#emc | Logs for 2010-12-17

[00:05:06] <theorb> theorb is now known as theorbtwo
[02:17:44] <elmo40> anyone use an internet stick with Linux?
[09:17:32] <psha> hi
[09:17:32] <the_wench> hello psha, you have a question?
[09:45:58] <micges_work> hi
[09:45:58] <the_wench> hello micges_work, you have a question?
[09:46:09] <micges_work> I like him ;)
[09:58:01] <archivist> her!
[10:02:17] <micges_work> sorry :D
[11:47:38] <jthornton> hello
[11:47:38] <the_wench> hello jthornton, you have a question?
[11:47:53] <jthornton> nope just wanted to see the_wench
[12:35:42] <dimas_> huh
[13:18:23] <Jymmm> * Jymmm lol @ jthornton
[13:20:25] <the_wench> /me laffs at jymmm
[13:23:02] <Jymmm> jthornton: Per your request... http://tinyurl.com/TheWench
[13:32:38] <SWPadnos> take two, they're - err - well just take two
[13:33:24] <Jymmm> three would be beter
[13:33:41] <SWPadnos> actually, I'm still trying to figure out how to use two at once :)
[13:34:02] <Jymmm> lol
[13:34:19] <Valen> SWPadnos: the method is for them to use each other, then you join in
[13:34:19] <SWPadnos> I guess you need a spare, in case one gets sick
[13:34:28] <SWPadnos> hmmm. well that could work
[13:37:21] <Valen> SWPadnos: it does
[13:37:29] <Valen> but thats a story for another #
[13:37:34] <SWPadnos> uh, yeah
[13:37:42] <Valen> ;-P
[13:38:02] <Valen> * Valen has made a USB enabled flashing light today
[13:42:00] <Valen> got end mill? http://cgi.ebay.com.au/CoHSS-endmill-slot-dill-50mm-1-threaded-shank-Sutton-/320620249887?pt=LH_DefaultDomain_15&hash=item4aa674c31f#ht_500wt_1156
[13:50:04] <skunkworks> shell mill? http://www.electronicsam.com/images/KandT/conversion/Shellmill.JPG
[13:50:06] <skunkworks> ;)
[13:50:51] <fragalot> Hey - if any of you mill PCB's, what cutting speed would you recommend for a 0.1, 0.2 and 0.3mm V-bit ?
[13:51:13] <fragalot> 18000rpm
[13:52:09] <Jymmm> speed of light in a vacuumm ^4
[13:53:36] <fragalot> so.. F800? :P
[13:53:46] <fragalot> (since that's my machine's limit)
[13:59:43] <SWPadnos> what kind of cut (per "tooth") do you think a 0.1mm bit can handle?
[13:59:51] <SWPadnos> I'd say not much
[14:01:35] <cradek> what do you mean .1 mm V bit? what part of it is .1 mm?
[14:02:00] <i_tarzan> nobody uses 0.1mm dia bits
[14:02:07] <SWPadnos> heh
[14:02:17] <SWPadnos> zero-point cutting
[14:02:48] <cradek> I'm picturing a V bit that comes to a sharp point. Given the right depth this can leave a .1 mm trough.
[14:03:15] <cradek> when I cut PCBs I cut about .006 in deep and get a trough about .008 in wide
[14:03:29] <cradek> that's with a 60 degree V tool
[14:04:10] <cradek> I use a feed of .001 inch per rev (not sure it makes sense to talk about 'teeth' at that size)
[14:04:40] <SWPadnos> yeah, I assumed that a small V bit like that would be an engraving bit, with one "tooth"
[14:05:24] <cradek> mine actually do have two 'teeth' - they make dust as you cut - it's not just a displacement process
[14:06:34] <fragalot> yeah, 60 degree V-bit is what I meant
[14:06:50] <fragalot> SWPadnos: it is
[14:07:00] <fragalot> no idea what their proper name is :/
[15:20:38] <AR_> finally trying to build a decent machine
[15:20:54] <AR_> trying to fit all parts together using wood first, then ill try to build a steel frame
[15:35:05] <grommit> I have a breakout board with a 78M05 regulator on it. It wants me to apply 9-24v to it and it has an output pin to pass the regulated 5v on to another board or whatever. I (currently) have a 5V supply only. Does anyone know if I feed 5v into the output pin (in order to bypass the regulator) if I will burn it up? Of course the manufacturer of board says never do this, but I am wondering...
[15:35:07] <grommit> ...if the chip can handle it. I looked at the Fairchild data sheet but don't see anything useful there about this...
[15:35:29] <cradek> is your 5v regulated?
[15:35:34] <grommit> yes
[15:35:56] <cradek> you could just desolder or snip off the 7805...
[15:36:24] <psha> grommit: hi, how's your local summit? :)
[15:36:30] <grommit> true, but it would be nice to leave it, if it would survive....
[15:36:52] <grommit> I didn't end up presenting as other talks ran on. I should be able to do it at the next one (next month).
[15:37:21] <cradek> it'll probably be fine - and if not, they're a common part
[15:37:37] <grommit> good point. I can just replace it if it fries...
[15:39:05] <pcw_home> If your external 5V is a little higher (0 to 300 mV or so) than the 78M05s, output voltage there would be no problem
[15:39:07] <pcw_home> but if your external 5V is lower the 78M05 will try and power the external 5V supplies load
[15:43:56] <pcw_home> Oh I didn't see the you want to run it with no unregulated in (safest to put a 1N4001 diode across the 78M05 in this case, anode to 5V cathode to unregulated in)
[15:51:23] <atmega> dilettante
[15:51:34] <atmega> <wfc>
[16:39:25] <grommit> PCW: Still here?
[16:41:58] <grommit> My 5v supply is regulated. I have it connected to the output of the 78M05 and it seems to be fine. The 78M05 is passing current back through itself, I measure 3.9V on the input pin and it is lighting the input LED (how convenient :-). Nothing has smoked yet.
[16:50:37] <pcw_home> I think its only a problem if theres a big input capacitor so the 5V charges the input capacitor through the 78M05 backwards and the peak current is too high
[17:38:02] <alex_joni> is it me, or does flash _really_ suck on 10.04 ?
[17:39:54] <archivist> really suck for me on 64bit
[17:40:07] <cradek> works fine for me
[17:40:31] <archivist> its less bad on this p4 box im on now
[17:48:48] <alex_joni> cradek: it's not that it isn't working, it's just using 50% more processor and feels a bit more sluggish than on doze
[17:49:16] <cradek> oh, I wouldn't know about that comparison
[17:49:23] <alex_joni> using on both
[17:49:54] <alex_joni> * alex_joni has to read into power management as well
[17:50:16] <alex_joni> the battery I got is ok for about 4h on doze, only 2h on 10.04.1
[17:51:27] <andypugh> Is that with RTAI over-riding the power management?
[17:52:10] <alex_joni> nopee
[17:52:14] <alex_joni> stock 10.04.1
[17:52:59] <alex_joni> I did change the governor, and that helped a bit
[18:14:22] <skunkworks> governor?
[18:16:17] <alex_joni> # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
[18:16:46] <skunkworks> neat
[18:19:07] <alex_joni> "Anyway, for recent enough Intel CPU, ondemand is the one recommended for power efficiency (over userspace, and even over "powersave") by the Intel's kernel developer Arjan van de Ven"
[18:19:30] <skunkworks> that is what my laptop defaulted to.
[18:25:48] <andypugh> Almost perfect as a spindle encoder ring for a lathe or mlll. (Just add hall sensors)
[18:25:50] <andypugh> http://cgi.ebay.co.uk/Peugeot-BNIB-207-307-407-ABS-ESP-Speed-Sensor-Ring-/270676759555
[18:26:37] <andypugh> I didn't know that they used magnetic ring for ABS (I did know they used them for crank position)
[18:54:15] <grommit> anyone know where "TP1" on a Gecko 340X is located? The instructions use this nomenclature for the motor calibration procedure but we can't find TP1 anywhere and none of the Gecko docs seems to show it....
[18:58:31] <atmega> how about: http://www.geckodrive.com/upload/G320TestPoints.pdf
[19:01:14] <grommit> That is the older one, the 320X doesn't look anything like it and we can't find anything that even looks similar....
[19:01:57] <atmega> call them and ask?
[19:03:16] <atmega> I obviously have no clue, but that would be my first choice.
[19:06:36] <grommit> yep, that is what we are doing. thanks.
[21:59:53] <andypugh> quiet tonight
[22:10:09] <Jymmm> lil bit
[22:16:56] <mikeggg> * mikeggg hums purple rain
[22:26:07] <Jymmm> * Jymmm invites mikeggg to the 21st Century
[22:26:47] <SWPadnos> party like it's 1999
[22:28:11] <Jymmm> Prince' limo was purple and wanted his cell antenna to be too. One guy told him it required special paint and that it would cost $700. he paid.
[22:32:21] <juri_> makes sense to me.
[22:42:01] <The_Ball> andypugh, brilliant idea for a spindle encoder
[22:42:24] <andypugh> Aye, nice big hole through the middle.
[22:42:58] <andypugh> I am not sure how much the sensors cost.
[22:46:16] <SWPadnos> andypugh, I know Ford calls them "tone rings" for ABS use
[22:46:29] <SWPadnos> a friend had one break on his Escape hybrid
[22:47:00] <andypugh> The Ford ones I have seen are toothed wheels. The eBay one is a magnetic ring.
[22:47:30] <SWPadnos> oh hmm. I never actually saw his when it was repaired - the vehicle was under warrantee still :)
[22:47:45] <andypugh> I am amused by the name "tone ring", that's very Hammond Organ. http://en.wikipedia.org/wiki/Hammond_Organ
[22:48:07] <atmega> today's xkcd.com is amusing, if you are in to that sort of thing.
[22:49:50] <andypugh> I am, and was
[22:50:10] <JT-Shop> * JT-Shop takes a short break from bisecting the tractor
[22:50:25] <andypugh> I missed another Wohlhaupter boring head on that eBay.
[22:50:44] <andypugh> They seem to go for £200 (and are probably worth every penny)
[22:51:16] <andypugh> I have a really neat idea for an electrically controlled boring head.
[22:51:35] <JT-Shop> hows that?
[22:51:50] <andypugh> (They already exist, it is the mode of driving it that I consider clever)
[22:52:42] <andypugh> Are you familiar with the automatic boring heads, where you hold a ring to advance them, without stopping the spindle?
[22:52:59] <JT-Shop> I like the way some e-bay add are so misleading "Neise UFB-4 Wohlhaupter Style"
[22:53:10] <JT-Shop> no, I've not seen one
[22:53:40] <JT-Shop> is that for facing only that you do that?
[22:54:56] <andypugh> Facing you tend to use an anti-rotation bar. They advance to the stop, then rapid-retract.
[22:55:33] <andypugh> For boring you bacj them out, hold the ring for the right number of clicks, then run through the bore again
[22:56:25] <andypugh> My idea is to make the ring the stator of a stepper. And also the wheel of a magnetic encoder.
[22:56:40] <andypugh> (rotor of a stepper, I mean)
[22:57:55] <andypugh> Software simply keeps the stepper and encoder in synch to produce no net ring rotation, but adds or subtracts a bit when you do want relative motion.
[22:59:11] <andypugh> (And there goes any hope of patenting the idea now it is in the public domain)
[22:59:24] <JT-Shop> LOL
[23:00:06] <andypugh> I am semi-serious, I think it is the most patentable idea I have had
[23:00:26] <JT-Shop> I was just laughing about the public domain part
[23:00:59] <JT-Shop> what kind of application do you use that type of boring bar for?
[23:01:54] <andypugh> Which type? The existing sort or the hypothetical CNC sort?
[23:02:24] <JT-Shop> the CNC sort
[23:02:34] <andypugh> Tapered bores?
[23:02:51] <JT-Shop> or one off's?
[23:02:58] <andypugh> Aye
[23:03:30] <JT-Shop> which is mostly what I do but don't need that much precision for the most part for what I make
[23:05:21] <andypugh> I use my conventional boring head a lot for bearing housings. And get really bored of stopping the spindle, rotating to where the adjuster is, and tweaking some more
[23:05:22] <JT-Shop> * JT-Shop goes back to tractor disassembly
[23:06:15] <andypugh> Some seriously big stuff being made here
[23:06:17] <andypugh> http://www.youtube.com/watch?v=sRXFkH3-iAk
[23:09:59] <AR_> anyone know how to control DC motors with tachometers?
[23:10:10] <AR_> is it common/easy?
[23:10:47] <andypugh> It's certainly common
[23:11:42] <AR_> harder than steppers though I assume as it needs to send the tach pulses back to the computer?
[23:12:35] <andypugh> Generally speaking the tach only goes to the drive, and the computer is uninvolved
[23:14:04] <AR_> ah, I see, so the computer sends pulses to the driver, like a stepper driver
[23:14:07] <andypugh> From what I have heard here and on the mailing list you only bother with tachs (or simulate them in software) to keep velocity-feedback drives happy.
[23:14:16] <AR_> ah
[23:14:41] <andypugh> Otherwise you might as well run the drives torque-mode, ignore the tachs, and close the loop in EMC
[23:15:16] <AR_> are drivers expensive or easy to build?
[23:15:54] <andypugh> There probably are step/dir drives which close their loop with a tach. You would hope to have both halves in that case
[23:16:07] <andypugh> Depends
[23:16:24] <andypugh> What do you actually have?
[23:16:53] <AR_> what do you mean
[23:17:57] <andypugh> If you describe the hardware, we can probably advise how best to make it work.
[23:18:44] <andypugh> Oooh! Neat! http://www.youtube.com/watch?v=tu2GFst6Ehs&NR=1
[23:19:07] <AR_> it is a DC motor with + and - leads, and an encoder/tach on top with 4 wires coming out
[23:19:18] <SWPadnos> I don't know that any step/dir drive would use a tach, unless it's a drive that has the option of running in velocity or "smart" position mode
[23:19:34] <SWPadnos> an encoder/tach with 4 wires is most likely just an encoder
[23:19:49] <AR_> i opened it up and it is a disk with slits in it
[23:19:50] <SWPadnos> since an encoder needs power (2 wires) and A and B quadrature outputs
[23:19:53] <andypugh> Do you have the matching drive? If not I would ignore the tach
[23:19:55] <SWPadnos> that's an encoder
[23:20:05] <AR_> ah
[23:20:10] <AR_> no i dont have a driver
[23:20:20] <andypugh> Current? Voltage?
[23:20:21] <SWPadnos> a gecko drive will work
[23:20:30] <SWPadnos> if you want step/dir
[23:20:31] <AR_> gecko is too expensive for me :P
[23:20:33] <andypugh> Or a Pico, or Mesa
[23:20:44] <SWPadnos> also too expensive ;)
[23:21:09] <SWPadnos> if you look on the wiki, you should find some information on a simple H-bridge design
[23:21:10] <AR_> so it is more complicated than a stepper driver or what?
[23:21:11] <andypugh> Parport PWM and power Mosfets then
[23:21:14] <AR_> oh ok
[23:21:20] <AR_> lol
[23:21:38] <SWPadnos> it's not likely to work very well with a small motor, since the response speed of the motor will be pretty quick
[23:21:55] <andypugh> Actually, it is elecronically easier than a stepper, and the rest is just sotfware
[23:21:55] <AR_> 12V
[23:22:04] <AR_> oh really?
[23:22:12] <SWPadnos> (ie, the motor bandwidth is high, so the control bandwidth needs to be higher, which requires a faster control loop, which the PC may not be able to handle
[23:22:14] <SWPadnos> )
[23:22:31] <andypugh> Aye, you might need to add a flywheel :-)
[23:22:34] <SWPadnos> yeah, a stepper needs twice the power electronics since it has two coils
[23:22:59] <SWPadnos> but it doesn't need the encoder, so it's often less expensive overall
[23:23:01] <AR_> the motors are Buhler A-3140-0864-1
[23:23:07] <AR_>
[23:23:10] <AR_> 12V
[23:23:20] <AR_> and there is also "256/95" on the label
[23:23:22] <AR_> is that important
[23:23:52] <SWPadnos> http://mesanet.com/
[23:24:22] <SWPadnos> 7i30 plus 7i43 plus 7i47 would give you control for 4 motors with encoder inputs, plus another 24 I/O
[23:24:42] <SWPadnos> the 7i30 is actually the power electronics for 4 motors
[23:24:52] <SWPadnos> 3A limit per motor though
[23:25:13] <andypugh> You could possibly skip the 7i47, and wire encoders direct to the 7i43
[23:25:22] <andypugh> (I do)
[23:25:33] <SWPadnos> the encoders go to the 7i30, the 7i47 is for isoaltion of other I/O
[23:25:39] <SWPadnos> isolation
[23:26:28] <andypugh> Ah, OK, I am fuzzy on part numbers
[23:26:40] <SWPadnos> me too. I was looking at the site :)
[23:27:36] <JT-Shop> seriously big machines holding the boring bars
[23:27:41] <andypugh> If you skip the isolated IO we just spent $180 of your money.
[23:28:27] <AR_> lol
[23:28:31] <andypugh> But saved you months of messing about. And the parts to build your own p-port based system wouldn't be cheap
[23:28:34] <SWPadnos> it's a steal :)
[23:28:43] <andypugh> He's right
[23:28:54] <AR_> ok
[23:28:55] <SWPadnos> and it wouldn't work for more than 2 motors, due to the need for both input and output for each motor
[23:28:55] <AR_> well
[23:28:58] <AR_> i only have 2
[23:28:59] <AR_> lol
[23:29:00] <SWPadnos> maybe 3
[23:29:01] <JT-Shop> we use to face the gun mount with a homemade facing bar from a piece of H beam and all thread with a star wheel at the end to move the cutter just a bit each pass about 8' across
[23:29:18] <andypugh> Do you want a fun, educational project, or computer controlled motors in a hurry?
[23:29:23] <SWPadnos> ok, you can run 2 motors with the parport, but you need additional hardware
[23:29:30] <AR_> is it possible for emc to control a machine with 2 DC motors and 1 stepper?
[23:29:31] <AR_> lol
[23:29:36] <SWPadnos> yes
[23:29:40] <JT-Shop> yea
[23:29:51] <AR_> well maybe ill look into it
[23:30:16] <SWPadnos> though you're pushing the input capacity of a parallel port with that, since there are only 17 I/Os, and they're in a specific input/output arrangement
[23:30:25] <andypugh> I guarantee you can't build stuff good enough cheaper than Mesa will sell it to you for.
[23:30:37] <JT-Shop> andypugh: cool video
[23:30:50] <SWPadnos> you need 6 outputs for 3 motors (step/dir and 2x PWM/dir), you need 4 inputs for the two encoders
[23:31:14] <andypugh> But you might well learn a lot about motion control building your own p-port system.
[23:31:25] <SWPadnos> that can be done, but it doesn't leave much room for additional inputs (like limit switches) or outputs (like motor enable)
[23:31:25] <AR_> http://www.ni.com/devzone/advisors/motion/buehler.htm
[23:31:40] <JT-Shop> only way I'd try and build something like that is if I didn't care if it worked and only wanted the education from building it
[23:31:51] <SWPadnos> actually, you'll learn a lot about making a cheap H-bridge, and a little about motion control :)
[23:31:55] <SWPadnos> have fun. bbl
[23:32:08] <AR_> well, Im building a cheap 3 axis cnc
[23:32:10] <JT-Shop> I'll stick to Mesa
[23:32:21] <JT-Shop> and Gecko
[23:32:26] <AR_> i bought some used assemblies on ebay and these motors came with it
[23:32:37] <AR_> i was just wondering if they may be useable for something
[23:32:46] <SWPadnos> certainly can be :)
[23:32:48] <SWPadnos> bye
[23:32:58] <andypugh> Servos are better than steppers
[23:33:36] <PCW_> PCW_ is now known as PCW
[23:34:19] <andypugh> Do you have any steppers, or are these the only motors you have now?
[23:34:35] <AR_> i have steppers
[23:34:39] <andypugh> And are they already fitted to the actuators?
[23:34:51] <AR_> no
[23:34:58] <andypugh> Ah, OK
[23:35:35] <andypugh> Motor already on actuators, and no steppers in the cupboard would be a no-brainer on all levels.
[23:35:43] <AR_> lol
[23:35:48] <andypugh> Do you have drivers for yiour steppers?
[23:36:10] <AR_> yeah
[23:36:57] <andypugh> What torque?
[23:37:09] <AR_> these motors came with gearheads on them for a timing belt, and one of the leadscrews had a gear on the end too and a belt
[23:37:26] <AR_> andypugh, i dont know
[23:37:30] <andypugh> The DC motors are not stellar performers on the torque front (0.35Nm)
[23:37:40] <AR_> http://www.ni.com/devzone/advisors/motion/buehler.htm
[23:37:52] <AR_> i think these specs at the bottom match these motors
[23:38:17] <andypugh> Aye, that is where I get the 0.35Nm from
[23:38:24] <AR_> yeah lol
[23:38:56] <andypugh> What do you know about your steppers? (frame size, current?)
[23:39:22] <AR_> nema 23
[23:39:27] <AR_> i run them with 27v
[23:39:42] <AR_> 2A
[23:39:47] <AR_> 1.8ohm
[23:40:12] <andypugh> I would guess at about 1.5Nm from them
[23:40:58] <andypugh> But that is at 0rpm, steppers fade away very fast with speed
[23:41:15] <AR_> yeah
[23:42:16] <andypugh> However, I don't _think_ that the DC motors you have will outperform the steppers yiou have
[23:42:55] <andypugh> But I am just some guy you have never met on the internet, do your own research
[23:43:26] <andypugh> Do you have a stepper driver?
[23:47:59] <JT-Shop> there is quite a bit of info on steppers on the EMC wiki site