#emc-devel | Logs for 2008-07-31

[08:29:55] <Preben> Preben is now known as pmbdk
[11:14:36] <pmbdk123> pmbdk123 is now known as pmbdk
[12:12:54] <pmbdk123> pmbdk123 is now known as pmbdk
[14:21:44] <jepler> hm, what problem would arise if stepconf didn't ask for direction setup & hold, and just made them very big numbers (like 200us) instead?
[14:26:15] <cradek> probably none
[14:27:00] <skunkworks_> someone would notice on a direction change there is a 'large delay' ;)
[14:28:57] <jepler> skunkworks_: heh
[14:29:45] <cradek> the axis is always stopped at direction changes anyway - it probably doesn't make any difference
[14:30:25] <skunkworks_> I remember playing with the numbers and wonering why the max frequency wasn't changing.. then I had a duh moment.
[14:33:56] <CIA-35> EMC: 03jepler 07TRUNK * 10emc2/src/emc/usr_intf/stepconf/stepconf.glade: increase the range of step timing values accepted
[14:36:02] <CIA-35> EMC: 03jepler 07v2_2_branch * 10emc2/src/emc/usr_intf/stepconf/stepconf.glade: from TRUNK: increase the range of step timing values accepted
[14:50:18] <SWPadnos> other axes aren't necessarily stopped though
[14:50:40] <SWPadnos> so you can screw up something like an arc
[15:08:58] <jepler> hm -- check my math. on a 10" circle cut at 1inch/second, not moving for 200us after a reversal would represent a deflection of sin(2*pi*200e-6/10) = .00013 inches
[15:12:34] <SWPadnos> err - I can't check math at the moment. lack of caffeine, you see :)
[15:18:14] <SWPadnos> actually, with that driver it wouldn't be an issue at all - the 5KHz max step rate means that there could only be one microstep "extra" in that time
[15:18:22] <SWPadnos> at most one
[15:24:49] <steves_logging> steves_logging is now known as steve_stallings
[15:25:00] <SWPadnos> hi Steve
[15:25:26] <steve_stallings> By removing the setup time you risk confusing the more knowledgeable users who would want to confirm that they were not violating that sped.
[15:25:28] <steve_stallings> spec
[15:25:50] <steve_stallings> Hi SWP, how was the trip, did the eee work out?
[15:26:09] <SWPadnos> trip was great - I didn't end up bringing the eee
[15:26:18] <steve_stallings> duh
[15:26:45] <SWPadnos> oh right - we needed space for photos or something, which made it not quite functional
[15:27:20] <SWPadnos> I did the updates on the Ubuntu disk, but of course couldn't find a way of making it boot from that automatically
[15:27:34] <SWPadnos> and I didn't have the time to figure out how to get the eee OS into "advanced mode"
[15:27:46] <SWPadnos> thanks though, it was interesting to make the attempt ;)
[15:28:09] <steve_stallings> not a problem, just having wifi on the r
[15:28:27] <steve_stallings> ubuntu is a gteat improvement
[15:28:53] <SWPadnos> if I had more time, I probably would have made it work
[15:29:02] <steve_stallings> dang, put the food down, use two hands, then I might be able to type
[15:29:12] <SWPadnos> hmmm - there's an idea
[15:34:53] <cradek> hi steve!
[15:35:50] <steve_stallings> gee, its been about a week, I should run hide....
[15:36:00] <cradek> ha
[15:36:04] <cradek> any progress?
[15:36:06] <steve_stallings> on the other hand, you seem busy with the Hardinge
[15:36:27] <steve_stallings> nope, went to see the folks and made a long weekend of it
[15:36:31] <cradek> yeah the mill is currently pretty useful - the lathe, not so much
[15:36:36] <jepler> SWPadnos: I don't use advanced mode on my eee, just the ctrl-alt-t terminal shortcut and the ctrl-alt-n firefox shortcut
[15:36:43] <SWPadnos> heh
[15:37:32] <SWPadnos> I probably could have gotten by with it (almost assuredly, since the hotels charged 27 euro/day for internet access)
[15:37:44] <SWPadnos> which means I didn't use it much
[15:37:59] <steve_stallings> have you figured out if the GE 550 is actually runnable?
[15:38:42] <cradek> it might have a problem with the tape reader, but everything seems to work at MDI
[15:38:49] <cradek> so I bet I could get it going pretty easily.
[15:39:04] <steve_stallings> I figure that fixing old servo drives may be worth the trouble, but if the 550 is broken that is a much harder road to travel
[15:39:27] <cradek> steve_stallings: I do hope to keep the velocity mode drives
[15:39:44] <cradek> there's a problem with Z oscillating that I haven't quite nailed
[15:40:41] <cradek> I might get to work on it more tonight.
[15:41:28] <SWPadnos> sigh. I wish my bridgeport weren't turning into a heap of rust
[15:41:36] <steve_stallings> saw that, my first guess would lost motion in the feedback loop, second guess would be dried up cap in a low pass filter in the tach feedback path
[15:42:06] <SWPadnos> the weather has been the absolute worst for rust - rain every day, followed by heat (80s-90s)
[15:42:26] <SWPadnos> then cool nights, so it can get the maximum condensation when it gets humid the next day
[15:42:33] <steve_stallings> assuming the osc is in the greater than 20 Hz region, if slower then it might be mis-adjustment
[15:43:14] <cradek> the osc was about 65Hz. I fixed the loose motor pulley and now it's much faster.
[15:43:40] <steve_stallings> Cradek - do you know the control bandwidth, Jon Elson said the old AB he had was only 25 Hz
[15:43:48] <cradek> (I think it's mechanical.)
[15:43:59] <cradek> no, I don't know that
[15:44:48] <steve_stallings> does the osc continue if the command input to the amp is removed?
[15:45:15] <cradek> it did, but I have not tested that with the pulley fixed yet.
[15:45:29] <steve_stallings> i.e. does the osc feedback path include the control, or just the tach and amp
[15:45:32] <cradek> so now, so far, I don't know which loop is oscillationg
[15:45:51] <cradek> right, that's the first thing I will find out when I get going again
[15:46:05] <cradek> I broke a coupling and had to order replacements.
[15:46:10] <cradek> hope to get them today
[15:46:31] <steve_stallings> what, no rubber hose and clamps?
[15:46:42] <cradek> it was very tempting
[15:46:51] <cradek> I looked around and didn't find hose the right size :-)
[15:51:46] <SWPadnos> hey Steve - could you email me your shipping address so I can get the eee back to you before the next CNC workshop :)
[15:57:16] <steve_stallings> done
[15:57:25] <SWPadnos> okie dokie - thanks again
[15:57:45] <SWPadnos> phone number?
[15:57:54] <SWPadnos> I'll probably UPS it
[15:58:36] <SWPadnos> wow - NewEgg's "shell Shocker" is a pretty good deal - 8GB USB memory stick for $18.99 including shipping
[16:00:33] <skunkworks_> wow - I just got some from buy.com for 23 iirc free shipping - that is better yet
[16:01:45] <skunkworks_> sandisk
[16:02:27] <SWPadnos> sandisk is likely better than Transcend or TotalMegaStuff or whatever it was :)
[16:02:43] <SWPadnos> ah -Super Talnet
[16:02:48] <SWPadnos> Talent even
[16:02:58] <SWPadnos> they're nmot bad, but not exactly top notch either
[16:02:59] <skunkworks_> I had to remove teh u3 from it.
[16:03:05] <SWPadnos> yeah, me too
[16:03:09] <SWPadnos> on a couple of others
[16:03:27] <SWPadnos> the interesting thing is that the U3 removal utility has a nice little bug
[16:03:56] <SWPadnos> when it's backing up the data from the other partition, if you hit "cancel", then it cance;s the backup, but doesn't cancel the formatting of the drive
[16:05:57] <jepler> * jepler wonders what the performance is like if you attach 4 of them to a USB hub and RAID-0 them -- it might give increased read performance if this old benchmark is accurate http://arstechnica.com/reviews/hardware/flash.ars/8
[16:06:09] <jepler> of course, I don't wonder enough to spend over a hundred bucks on it :-P
[16:06:50] <SWPadnos> the drives are listed as 120X (18MB/sec), so you could certainly fit a few of those into the 60MB/sec of USB2
[16:07:20] <SWPadnos> 4 is probably the right number for making it USB limited rather than drive limited
[16:09:22] <jepler> I just picked 4 since that's a typical number of ports on a USB hub
[16:09:40] <SWPadnos> I think it also happens to be the "right" number :)
[17:00:13] <skunkworks_> hmm - I don't know if I can fit all this on the board.
[17:00:48] <skunkworks_> My other thought is that I would have the driver board - and the logic board that would plug one on top the other.
[17:01:38] <skunkworks_> the driver board would have the fets and driver ic (plus the current sense resister) and the rest would be on the other board
[17:30:44] <steve_stallings> steve_stallings is now known as steves_logging
[19:47:34] <skunkworks_> eagle is pretty cool...