#emc | Logs for 2008-07-16

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[03:06:49] <tomp2> just a fun link, an old timey carbide lamp for a bicycle http://www.jkdey.com/cycle.htm.
[03:32:32] <Guest488> Adding an encoder to my lathe for threading what count resolution should I look for, running a 3k spindle and elson's servo board?
[03:36:42] <jmkasunich> if you are counting pulses in hardware, you can use just about anything
[03:36:57] <jmkasunich> if in software, you need to watch out for the high frequency limit
[03:37:20] <jmkasunich> speed in RPM / 60 = speed in revs/sec * counts/rev = frequency in counts per sec
[03:37:31] <jmkasunich> software can't count much over 20,000 counts/sec
[03:37:36] <jmkasunich> hardware can count at least 10x that
[03:39:19] <Guest488> thanks
[03:42:58] <Guest488> is there a sweat spot on rev count?
[03:43:25] <jmkasunich> not sure what you mean
[03:43:41] <jmkasunich> for threading, "a few hundred" counts/rev should be fine
[03:44:07] <jmkasunich> encoders are available from "a few dozen" counts per rev, to "a few thousand"
[03:44:13] <jmkasunich> the highest end of the scale usually costs more
[03:44:28] <jmkasunich> but up to about 1000 cpr is pretty much the same
[03:44:35] <cradek> we rigid tap on the mazak with a 360 line encoder
[03:44:44] <jmkasunich> if you are buying new, look at usdigital for what is availalbe
[03:45:00] <cradek> for that it is plenty. and threading is much more forgiving than rigid tapping
[03:45:08] <jmkasunich> if you are buying ebay or scrounging, just see what is available, then do the math to make sure the frequency isn;t too high
[03:46:58] <Guest488> do I need an index pulse for threading?
[03:47:03] <jmkasunich> yes
[03:47:03] <cradek> yes
[03:47:12] <jmkasunich> hey, there's an echo in here
[03:47:29] <cradek> only on the easy questions
[03:47:45] <jmkasunich> yeah
[03:47:53] <cradek> goodnight folks
[03:47:54] <jmkasunich> this half of the echo is going to sleep
[03:47:58] <cradek> ha
[03:47:59] <jmkasunich> goodnight
[03:48:02] <jmkasunich> (echo again)
[03:50:59] <chr0n1c> any ideas on where to source a dual gang 33k potentiometer?
[03:51:12] <chr0n1c> i've been googling..
[09:47:42] <micges> hi all
[10:49:59] <alex_joni> hi micges
[11:47:08] <cradek_> cradek_ is now known as cradek
[13:25:43] <alex_joni> bbl
[14:49:17] <skunkworks_> wow... just wow.. http://www.cnc.info.pl/topics60/frezarka-cnc-x1500-y500-z500-vt1706.htm
[14:54:25] <archivist> hmm pics are good and I like the gears
[14:54:42] <archivist> cant understand da werds
[14:56:42] <archivist> I also like making bits bigger than the machines are designed for
[14:58:56] <skunkworks_> what is the gearbox for?
[14:59:08] <skunkworks_> I wonder
[15:00:45] <archivist> ratio will vary with angle, sort of trick shapers use (they use cams)
[15:01:18] <skunkworks_> ah
[15:03:47] <archivist> must be interesting making the internal gear, can only easily be made by generation or some evil wire erosion
[15:04:30] <skunkworks_> we have a planer almost that big..
[15:04:44] <skunkworks_> granted - it isn't together right now.
[15:05:38] <skunkworks_> that machine is made similar to our kerney and trecker.. all weldments. (1 inch thick weldments though)
[15:10:38] <skunkworks_> I don't understand why people like to use 'love-joy
[15:11:05] <skunkworks_> style couplers for connecting servos/stepper to leadscres.
[15:11:11] <skunkworks_> leadscres
[15:11:13] <skunkworks_> jeezew
[15:11:18] <skunkworks_> leadscrews
[15:12:07] <skunkworks_> and the missing 'w' shows up in jeeze
[15:22:02] <fenn> sweet. they forgot to show the step where you fill it all with epoxy-granite
[15:23:57] <archivist> or its hollow and sings
[15:24:01] <fenn> also notice the foundry flasks in the background
[15:24:26] <fenn> i wonder if they annealed the whole thing once it was welded
[15:26:09] <archivist> the two wooden packing cases?
[15:29:25] <skunkworks_> I think it should be filled with a non-newton liquid... Like silly pudy.
[15:34:39] <skunkworks_> http://www.cnczone.com/forums/showthread.php?p=477086#post477086
[15:41:07] <fenn> in front of the brown garage doors.. i suppose they might be shipping crates but they have little nubs sticking off the side like you'd use for alignment
[15:41:41] <fenn> skunkworks_: the magic technobabble words you're looking for are "viscoelastic shear damping"
[15:42:59] <skunkworks_> fenn: thanks.. I didn't know the technical term :)
[15:49:16] <skunkworks_> fenn: http://www.electronicsam.com/images/KandT/servostart/newschem2.png
[15:49:36] <skunkworks_> yes - there is actually an drive enable... :)
[15:50:08] <skunkworks_> maybe that should be "drive enable" as this is not tested yet.
[15:50:22] <skunkworks_> and "current limit" ;)
[15:52:14] <fenn> current limit is more fun to test :P
[15:54:42] <skunkworks_> heh - jmkasunich says I should use a real comparator instead of an op-amp.. So there are a few changes yet.
[15:55:29] <skunkworks_> but the logic works out that I can put 2 amps on 1 board and use up all the extra gates.
[15:57:05] <fenn> why bother.. comparator is like fifty cents
[15:57:46] <fenn> having a separate board for each axis is worth way more in terms of troubleshooting time
[15:59:30] <skunkworks_> I feel bad for the unused gates..
[16:01:08] <fenn> poor poor gates, he must be so bored now that he has no job
[16:02:16] <fenn> there's some video of that welded mill.. it does screech: http://pl.youtube.com/watch?v=JyHQG7bvp68
[16:05:01] <fenn> looks like it has through-tool coolant too
[16:06:31] <skunkworks_> yes - he has a picture of coolant spraying out of the end of a drill
[16:13:24] <fenn> ok that's enough polish tv for now.. :)~
[16:22:55] <Guest739> Is anybody can help to build embedded-like version of emc2 ? Ubuntu is bad decision
[16:26:43] <Roguish> hey all, who's sells an inexpensive (and reliable) parallel port breakout w/ opto-isolator? and how much $$ ??
[16:55:05] <LawrenceG> Roguish, I made this ... http://members.shaw.ca/swstuff/bob.html it is buffered, but only has a couple of inputs opto'd, I use it to drive Parker stepper drives which jave there own optos on step/dir
[16:55:30] <skunkworks_> BigJohnT: good answer. :)
[16:55:45] <BigJohnT> LOL your fast or at lunch :)
[16:56:04] <skunkworks_> just got back from a lunch walk :)
[16:56:15] <LawrenceG> Hi John... just out of bed here....
[16:56:25] <BigJohnT> Hi Lawrence
[16:56:50] <lewin1> lewin1 is now known as lewing
[16:58:01] <LawrenceG> hi skunkworks ... off to raid the coffee pot
[16:58:06] <BigJohnT> wow AB push buttons LawrenceG
[16:58:07] <Roguish> LawrenceG: thanks. i'm looking to add some i/o to an M5i20 system. kinda using up the 32 i/o pretty fast interfacing to an existing panel.
[16:58:23] <Dallu1> Guest739: if you are looking to build an embedded version of Linux to run EMC, you probably want to check out Gentoo or t2, might take you a month or two though
[16:58:49] <Dallu1> bahh didn't notice he had left :P
[16:58:54] <BigJohnT> tomp: are you around?
[16:58:54] <LawrenceG> BigJohnT, only the best!
[16:59:43] <BigJohnT> only takes about 5 of them to cost more than a 6" touch screen!
[17:01:05] <LawrenceG> no kidding.... I raided the junkbox.... I had been hoarding these for the last 20 years from an industrial panel I took apart
[17:02:26] <BigJohnT> we bought a couple of panels from a junk guy that had about 40 on each one. We paid $10 each... We don't use them for customers but for shop projects they are great
[17:06:18] <BigJohnT> LawrenceG: I wish you had a CNC plasma cutter
[17:07:00] <LawrenceG> me too!
[17:08:43] <BigJohnT> then you could design a THC and I could copy it :)
[17:10:45] <LawrenceG> back from kernel update
[17:19:48] <BigJohnT> LawrenceG: if you had a plasma cutter you could design a THC and I could test it for us :)
[20:04:56] <Hugomatic> Hello guys,
[20:06:23] <Hugomatic> I am looking for a unipolar stepper motor driver for a Sherline mill (4 axis). Any good pointers? The Sherline box is way too expensive (700$) and I can solder. thanks
[20:06:52] <Hugomatic> The EMC FAQ suggests Linistepper, but no one has tried it
[20:09:18] <Hugomatic> Is there a pluto based stepper driver?
[20:12:43] <skunkworks_> what you need is the drive.. (what runs the stepper) the pluto can be setup to output step and direction.. but you still need the drive.
[20:14:04] <skunkworks_> have you looked at cnczone? I think there are a lot of people using the linistepper.. I have no experience with them.
[20:14:15] <Hugomatic> skunkworks: sorry I am not sure I understand. I need something between my parallel port and the motors... pluto is not the way?
[20:15:23] <skunkworks_> No - in that respect - printer port -> pluto -> drives -> stepping motors.
[20:15:54] <fenn> you dont want a unipolar stepper driver
[20:15:56] <Hugomatic> skunkworks: I will check ´╗┐cnczone as well. So what is it that the pluto does?
[20:16:02] <fenn> i suggest waiting until the new cheap-o gecko drives come out
[20:16:23] <skunkworks_> depending on how fast you need. - you could probably just do - printer port -> Break out board -> drives -> stepping motors.
[20:16:24] <fenn> linistepper is mainly for telescope mounts
[20:16:37] <Hugomatic> fenn: thanks for the info
[20:17:14] <skunkworks_> it really depends on the stepping motors you have... You might be able to run them bi-polar..
[20:17:59] <fenn> you can connect drives to the parport directly but this is potentially a bad idea due to electrical shorts and noise. a board that goes between the parport and drives and other stuff is called a breakout board
[20:18:41] <fenn> i can't recommend any as i haven't really studied the market
[20:19:15] <Hugomatic> fenn, skunkworks: Its for a friend's old Sherline Mill. I already put din5 connectors so I can use it with my Sherline box, so I think my motors are unipolar
[20:20:14] <tomp> bbl
[20:20:15] <Hugomatic> Thanks for the info guys...
[20:20:53] <skunkworks_> Hugomatic: this is a good primer.. http://www.geckodrive.com/photos/Step_motor_basics.pdf
[20:21:53] <Hugomatic> Those gecko boxes are not very expensive.... :)
[20:26:54] <Dallur> Hugomatic: you can also check http://www.xylotex.com/
[20:28:43] <Hugomatic> Dallur: nice link, thanks...
[20:31:15] <Hugomatic> Dallur: I think my motors are unipolar, so a xylotex board might not work
[20:49:46] <Dallur> Hugomatic: There are also several others plus it's quite doable to build one if you have way to much time on your hands :)
[20:54:57] <alex_joni> are you sure they are Unipolar?
[20:55:06] <alex_joni> I got some steppers from sherline, and they were bipolar
[21:29:05] <alex_joni> good night all
[21:37:36] <pjm_> gn
[22:25:26] <dmess> hi all
[22:39:10] <chr0n1c> dmess!
[23:04:48] <dmess> just cropped a COOL guitar..... cant wait till it gets here.. Martin Backpacker ... ;)
[23:06:17] <dmess> still lookin for servo/stepper drivers
[23:08:35] <chr0n1c> buy something simple to start...
[23:08:43] <chr0n1c> buy/build*
[23:08:58] <chr0n1c> then if you need it add a bigger driver someday
[23:52:37] <cradek> jepler: I'm not using that spindle and probably won't for a while. it takes a few weeks to get one from the guy. if you order a replacement for me, you can just have it.