#emc | Logs for 2010-08-22

[01:01:32] <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/"
[01:04:30] <skunkworks> eztam: hi
[01:16:06] <alex_chally> annnd my lathe stops feeding
[01:21:14] <cradek> "Core Cell chip extreme you've ever needed!"
[01:21:56] <cradek> (caption under a transparent-capsule thing logo when this motherboard boots)
[01:27:18] <skunkworks> fluffy
[02:24:40] <pcw_home> All this exciting stuff and I did nothing today except hang around with the grass-dogs http://filebin.ca/uwhdzk
[02:30:57] <cradek> looks like they want you to entertain them
[02:31:16] <cradek> "wonder what the two-legger does next"
[02:31:57] <pcw_home> I point out food to them so I'm an honorary sheep
[02:35:53] <skunkworks> so - does anyone know what the distance limit of single ended encoders is? and B) does anyone know a source for line drives?
[02:36:17] <skunkworks> I think we start losing postion at around 60ipm
[02:36:50] <skunkworks> we kinda thought we might have a problem with that. the distance is a good 15ft.
[02:41:10] <cradek> skunkworks: are you positive your 7i33 jumpers are set right?
[02:41:43] <skunkworks> yes - it is set for single ended. well - I will double check. but I am pretty sure.
[02:42:24] <cradek> when I was working on my (single ended) spindle encoder I scoped it at the 7i33. the roundoff is very apparent and it's easy to see when it'll all go wrong
[02:47:00] <pcw_home> Sometime 1K or so pullup resistors on ABI can help
[02:47:54] <pcw_home> (Sometimes)
[02:51:12] <pcw_home> 15 ft is a long way for single ended...
[02:53:55] <skunkworks> heh
[02:55:14] <skunkworks> well at 60ipm that is 60khz
[02:55:20] <skunkworks> did I do that right?
[02:56:23] <skunkworks> 60960 counts per inch. *60ipm/60sec/min?
[02:56:44] <pcw_home> Often single ended encoders just have the opto detector comparators (open collector with a pullup)
[02:56:45] <pcw_home> driving the lines so the rise time of the pullup resistor driving your cable capacitance will limit your max rate
[02:58:27] <pcw_home> 15 KHz
[03:06:11] <pcw_home> crosstalk could also be an issue depending on cable type (say 30 pF/ft = 450 pF = 1.5 usec glitch from one output driving low into a say 3K pullup on another output)
[03:06:13] <pcw_home> This could be mitigated by setting the encoder filter slower (You need to scope the signals to see whats going on)
[03:13:03] <skunkworks> I will have to play with it. the cable is a 4 conductor shielded with no twist
[03:13:26] <skunkworks> shield is hooked to the - on pin 1 iirc
[03:13:35] <skunkworks> of the 7i33
[03:16:14] <skunkworks> pcw_home: did you see this? http://www.youtube.com/watch?v=FgOqEz5Tk-Y
[03:18:17] <cradek> that's not really all that impressive until you notice it's a tenths indicator.
[03:19:14] <skunkworks> I was giggling when I saw how it was doing.
[03:19:28] <pcw_home> Yes, I did. Look really good especially since you are just starting to tune it up
[03:20:27] <skunkworks> cradek: I think I am getting what you were saying about tuning - if the ff1 is set to 1 and things are scaled right - the drive should do exactly what emc whats it to do without any exta tuning.
[03:20:38] <skunkworks> extra
[03:21:25] <skunkworks> emc doesn't have to do much extra work for the axis to follow.
[03:21:48] <skunkworks> compared to a voltage mode setup.
[03:21:49] <pcw_home> Yes, do as much as you can with the feedforward terms
[03:23:17] <pcw_home> Then the PID loop (with its limitations) has less to correct
[03:24:53] <cradek> I leave I at zero - if I have offset when stopped, I fix it with the amp's knob
[03:25:07] <skunkworks> are there line drivers out there? I am not finding anything. Not a popular product?
[03:25:23] <cradek> us digital makes one
[03:25:29] <cradek> it plugs into the back of their encoders
[03:25:53] <skunkworks> ah - ok. I think I ran across that - I didn't know what I was looking at - thought it was part of the encoder.
[03:26:15] <pcw_home> For long single ended cables (which I do not recommend) you would be better off with a twisted ground for each signal
[03:27:15] <pcw_home> Line driver is Just a 26LS32+VCC bypass on a PCB
[03:28:40] <pcw_home> If you can make PCBs thats about as easy as they get
[03:28:48] <skunkworks> heh - I will look into it.
[03:28:51] <skunkworks> thanks
[03:29:13] <skunkworks> does the a(not) actually go negative then?
[03:29:26] <skunkworks> -5v
[03:29:37] <pcw_home> no
[03:30:50] <pcw_home> signals are like TTL levels just differential
[03:30:51] <pcw_home> (I meant 26LS31)
[03:31:07] <skunkworks> heh. well I must be dense tonight. ;) I don't see why it would be much better. - just that your referencing a - a(not) instead of a to ground?
[03:31:42] <skunkworks> it has been a long day :)
[03:33:14] <pcw_home> the receiver looks at the difference between the signals
[03:33:15] <pcw_home> so even a /1/2V differenec will be detected properly with common mode of -7 to +12 or so
[03:35:48] <pcw_home> induced noise will be induced to both A and 'A almost equally (since they are a twisted pair) so our little differential TTL signals
[03:35:49] <pcw_home> can be detected with 10 times as much common mode noise as signal
[03:36:18] <skunkworks> ah. thank you
[03:37:17] <pcw_home> whereas 1.5V of common mode noise will put your single ended interface out of operation
[03:38:29] <KimK> For a convenient differential driver (or receiver), I'd look at USDigital: http://www.usdigital.com/products/interfaces/encoder/cable-drivers/ea/ spec sheet at: http://www.usdigital.com/assets/general/104_ea_datasheet_0.pdf The CUI AMT10x series encoders have a "cable lump" driver/rcvr too, hang on...
[03:39:25] <KimK> OK, here's the driver, still looking for the receiver... http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=102-1787-ND
[03:40:18] <KimK> Maybe they don't supply the receiver because it's "not their problem"?
[03:40:19] <skunkworks> don't need a reciever - got a mesa 7i33
[03:40:26] <KimK> Ah, excellent!
[03:40:30] <skunkworks> Hi kim!
[03:41:12] <pcw_home> Hey a dip 26LS31 some hotmelt and shrink tubing and youv;e got a cable lump driver
[03:41:23] <skunkworks> KimK: one more time.. ;) did you see http://www.youtube.com/watch?v=FgOqEz5Tk-Y
[03:41:40] <KimK> Yeah, that's all they are. But they did all the work, lol.
[03:41:55] <skunkworks> pcw_home: I would have no problem doing that :)
[03:42:31] <skunkworks> what do people use for cable then? seems shielded cat5 would work well.
[03:42:53] <skunkworks> 3 pairs for abz and one for +/-
[03:42:59] <SWPadnos> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=296-14971-1-ND
[03:43:12] <SWPadnos> that's a transceiver with 2 ins and 2 outs
[03:43:31] <SWPadnos> there are probably others that have just ins or outs
[03:43:31] <pcw_home> I like soldering...
[03:43:32] <pcw_home> Isn't cat 5 usually solid?
[03:43:59] <skunkworks> yes - but remember my servos don't move
[03:44:09] <SWPadnos> shielded cat5 only has an overall shield I think, not per pair
[03:44:33] <skunkworks> oh - I need a shield per pair. that seem expensive ;)
[03:44:46] <SWPadnos> I don't know that you do, but then again ...
[03:44:59] <pcw_home> Doubt you need a shield per pair
[03:45:00] <alex_chally> pcw_home, they do make stranded cat 5 for motion
[03:45:12] <KimK> Or use a bunch of runs (if you already have the CAT5)
[03:45:37] <pcw_home> OK I know they make solid and stranded plugs
[03:46:27] <SWPadnos> pcw_home, do you know of a good isolated differential xcvr chip?
[03:46:53] <KimK> alex_chally: That's exactly what USDigital uses for their (finely stranded) encoder cable. It's even color-coded the same way, white-blue/blue-white, etc.
[03:47:13] <pcw_home> SWPadnos: Analog devices make some
[03:47:31] <SWPadnos> the adum1100 series maybe?
[03:47:39] <SWPadnos> (or were those the little A/D's?)
[03:48:04] <pcw_home> Dont know off hand look at their interface section
[03:48:21] <SWPadnos> ok, thanks for the pointer
[03:48:53] <pcw_home> they make some with isolated power as well
[03:50:24] <SWPadnos> yeah. I think I didn't find anything great, so I ended up with one of those little 1W DC:DC isolated power supply chips plus an isolated single ended buffer, plus a differential transceiver (powered by the isolated supply)
[03:50:39] <SWPadnos> more complex than a single chip, that's for sure :)
[03:51:29] <KimK> skunkworks: No, I had not seen your video. So that's 0.100" of motion? Nice!
[03:52:13] <skunkworks> no - .05" and the minor divisions are .0001
[03:53:06] <pcw_home> The neat thing about Analogs isopower chips is the power supply has amazingly low capacitance across the isolation
[03:53:08] <pcw_home> the bad thin is that the power supplys are quite inefficient
[03:53:12] <KimK> OK, 0.050", then I stand corrected. I thought it was .010" per rev and 10 revs.
[03:53:54] <SWPadnos> yeah, I like the integrated power supply
[03:54:06] <skunkworks> as cradek pointed out - it overshoots a half a tenth. I am still giggling
[03:55:22] <KimK> Now this is just on encoders, right? You haven't (yet) tried to bring back the Accupins, have you?
[03:55:30] <skunkworks> no - just encoders
[03:55:45] <KimK> OK
[03:55:58] <skunkworks> accupins are way down the road
[03:56:34] <skunkworks> ok - I think it is time for bed. I am starting to see double
[03:56:49] <skunkworks> Thanks for all the help guys. It's moving!
[03:56:57] <KimK> Ha, OK, goodnight. Glad i got to hear the good news.
[03:57:43] <pcw_home> 'nite again congrats on first controlled axis movement!
[03:58:13] <KimK> (with a Mesa 7i33!)
[03:58:23] <skunkworks> heh - the first 2 tries where not controlled... ;) I inverted the tach back to the emp. run away - run away!
[03:59:16] <pcw_home> I assume you did this with the belts unhooked!
[04:00:56] <KimK> * KimK guesses that skunkworks unhooked the belts for the *second* try, lol
[04:01:52] <KimK> Can't fool skunkworks more than once!
[04:02:16] <KimK> Ah, he's gone, lol
[04:03:34] <pcw_home> Be quite treat to see that really old iron doing useful work again
[04:04:09] <pcw_home> and with that I'm gone as well
[07:00:32] <root> root is now known as Guest96675
[07:01:44] <Guest96675> Guest96675 is now known as new2emc
[08:28:55] <Fox_M|afk> Fox_M|afk is now known as Fox_Muldr
[12:40:44] <pingufan> Hi, I have to build a new breakoutboard. Gecko uses a HCPL-2531 optocoupler, it is very fast (1 MHz), but I would have to buy some. What I have at hands is a Sharp PC123 coupler. Will it be good enough for steper driving?
[12:43:35] <awallin_> how fast is the PC123, and what is the max step rate you are going to be using?
[12:44:43] <pingufan> I read about Cuttoff frequency of 80 kHz
[12:47:01] <awallin_> that doesn't sound very fast, if you are going to generate steps at 10 or 20kHz
[12:47:23] <awallin_> but if the gecko already has an optoisolated input, why do you need isolation in the breakout board?
[12:49:05] <pingufan> Gecko uses a breakout board in the G540 drive. The G540 includes four G250 modules. I use the G251 which is almost the same and also has no opto-isolators inside.
[12:50:59] <pingufan> How fast can a parallel port be at all? Parallel ports never were really fast...
[12:51:19] <awallin_> 20khz if you are lucky
[12:52:22] <pingufan> So why should I worry about 80 kHz to be "slow" ? ;)
[12:52:51] <awallin_> it might work ok
[12:53:19] <pingufan> Very good chances, or bad chances?
[12:54:02] <awallin_> if the PC123 datasheet has a picture of a 80kHz square wave and it looks like a square wave, not a sine wave, then you are ok
[12:54:27] <pingufan> Ah. Ok. Ill look on that.
[12:55:16] <pingufan> Are Geckos very sensible in the signal?
[12:55:42] <awallin_> I don't think they are very picky
[12:57:04] <pingufan> So, as I am surely below 20 kHz (I use a VIA C7 CPU with 1000 or 1500 MHz), the signal will surely be better as at 80 kHz.
[12:58:30] <IchGuckLive> Hi all from sunny germany Thunderstorm ahad
[12:59:24] <pingufan> hi!
[13:45:34] <IchGuckLive> i made a final and upload the new grid generator pleas feel free for testing -> http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Simple_EMC_G-Code_Generators#Grid_Rectangular_Circular_SpiderNet_G_code_Generator
[13:51:34] <IchGuckLive> and here is the video of testing http://www.youtube.com/watch?v=QtCabDDm_EI
[14:02:58] <awallin_> IchGuckLive: is it only for positioning holes for drilling? or for actually milling the grid?
[14:07:09] <IchGuckLive> milling the grid offcause
[14:07:39] <IchGuckLive> you can ad a drill at all pints by adding G81
[14:07:51] <IchGuckLive> B)
[14:08:21] <IchGuckLive> so thunder starts now by i got to safe the satelite dish the solarsystem and so on !!!!!
[14:54:11] <eztam> hi
[14:55:30] <Mendelbuild> hi
[14:57:48] <eztam> hiho mendel
[14:58:03] <Mendelbuild> whats up ?
[14:59:09] <eztam> lazy day today
[14:59:16] <Mendelbuild> well yeah sundays
[15:00:09] <Mendelbuild> just the usual round on ebay here
[15:00:10] <eztam> where are u from ?
[15:00:17] <eztam> hehe
[15:00:21] <Mendelbuild> norway
[15:00:24] <eztam> here hannover/germany
[15:00:47] <Mendelbuild> ah :)
[15:01:37] <Mendelbuild> i am looking for some proper bearings and ballscrews right now
[15:02:09] <eztam> ballscrew - as a leadscrew ?
[15:02:21] <Mendelbuild> yeah
[15:02:51] <Mendelbuild> gotta start somewhere
[15:03:14] <eztam> i am thinking of adding encoders to my machine
[15:03:44] <Mendelbuild> ah already got a working mill ?
[15:04:56] <eztam> yep
[15:05:17] <Mendelbuild> nice, buildt yourself ?
[15:05:21] <eztam> nope
[15:05:32] <eztam> selfbought ;)
[15:05:37] <Mendelbuild> lol
[15:05:48] <eztam> hehe
[15:09:41] <eztam> do you want to build a machine from scratch ?
[15:10:18] <Mendelbuild> yeah ill give it a try
[15:10:45] <Mendelbuild> pretty sure it will take time
[15:10:45] <eztam> challenging job
[15:11:02] <eztam> a year or something
[15:12:34] <Mendelbuild> hoping to be able to make it in less time than that
[15:12:50] <Mendelbuild> last project took 3 months
[15:12:54] <eztam> ok
[15:13:41] <Mendelbuild> its a matter of getting cash in fast enough so the build doesent stop:P
[15:13:53] <eztam> hehe
[15:15:19] <Mendelbuild> got some plans from rockcliff
[15:15:30] <Mendelbuild> pretty straight forward stuff
[15:15:39] <eztam> ah ok
[15:15:43] <eztam> good idea
[15:15:52] <eztam> not to invent the wheel a second time
[15:16:21] <Mendelbuild> i will make another later in aluminum
[15:16:42] <Mendelbuild> but the costs was huge for that one
[15:16:57] <awallin> what kind of machine are you building?
[15:17:14] <Mendelbuild> awallin: rockcliff for now
[15:17:22] <eztam> mine is a proxxon mf70
[15:18:05] <awallin> ok so it's a router made of MDF...
[15:18:37] <eztam> hehe
[15:18:38] <eztam> nope
[15:18:48] <eztam> wait ill fetch a photo
[15:18:56] <Mendelbuild> neat little thing that proxxon
[15:19:23] <eztam> yep
[15:19:38] <eztam> its big enough for my purposes
[15:19:45] <Mendelbuild> so its a manual mill converted to cnc ?
[15:19:54] <eztam> exactly
[15:20:07] <Mendelbuild> have you done any estimates on the total ?
[15:20:28] <eztam> 1000euros
[15:20:35] <eztam> for the whole thing
[15:20:43] <Mendelbuild> not bad :)
[15:20:55] <eztam> hehe
[15:22:17] <Mendelbuild> i figured out it was best to build something basic first before i take on the task with the metal milling process
[15:22:48] <Mendelbuild> wouldnt like to crash that one because of lack of experience
[15:23:27] <eztam> crazy think
[15:23:48] <eztam> -k+g
[15:25:07] <Mendelbuild> ofcourse im not going 100% with the plans
[15:25:07] <eztam> i thought in getting a manual mf70 and a cnc kit separetly
[15:25:26] <eztam> but i deciced to get a the ready made one
[15:25:34] <eztam> decided
[15:25:59] <Mendelbuild> so it was more expensive then because it was readymade
[15:28:11] <eztam> 200euros more
[15:28:38] <eztam> but i was worth it because i lack the experience
[15:28:56] <eztam> maybe next time
[15:30:44] <Mendelbuild> yeah i buildt a reprap mendel before so i am familiar with some of it
[15:31:01] <eztam> cool stuff a reprap
[15:31:56] <eztam> i use my machine for doing pcb engraving
[15:32:10] <Mendelbuild> ah :)
[15:32:27] <eztam> just for prototypes
[15:33:02] <Mendelbuild> havent etched pcbs in 15 years, i buildt the electronics for the reprap myself but i bought PCB readymade
[15:33:15] <eztam> hehe
[15:33:47] <Mendelbuild> will probably get a chinese board for the mill
[15:34:16] <eztam> servos or steppers ?
[15:34:25] <Mendelbuild> nema 23's i think
[15:34:38] <eztam> ok
[15:35:11] <Mendelbuild> have to keep the cost down for this "preview" build
[15:35:40] <Mendelbuild> mostly to learn the basics of wood milling and how to set up the electronics
[15:35:42] <eztam> do you do the build for yourself ?
[15:35:52] <Mendelbuild> yeah
[15:36:48] <Mendelbuild> no one else here have a clue what it is and doesent care about knowing it it seems
[15:37:06] <eztam> hehe
[15:37:14] <Mendelbuild> my friends are just saying "huh whats that CNwhat?"
[15:37:18] <eztam> sounds somewhat lonely
[15:37:27] <Mendelbuild> nah ;)
[15:39:02] <eztam> here its close the same
[15:39:07] <eztam> thing
[15:39:55] <Mendelbuild> its first when the stuff is finished ppl realized what its all about
[15:40:09] <eztam> thats true
[15:41:38] <Mendelbuild> I enjoy the build/think process more than the use ;)
[15:42:15] <eztam> hehe
[15:43:53] <eztam> you are a real inventor
[15:43:55] <eztam> i guess
[15:47:57] <eztam> i need to go
[15:48:00] <eztam> see ya
[16:12:44] <IchGuckLive> im back after a heavy thunderstorm here in Germany
[16:19:14] <IchGuckLive> awallin: ?
[16:21:59] <IchGuckLive> Jymmm: ?
[16:22:15] <Jymmm> ?
[16:22:32] <IchGuckLive> here is the grid -> http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Simple_EMC_G-Code_Generators#Grid_Rectangular_Circular_SpiderNet_G_code_Generator
[16:22:43] <IchGuckLive> can you check if this works for you
[16:23:35] <Jymmm> The link works.
[16:24:07] <IchGuckLive> http://www.youtube.com/watch?v=QtCabDDm_EI
[16:24:14] <IchGuckLive> here is the test video
[16:25:19] <IchGuckLive> Jymmm: python file in axis? for you to
[16:25:40] <Jymmm> IchGuckLive: I don't have a emc setup here at the moment.
[16:25:48] <IchGuckLive> ok
[16:26:23] <IchGuckLive> i only got it run on lucid in simulation not RTI mode
[16:27:51] <IchGuckLive> anyone here than can check this script in Realtimekernel on axis emc?
[17:59:39] <IchGuckLive> so i go to bed its late here
[18:12:54] <ichudov> Is there some purpose made preprocessor for EMC2 G-code.
[18:14:52] <alex_chally> ichudov, there is one that works, but I can't for the life of me remember
[18:15:01] <alex_chally> I *think* it was either the fanuc or fidal one
[18:15:48] <ichudov> What I mean is, say, read G code, and in addition do some macros, or call truetype-tracer to get its output etc. I am thinking about tasks like creating a panel, with cutouts and numbers engraved.
[18:20:58] <alex_chally> ichudov, have you looked at he g-code tools on the emc wiki?
[18:21:12] <alex_chally> ichudov, http://wiki.linuxcnc.org/emcinfo.pl?Simple_EMC_G-Code_Generators
[18:21:31] <ichudov> lemme look
[18:23:28] <ichudov> alex_chally: thanks, I will look. What I was looking is a preprocessor, from which I could invoke other generators.
[18:25:54] <ichudov> gotta go, talk to you later
[20:03:29] <awallin> has anyone built something like this? http://www.youtube.com/watch?v=a2rM5Zy5T5Y
[20:03:35] <awallin> and used emc2 to control it?
[20:05:51] <awallin> could it be simulated with vismach?
[20:08:31] <cradek> I think fenn had a hexapod vismach model
[20:08:35] <cradek> maybe it's even in git - not sure
[20:09:12] <awallin> I need to learn how to do that then, with some custom kinematics...
[20:12:20] <awallin> http://fennetic.net/bfi/hextatic.jpg
[20:13:23] <awallin> http://fennetic.net/bfi/hexagui.jpg
[20:13:35] <awallin> the second image is vismach, I guess?
[20:13:45] <cradek> yes
[20:58:25] <awallin> well this is fun: http://www.youtube.com/watch?v=Du2f-EUDqio
[22:17:53] <skunkworks> KimK: thanks for the link of the CUI AMT10x series encoders have driver/rcvr. I think that is what we are going to try
[22:18:04] <skunkworks> cheap and easy :)
[22:21:18] <KimK> skunkworks: You bet. We're going to use at least one here to test a CUI AMT10x against a USDigital of exactly the same resolution. At least that's on our list of things to do, lol. But right now we do seem to have bigger fish to fry.
[22:22:44] <KimK> Good to see the K&T moving. X & Y both, or just one? I think you said Z was a different situation?
[22:23:40] <Fox_Muldr> Fox_Muldr is now known as Fox_M|afk
[22:51:58] <skunkworks> KimK: z is pretty close to moving
[22:52:15] <skunkworks> y still need a bit of enginering but not a big deal
[23:17:04] <skunkworks> KimK: http://www.electronicsam.com/images/KandT/conversion/servo/belts.jpeg
[23:17:09] <skunkworks> that is x and z
[23:19:08] <KimK> That's some big iron.
[23:21:00] <skunkworks> :) the only way to go?
[23:21:20] <skunkworks> you where standing on that end when you were down
[23:21:46] <skunkworks> (they were not mounted yet)