48] <Xteven> yeah I saw that :)
[12:51:05] <Xteven> archivist: how many axis does your machine have ?
[12:51:23] <archivist> 5
[12:52:06] <archivist> built up from scrap and a couple of new rotaries
[12:52:36] <Xteven> wow
[12:53:00] <Xteven> emc must be made up of magic
[12:54:17] <archivist> EMC can handle 9 axis
[12:54:34] <Xteven> this has a lot of potential :)
[12:54:47] <Xteven> I was imagining I had to write all the controller software myself
[12:54:55] <Xteven> luckily, I'm wronng
[12:55:06] <Xteven> now I can focus on building hardware
[12:55:11] <Xteven> which is my favorite part
[13:00:09] <Xteven> there's a bunch of videos on youtube of CNC machines controlled by EMC2
[13:03:44] <pjm> one of them vids should be my machine!
[13:04:09] <pjm> a few picture of my mill at http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Pjm
[13:04:17] <archivist> I may admit to some
[13:16:24] <Xteven> oh btw
[13:16:38] <Xteven> I was looking for cad software for linux earlier
[13:16:52] <Xteven> do you use any ? if so, which ?
[13:17:07] <archivist> thats why I pointed you at the cam page
[13:17:18] <Xteven> ah :)
[13:17:40] <archivist> Im part of the group building HeeksCAD
[13:17:52] <archivist> Im testing mainly
[13:18:28] <Xteven> cool
[13:18:50] <Xteven> I've tried a couple CAD programs, but a lot of them seem unfinished and missing basic functionality
[13:18:58] <Xteven> I'll look at heekscad
[13:19:18] <archivist> most are unfinished
[13:19:38] <archivist> define "basic functionality"
[13:20:08] <pjm> Xteven not *nix but windows, cambam is simple and pretty good
[13:20:13] <Xteven> well, not crashing for example
[13:20:51] <Xteven> hmm
[13:21:20] <Xteven> looks nice
[13:21:31] <Xteven> I've played with qcad before, its very good
[13:21:34] <Xteven> but only 2D
[13:23:35] <pjm> yes the current cambam is pretty nice, it supports proper 3d profiling too
[13:23:42] <pjm> not had cause to use that as yet
[13:56:28] <A4NDY> what do you think about using "voice" to control movement, motor ...just like HDD voice-coil to control its head
[13:56:32] <A4NDY> ?
[13:57:36] <archivist> as long as servo controlled and has enough force and damping for the job
[13:58:01] <A4NDY> :)
[13:59:13] <A4NDY> enough force, thats a good thing to consider...
[13:59:53] <archivist> what application do you have in mind
[14:00:18] <A4NDY> maybe mini-CNC for building mini robotic parts
[14:00:34] <A4NDY> its a medical stuff
[14:01:16] <A4NDY> no one on earth go healty for forever
[14:01:53] <A4NDY> so, cheap tools must be easy to build and exist anywhere
[14:02:57] <archivist> voice coil has a limit to the force it can resist from the machine
[14:04:06] <A4NDY> ... and other problem is the drill stuff
[14:04:11] <A4NDY> mini one
[14:05:50] <A4NDY> handphone vibrate motor?
[14:06:09] <A4NDY> how about home made voice coil?
[14:06:51] <archivist> magnetics are not easy
[14:06:53] <A4NDY> its a 1 magnet + 1 coil winding(like tesla)
[14:07:44] <A4NDY> no magnet, we can create it/ repalce it with other 1 coil winding
[14:08:11] <A4NDY> + iron core
[14:08:33] <A4NDY> like speakers
[14:08:44] <A4NDY> "Speaker"
[14:09:12] <archivist> a speaker has exceedingly small gaps and very high magnetism
[14:09:43] <A4NDY> since human can hear ?hz - 22khz
[14:09:59] <A4NDY> so speed is 22khz
[14:10:23] <jepler> but what's the torque of a speaker? what is the positioning accuracy? what is the positioning range?
[14:10:24] <archivist> nothing to do with hearing its to do with the mechanical efficiency of movement
[14:10:34] <A4NDY> ...small gaps, good to consider...
[14:11:39] <toastatwork> the gaps on my woofers are less than .5 mm
[14:11:44] <A4NDY> jepler, go made a experiment on broken HDD, to see its stability on a STATE, and the precise on POSITION
[14:11:49] <archivist> and 22khz is getting beyound EMC's cycle time, it cannot be controlled
[14:11:58] <A4NDY> ... but force.. we need to build bigger one
[14:12:03] <jepler> even for a small CNC torque is in the range of .1 newton-meter. positioning accuracy is in the range of .01mm. range is 200mm
[14:12:08] <A4NDY> ;)
[14:12:29] <jepler> A4NDY: and when you put +-.1Nm force on the hard drive actuator, does it stay in position?
[14:12:48] <A4NDY> gaps on motor also abit the same
[14:13:07] <A4NDY> SOUNDCARD is the best choice
[14:13:11] <archivist> I have seen large voice coil mechs from IBM disks circa 1970
[14:13:37] <archivist> sound cards do not make servos
[14:13:48] <toastatwork> competition subwoofer voice coils are 4"+ in diameter
[14:13:52] <toastatwork> if you're looking for force.
[14:14:59] <A4NDY> how about big amplifier + big 'voice coil, home made'
[14:15:15] <Valen> your best bet would be a solinoid
[14:15:18] <A4NDY> ...yes it is alot to consider
[14:15:22] <toastatwork> * toastatwork shrug
[14:15:25] <Valen> I was looking at it for a full sized mill
[14:15:27] <toastatwork> it's about the same thing
[14:15:36] <Valen> it was close to working in terms of numbers
[14:15:46] <toastatwork> the only difference is the gap and motor hang are pretty rigidly controlled in a competition coil
[14:15:49] <Valen> needed a neodinium magnet about the size of a football though
[14:16:19] <Valen> and I didn't want to stand next to it when it was in operation
[14:16:26] <toastatwork> i'm sure if you were careful you'd not have a problem winding your own.
[14:16:31] <Valen> The biggest issue was damping vibration and the like
[14:16:42] <A4NDY> JUST replace the PERMANENT MAGNET, with electric-COIL-MAGNET.... ;)
[14:18:11] <A4NDY> yes, some ripple on pre-amp would jold it
[14:18:36] <Valen> We were also thinking we would need to water cool the coil
[14:18:56] <jepler> Valen: in your design did you have a linear scale or something? I don't see how this works without position feedback..
[14:19:07] <A4NDY> might be
[14:19:17] <Valen> yeah you know how I love the linear scales ;->
[14:20:16] <A4NDY> btw. is there any HOME-MADE linear scale ?
[14:20:35] <Valen> a ruler and a camera ?
[14:20:54] <A4NDY> (i really need it beside 'my common' encoder)
[14:21:05] <Valen> accuracy is hard to invent from first principles
[14:21:24] <Valen> The only way your going to even be able to mark it accuratly is with an interferomiter and a kickass laser
[14:22:20] <jepler> yes, the precision of position feedback should be several times higher than the actual positioning accuracy
[14:22:36] <archivist> factor of 10
[14:22:55] <archivist> and sound card dont cut it
[14:23:04] <A4NDY> i wonder to "print" linear scale like we use to SEE on our DESKJET PRINTER (canon,hp,epson,etc)
[14:23:12] <Valen> yay our mill should hit .01 mm accuracy ;->
[14:23:35] <archivist> printers are crapish
[14:25:00] <A4NDY> a TAPE from our oldy TAPEDECK or VIDEOTAPE would do !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
[14:25:10] <A4NDY> haha
[14:25:33] <A4NDY> its a magnetic tape
[14:26:05] <A4NDY> u can read/write it using your oldy head-tape
[14:26:46] <toastatwork> not many positioning devices, especially not interferometers, have a 22 khz read speed
[14:27:09] <A4NDY> u still remember floppy disk right
[14:27:31] <A4NDY> how hast is it..
[14:28:04] <A4NDY> fast... is not too important for the buldozer cnc
[14:31:09] <A4NDY> the speed of floppy-head is still faster for our need
[14:31:52] <A4NDY> tape is easy to replace also
[14:32:57] <A4NDY> problem is how to GLUE it to its rail, and consider the space-gap if ure using floppy head
[14:33:57] <jepler> the idea of using unrolled cassette tape media for a homemade linear scale is interesting. The play rate is 4.76cm/s and the better media could store a 20kHz signal (according to wikipedia). That gives one cycle per 2.38um; in quadrature that gets you about .6um per edge. but how can you be sure you accurately recorded your 20kHz quadrature signal?
[14:34:01] <A4NDY> go see magnetic strip card for refference
[14:34:31] <toastatwork> jepler that's pretty much the main problem nowdays
[14:35:05] <toastatwork> getting nanometer resolution isn't particularly spectacular considering what's available, but getting it to resemble a meter is difficult
[14:35:27] <A4NDY> the STUFF u need is a FREQUENCY-GENERATOR, using a X-TALL
[14:35:37] <jepler> you mean "stuff", "frequency generator" and "crystal"
[14:35:41] <A4NDY> ALL RADIO HAVE IT... ;)
[14:35:44] <jepler> oh, and "you"
[14:36:01] <A4NDY> device to record the polse
[14:36:08] <A4NDY> to the tape
[14:36:16] <toastatwork> uh, where are you going to get a copy of a meter to calibrate your whole shenanigan
[14:36:37] <toastatwork> or even a reasonable facimile at much lower tolerances (i'm assuming)
[14:37:03] <jepler> generating an accurate 20kHz signal is not difficult, but how do you make sure that the rate the tape is passing under the recording head is 4.76cm/s +- .6ppm?
[14:37:32] <A4NDY> :)
[14:37:35] <A4NDY> :)
[14:37:39] <A4NDY> SIMPLE
[14:37:42] <jepler> (that's .6um/1m or an error of one edge per meter of scale))
[14:39:19] <A4NDY> USE your already have encoder to role the tape using gearbox to gain more accuracy, BETTER than your original encoder
[14:39:31] <cradek> stretch would be a problem I'm sure
[14:39:49] <cradek> if you have any repeatable positioning, it's an easy matter to calibrate it (like screw compensation)
[14:40:12] <A4NDY> NOT REALLY
[14:40:19] <jepler> please do not shout
[14:40:19] <cradek> stop yelling
[14:40:46] <A4NDY> hahha, ill explain u how
[14:41:22] <A4NDY> (im so excite/happy... thats why im using big char)
[14:41:45] <toastatwork> you guys have pretty accurate rotary encoders, right? lap a wheel to a known diameter with a gage block and indicator, and use the wheel to drive the tape past the read head.
[14:42:17] <A4NDY> common this is a invention, small excite invention, so please is its useable, go build one and publise it on yourhomepage
[14:42:30] <A4NDY> here, how to
[14:42:39] <A4NDY> the streech problem
[14:42:47] <archivist> A4NDY, you build
[14:42:48] <cradek> all I'm saying is you can't trust magnetic tape to ever be the same length twice
[14:43:10] <A4NDY> yes me too, its just came to mind
[14:43:28] <jepler> cradek: yeah, I agree -- if you do anything but record it in place
[14:43:45] <archivist> cradek, UK company makes glue on strip encoders
[14:43:52] <Valen> The big problem with using a tape is you can only read it while its moving
[14:43:55] <A4NDY> cradek hahahahaha.... here we go my solve:
[14:44:28] <toastatwork> valen the same is true of other encoders
[14:44:35] <toastatwork> they're just pulses
[14:44:45] <toastatwork> if it isn't pulsing, you're not moving, so it's okay to assume you're in the same spot
[14:45:03] <Valen> yeah but if you are moving "really slowly" you will be getting ~0 volts out of your read head
[14:45:13] <Valen> at high speed you will be getting say a volt
[14:45:25] <toastatwork> so the size of the pulse is velocity dependent?
[14:45:33] <jepler> yeah -- a similar problem exists trying to use a stepper as an mpg
[14:45:34] <pcw_home> GMR read head = dc coupled
[14:45:35] <toastatwork> (i don't know jack about magnetic read heads, just curious)
[14:45:36] <Valen> the voltage yeah
[14:45:38] <A4NDY> just place the blank tape on your rail first, assemble your cnc, THEN the head that moving using old encoder move 1 way and write it pulsw
[14:45:51] <Valen> time measurement is fairly easy to do, so getting a drum to rotate at a set speed shouldn't be that hard with a gps synchronised clock signal
[14:45:57] <A4NDY> haha
[14:46:33] <Valen> I can see that netting you .001mm markings without too much of a problem
[14:46:40] <A4NDY> thats way, we could ignore stech problem
[14:47:03] <Valen> Personally I think the old "ball bearings in a tube" trick is probably a better way of "inventing" accuracy
[14:47:10] <Valen> well good enough anyway
[14:47:20] <A4NDY> strech on placing the ape on
[14:47:26] <A4NDY> strech on placing the tape on
[14:47:39] <jepler> when you go into production you'd probably want to just apply the magnetic coating directly to a narrow plate, rather than start with a tape
[14:48:39] <Valen> hmm theres a question, whats the "width" of the track on a CD?
[14:49:09] <cradek> seems like there are lots of existing (working) linear scale technologies to choose from
[14:49:42] <toastatwork> heathen, other people invented those technologies
[14:49:47] <toastatwork> ours will be better because we did it
[14:49:48] <Valen> I'm thinking if you rip apart a CD mechanism and drive it just to the side of the hole (so its always over a data section) you could read the servo tracking bumps different from the data section
[14:49:49] <jepler> Valen: first figure I found on wikipedia says 500rpm 150KB/s
[14:50:07] <Valen> thats the linear size though
[14:50:11] <A4NDY> i answer the question for mr.cradek ...haha ...i do this cos other share their though, now its my turn
[14:50:13] <Valen> I'm talking about running radially across the surface
[14:51:27] <A4NDY> ... ure talking about using CDROM as encoder
[14:51:28] <A4NDY> ?
[14:51:33] <jepler> Valen: well, that gives 144kB/revolution, or ~4600 revolutions/640MB
[14:52:20] <Valen> yeah that sounds somewhere in the ballpark
[14:52:35] <jepler> it can't be as simple as that, though, because isn't CDROM CLV?
[14:52:49] <Valen> assuming one peak and land for servo groove and data your looking at .007mm per track
[14:53:34] <archivist> and on crappy plastic that expands with temperature
[14:53:35] <jepler> but aren't you limited to travel of under 1 CD radius?
[14:53:43] <pcw_home> The mylar strips in inkjet printers and their read heads
[14:53:45] <pcw_home> are probably a good place to start playing with linear encoders
[14:53:50] <A4NDY> JUST jumper the write laser if u wanna to do so
[14:54:02] <Valen> yeah under one cd width
[14:54:02] <A4NDY> as simple as that
[14:54:07] <Valen> was just a thought
[14:55:16] <jepler> cdrom as rotary encoder sounds more interesting to me
[14:55:25] <A4NDY> speed of WRITE is not important !!!!!
[14:55:47] <jepler> if only you had a cdrom that could track no matter which direction the head is moving
[14:55:55] <A4NDY> then the rest is ... u know the cd/dvd speed
[14:55:59] <A4NDY> of read
[14:56:07] <A4NDY> ;)
[14:56:41] <jepler> now you've got a 4kturn absolute rotary encoder with a precision of 5e-6 radians
[14:57:07] <jepler> .. except for all the little problems that crop up when you try to actually do it
[14:58:06] <Valen> jepler put multiple readers one one cdrom
[14:58:50] <Valen> offset them just a little and you get direction
[14:59:39] <jepler> aren't there bit patterns related to LFSRs that allow you to determine both absolute position and direction? I have a vague memory of this..
[14:59:41] <Valen> Only issue your going to have as well is the data on a CD is encoded so you cant just write a string of zeros to it, and you might wind up with DC offset problems when you try to go slowly again
[15:00:01] <Valen> i'd imagine you could do something along those lines
[15:00:43] <Valen> a grey code of some description unless you were able to let it rotate some before getting an absolute position lock
[15:01:20] <Valen> Personally I'd rather make a mill (with magic) that runs the whole time from "first principles"
[15:01:29] <Valen> IE everything is based on light
[15:01:55] <A4NDY> nice
[15:01:59] <Valen> interferomiter for length measurements, and beam following for straightness
[15:02:01] <jepler> yeah, the kind of scheme I'm talking about assumes you can move just a bit
[15:02:17] <jepler> you need to see a bunch of adjacent states to reconstruct the bit generator's internal state
[15:02:34] <Valen> yeah if you can do that you could encode absolute position along the rotation
[15:04:32] <Valen> whats a "first principles" way of measuring angle for a full rotation?
[15:07:57] <pcw_home> Just us FM or MFM encoding, clock bits are relative position between absolute codes
[15:08:17] <archivist> I think the best circles were made with worms and wheels, but via a few generations to average out the errors and the wheel gets sliced to distribute the error
[15:09:11] <A4NDY> thats a good one to conseder, IF we made encoder using a CD
[15:09:44] <A4NDY> '/DVD ... pulse of 1 cycle
[15:09:57] <A4NDY> of DVD/CD
[15:10:48] <Valen> I'm wondering if you set up a standing wave in an optical fiber around a "round" you could read that by looking at the leakage out the side of the fiber
[15:10:52] <A4NDY> last pulse and first pulse... would have a gap
[15:11:20] <Valen> measuring how out of round the round is would compensate that and is doable with an interferomiter
[15:11:43] <A4NDY> so buy a encoder rotary is cheap .... (linear encoder is expensive)
[15:13:04] <A4NDY> my solve of linear encoder (write on first cnc start) would not generate this such a problem
[15:13:29] <A4NDY> ;)
[15:14:25] <A4NDY> cos its a single line.... but we have problem on how to glue it on the rail
[15:14:47] <A4NDY> tape strip is plastic, rail is iron/metal
[15:15:12] <A4NDY> any suggestion
[15:16:14] <A4NDY> ?
[15:17:17] <pcw_home> Yah, use the mylar strip encoder from a defunct printer
[15:21:27] <A4NDY> <archivist> printers are crapish
[15:21:59] <pcw_home> contact readers are crapish
[15:24:25] <A4NDY> floppy-head on tape strip
[15:25:18] <A4NDY> contact readers slow yes
[15:25:52] <pcw_home> AC coupled = wont work
[15:26:37] <pcw_home> counts lost below some speed threshold
[15:27:08] <archivist> floppy head will not read statically== useless for low speed
[15:28:24] <archivist> A4NDY, stop dreaming and spend some time seeing how real systems work
[15:28:42] <A4NDY> (archivist, i just know it from u) so we only have tape-head, contact readers
[15:30:04] <A4NDY> just a thought, im using ordinary encoder in today works
[15:31:12] <A4NDY> do u have any refference on 'low-cost' linear encoder...
[15:31:28] <archivist> define low cost
[15:31:36] <A4NDY> cheapest
[15:31:46] <A4NDY> just cheapest
[15:32:20] <A4NDY> i have dificulty time on its demand
[15:34:23] <A4NDY> accurate and robust is common
[15:35:00] <A4NDY> 6meter long
[15:39:18] <alex_joni> A4NDY: what resolution?
[15:39:36] <alex_joni> there are some wire+spools for measuring
[15:39:55] <alex_joni> you strap it to one end of the axis, the end of the spool to the moving part, and it outputs position
[15:40:04] <alex_joni> it's accurate to some .1mm or so
[15:40:15] <A4NDY> 0,1mm or 1mm
[15:40:25] <A4NDY> 0,01mm?
[15:41:04] <A4NDY> thats would do. :)
[15:42:25] <A4NDY> the length of linearscale 6-12meter is a problem on shipment...
[15:47:01] <A4NDY> (please i need suggestion, ill go check the answer on log tomorrow) :) ....thanks guys
[15:52:04] <archivist> heh voice coil and 12 meters in the same session....
[15:52:54] <pjm> OT: archivist btw dunno if u know but NASA are re-running the apollo 11 comm as it happened + 40 years at http://www.nasa.gov/externalflash/apollo11_radio/
[15:53:58] <archivist> pjm also off topic ish Sandown ME show december
[15:54:37] <pjm> ahh as in IOW sandown?
[15:55:56] <archivist> Sandown Park Racecourse, Esher
[15:56:37] <archivist> 11-13
[15:56:59] <pjm> ahh that one, yeah thats not too far up the road
[15:57:10] <pjm> didnt they have a vhf conference there once, cant remember
[15:57:17] <archivist> a way down the road for me
[15:58:14] <archivist> I have been to a few things there
[16:00:43] <archivist> dunno what finances will be like then, job should be dead then
[17:40:12] <Xteven> I'm impressed with EMC2's documentation
[17:40:26] <Xteven> actually, with pretty much everything in it
[17:40:28] <BJT-Work> :)
[17:40:38] <Xteven> how come something this great exists and I don't know about it ?
[17:40:56] <Xteven> must be because of my tendency to reinvent the wheel with microprocessors
[17:41:51] <Xteven> I've reclaimed a P4 desktop machine I have running around
[17:41:54] <Xteven> it has a parallel port
[17:43:34] <Jymmm> Xteven: Download the LiveCD, MD5 the ISO, burn at4x speed, boot off of the CD and run the latency test for 24 hours to see if your system will work well with emc.
[17:49:01] <Xteven> 24 hours ?
[17:49:02] <Xteven> hmm
[17:49:09] <Xteven> I will do that in the next couple of days
[17:50:04] <Jymmm> Xteven: You can use the system while it's running the latency test, actually better if you load it up use and abuse it as much as possible.
[17:50:16] <Xteven> ah
[17:50:24] <Xteven> I plan to use it for EMC2 exclusively
[17:50:32] <frallzor> is there come compensation for play in emc?
[17:50:35] <frallzor> *some
[17:50:38] <Jymmm> It's still ubuntu
[17:50:47] <Xteven> well, maybe I can use it as a radio in the basement too
[17:50:48] <Xteven> :)
[17:51:03] <Jymmm> radio, surfing, email, video,etc
[17:51:12] <Xteven> I'll do it all
[17:55:36] <frallzor> ah backlash was the word, is there compensation for that in emc?
[17:56:01] <archivist> yes but dont have any to compensate
[17:56:17] <Jymmm> Yes, but mechancial correction is FAR better
[17:57:08] <Jymmm> archivist: smartass
[17:58:03] <roh> .oO(is that what you get for not using cnc parts?) *ducks*
[17:58:16] <Jymmm> archivist: Oh, I thought you were saying YOU dont have any backlash.
[17:58:29] <archivist> I do and its a pain
[17:58:45] <Xteven> backlash sucks
[17:58:59] <archivist> it breaks tools
[17:59:03] <Jymmm> archivist: Well, in the words of LArry the cable guy.... GIT ER DONE
[17:59:21] <archivist> gimme money to git done
[17:59:44] <roh> are ballscrews so expensive?
[17:59:51] <Xteven> but you could counter it by having 2 thingies on the threaded rod that are forced outwards
[17:59:52] <Jymmm> * Jymmm hands archivist a pair of fishnet stocks and a tube top....
[17:59:55] <Xteven> * Xteven is not making sense
[18:00:11] <Jymmm> stockings
[18:00:29] <Xteven> leadscrew nuts ?
[18:00:31] <Xteven> or so
[18:00:47] <SWPadnos> a double nut with preload
[18:01:00] <Xteven> that sounds a lot more scientificy
[18:01:07] <SWPadnos> I do that goodly
[18:01:13] <archivist> * archivist puts Jymmm in stocks and charges people to come and throw rotten vegetables at him
[18:01:25] <SWPadnos> * SWPadnos recoils at the thought
[18:01:34] <Xteven> http://images.machinedesign.com/images/archive/71976springjpg_00000049934.jpg
[18:01:35] <SWPadnos> * SWPadnos runs away in terror
[18:01:36] <Xteven> like that
[18:01:46] <SWPadnos> yes
[18:01:53] <roh> archivist nice idea.. let them throw leadscrews, and youre in business
[18:02:00] <archivist> yay
[18:02:04] <Jymmm> * Jymmm tosses archivist in the street corner and tells him "Work it baby, work it! Shake your money maker"
[18:03:04] <archivist> Jymmm, http://en.wikipedia.org/wiki/Stocks
[18:04:14] <Jymmm> archivist: http://tiny.cc/LSbo3
[18:19:16] <SWPadnos_> SWPadnos_ is now known as SWPadnos
[18:58:18] <Jymmm> I'm looking for nice clear definition of "microstepping" (verbiage wise), any suggestions? Just a one-liner or two would be fine.
[19:00:44] <anonimasu> microstepping is dividing a normal step into smaller pieces, allowing you to position in smaller increments
[19:01:21] <anonimasu> I were going to add a (which is typically 1.8 degrees)
[19:01:29] <Jymmm> ohhhh, that was niiiiice anonimasu =)
[19:01:58] <archivist> but due to internal magnetics the partial steps are not accurate divisions of a full step
[19:02:06] <anonimasu> you beat me to the second line :)
[19:02:14] <archivist> :)
[19:02:44] <archivist> thats the snake oil most dont see
[19:02:45] <Jymmm> I'm just trying to make a JS calculator, and thought it be nice to toss in a little description is all
[19:04:21] <anonimasu> indeed
[19:04:59] <frallzor> anyone in here using solidcam?
[20:17:47] <frallzor> is there some line-limit in emc? it woont show my model and paths in the preview
[20:17:50] <frallzor> *
[20:17:52] <frallzor> *wont
[20:18:24] <frallzor> seems to load all the code fine, but nothing shows
[20:18:55] <archivist> zoom right out
[20:19:02] <archivist> or in
[20:19:40] <archivist> Ive sometimes had to hunt for a dot or two when ive made a boob
[20:19:53] <frallzor> it wont show
[20:20:03] <frallzor> emc2 axis only
[20:22:03] <frallzor> and for some reason it wont obey my home axis for Z
[20:22:18] <anonimasu> if you use perspective view it should auto zoom to the extents of your code
[20:22:21] <frallzor> allways 0.500 or -0.500
[20:22:22] <anonimasu> or any other view
[20:22:47] <frallzor> nope, no model there
[20:22:59] <frallzor> just EMC2 AXIS that the software starts with
[20:24:41] <frallzor> but running it is no problem
[20:57:18] <frallzor> who in here had a G540 too?
[21:33:55] <ChanServ> [#emc] "This is the #emc channel - talk related to the Enhanced Machine Controller and general machining. Website: http://www.linuxcnc.org/, wiki at http://wiki.linuxcnc.org/"
[21:34:41] <SWPadnos> cool
[21:35:23] <Jymmm> SWPadnos: thought you might like that =)
[21:38:28] <ChanServ> [#emc] "This is the #emc channel - talk related to the Enhanced Machine Controller and general machining. Website: http://www.linuxcnc.org/, wiki at http://wiki.linuxcnc.org/"
[21:38:42] <Jymmm> ?
[21:38:49] <SWPadnos> the logger
[21:38:59] <Jymmm> ?
[21:39:12] <SWPadnos> disconnecting - I can't tell why it's doing that
[21:39:17] <Jymmm> ah
[21:40:02] <SWPadnos> I think the perl isn't so great, but I don't know enough perl to be able to tell
[21:40:11] <Jymmm> gitcha
[21:40:12] <SWPadnos> s/the perl/the code/
[21:40:14] <Jymmm> gotcha
[22:02:02] <EbiDK|AWAY> http://thedailywtf.com/Articles/Bourne-Into-Oblivion.aspx Ouch and DUH!!
[22:25:48] <frallzor> lets say you pause a job in emc, can you save it somehow and continue another day?
[22:31:30] <jepler> yay, 3 working servo axes
[22:32:01] <skunkworks> jepler: Way cool :)
[22:32:03] <geo01005> awesome jelper :)
[22:32:38] <frallzor> is it a bug that if I set my home axis on Z its allways 0.500 or -0.500? =)
[22:32:49] <frallzor> when its set to 0 in stepconf that is
[22:34:01] <Jymmm> And THIS is why I hate working IT... http://thedailywtf.com/Articles/Slow,-Difficult-to-Code,-and-Buggy.aspx
[22:34:16] <skunkworks> frallzor: http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?CoordinateSystems
[22:35:29] <frallzor> well IF my home axis is set to 0, shouldnt it be 0 when homed? =)
[22:35:59] <skunkworks> not if you have some offsets set.
[22:36:40] <frallzor> but if set like 10 as home, its 10
[22:36:47] <frallzor> but 0 is bugging for me
[22:38:21] <frallzor> ill try to play with settings some more
[22:42:15] <jepler> frallzor: stepconf changes the end of travel so that it is at least .01" (for inch machines) or .1mm (for metric machines) away from the home position
[22:42:43] <jepler> I can't explain where 0.500 inch or mm would come from, though
[22:46:32] <frallzor> noone can =)