#emc-devel | Logs for 2007-08-14

[00:16:57] <jmkasunich_> jmkasunich_ is now known as jmkasunich
[00:20:07] <jmkasunich> hi guys
[00:20:17] <jmkasunich> sounds like fun in Lincoln
[00:32:28] <skunkworks> yah - hope someone is videotaping ;)
[00:35:22] <jepler> * jepler is glad he's not involved in this
[00:35:35] <jepler> I just want to see it make chips once cradek is done retrofitting it with emc later this evening
[00:35:36] <jmkasunich> he didn't recruit you?
[00:35:39] <jepler> nope
[00:35:40] <jmkasunich> lol
[00:35:47] <jmkasunich> later this evening ;-)
[00:35:48] <skunkworks> really - I love stuff like that.
[00:36:17] <jmkasunich> same here
[00:36:33] <jmkasunich> although to be honest, when moving a machine I prefer not to have any help
[00:36:49] <skunkworks> when we placed the kerney trecker - we used a couple 20 ton jacks and lots of 4X4s
[00:36:54] <jmkasunich> if you have help, you're tempted to rush things, so people don't get tired of standing around
[00:37:03] <skunkworks> yah
[00:39:33] <jepler> jmkasunich: I have a question that I bet you can answer. If you're doing a digital AC lamp dimmer, why do it by "phase angle control" instead of turning on or off for an entire 180 degrees of the sine wave?
[00:39:52] <jmkasunich> if you drop entire half cycles, you are more likely to get flicker
[00:40:13] <jmkasunich> and you really should drop whole cycles, to avoid a net DC component that transformers and such won't like
[00:40:55] <jmkasunich> phase control also has a much smoother range of levels
[00:41:07] <jmkasunich> you can vary the phase angle by very small amounts, but you can only drop integral cycles
[00:41:35] <jmkasunich> 120 half-cycles per second, for 8 bit resolution you'd have a 2 second period :-(
[00:41:48] <jepler> that all makes sense, thanks
[00:42:11] <jepler> so I guess we just need 600Hz AC instead of 60Hz
[00:42:19] <jmkasunich> heh
[00:42:34] <jmkasunich> cycle dropping is used industrially (and maybe elsewhere) for heaters and furnaces
[00:42:50] <jmkasunich> where thermal inertia filters out the 2 second or whatever effects
[00:43:11] <jmkasunich> but for lighting, you can see flicker iup to 50Hz or more
[00:45:11] <jepler> for phase angle it seems like the relationship between power & angle must be very nonlinear
[00:45:45] <jmkasunich> it is somewhat
[00:46:08] <jmkasunich> the relationship between power and light output is probably even more nonlinear
[00:46:28] <jepler> mumble black body, or some other reason?
[00:47:01] <jmkasunich> first question is what kind of light ;-)
[00:47:03] <jepler> the color of a dimmed household lamp sure is different
[00:47:08] <jmkasunich> incandescent?
[00:47:09] <jepler> yeah
[00:47:37] <jmkasunich> yeah, light vs temperature is non-linear, due to blackbody stuff
[00:47:59] <jmkasunich> temperature vs power is nonlinear - I think radiated heat transfer is something like temperature ^ 4
[00:48:19] <jmkasunich> power vs voltage is nonlinear because the filament resistance changes with temperature
[00:48:33] <jmkasunich> if you have a dimmable light, you can see the latter effect as hystersis
[00:48:45] <jepler> and human perception is nonlinear too
[00:48:52] <jmkasunich> turn it down slowly, mark a setting on the dial where it is very dim, but visible
[00:49:08] <jmkasunich> then turn it down to off, and slowly turn up to the same setting
[00:49:30] <jmkasunich> you might find that the brightness at the same setting is significantly different
[00:54:38] <jmkasunich> heh, the dark sky locater at http://www.darksky.org/darksky/index.php has a minor bug
[00:54:50] <jmkasunich> I guess its technically not a bit
[00:54:51] <jmkasunich> but
[00:55:04] <jmkasunich> it suggests that I'll find dark skyes in the middle of lake erie
[00:55:16] <jmkasunich> s/bit/bug
[00:55:23] <jmkasunich> can't type for crap
[12:29:27] <skunkworks> cradek: how did it go?
[12:32:11] <jepler> skunkworks: take a look on nsa maps and see whether it's still in his driveway or whether he got it inside
[12:37:29] <skunkworks> hmm. :)
[12:37:48] <skunkworks> jepler: morning
[12:49:18] <jepler> hi sam
[12:50:07] <skunkworks> How is the stepgenerator coming? still going to fit?
[12:52:05] <jepler> hopefully
[12:52:35] <jepler> I have a few more things to finish up before I check in the new changes
[12:53:13] <jepler> and one of those things I will probably need to test on a real stepper
[12:54:15] <skunkworks> how did you end up doing about the low speed issue?
[12:54:19] <jepler> well that's the thing I need to test
[12:55:00] <jepler> you will get a choice of 300kHz or 75kHz max speed; the 75kHz max speed has speed increments that are much finer, and hopefully that makes the sound of irregularity go away
[12:55:38] <skunkworks> ok - that is what you had mentioned before. cool
[12:56:23] <jepler> I dunno if the effect will be large enough -- the increments will only be 4x finer, which might not be enough to make a big difference
[12:57:22] <jepler> I also noticed that under at least some circumstances the position settles more than 1 full step away from the desired position, I need to figure out why that is and do something about it
[12:58:46] <jepler> hi steve_stallings
[12:59:08] <steve_stallings> hi Jef
[12:59:13] <steve_stallings> duh, Jeff
[13:00:38] <steve_stallings> so is Chris still in one piece after his encounter with the Bridgeport?
[13:01:14] <jepler> we haven't heard
[13:01:32] <jepler> seems to be the question on everybody's mind though
[13:01:43] <skunkworks> he had the forklift until 8 - I assume he is taking the morning off :)
[13:01:54] <skunkworks> am
[13:02:04] <jepler> yeah he was going to take today off
[13:02:15] <skunkworks> nice - new toy - I would too :)
[13:02:41] <skunkworks> I wonder how he is going to do the whole 3 phase thing...
[13:02:48] <steve_stallings> but like most new babies, it wants a lot of attention..
[13:03:12] <steve_stallings> right now his problem is getting some of the top end off go it will go through the door
[13:03:25] <jepler> skunkworks: at one point he said the seller had a 1ph to 3ph converter that would go with it for a few extra bucks
[13:03:50] <skunkworks> lots of people use them.
[13:04:23] <skunkworks> I would probably just wire it single phase and get a vfd for the spindle.
[13:04:53] <skunkworks> but that is more money ;)
[13:06:21] <jepler> steve_stallings: does the machine start with a manual spindle speed control, or what?
[13:09:28] <steve_stallings> varispeed via mechanical Reeves drive
[13:10:17] <skunkworks> does the cnc control the pully?
[13:10:24] <steve_stallings> spindle start via a front panel switch, Bridgeport's idea of a safety feature
[13:10:29] <skunkworks> ha
[13:10:49] <skunkworks> so - totally manual spindle?
[13:11:27] <steve_stallings> There is an air motor to run the speed up and down, but it just responds to buttons on the control panel
[13:12:15] <steve_stallings> no direct control from S words
[13:12:40] <steve_stallings> not really a big issues since tool change is manual too
[13:13:11] <skunkworks> yah - I suppose. I see cradek calling in sick for the next week or so.. :)
[13:13:58] <skunkworks> steve_stallings: what are your views on the micro-mill/x1?
[13:14:25] <steve_stallings> X1 is a good converson candidate, X2 less so despite being heavier
[13:15:14] <steve_stallings> X2 does have R8, which make tools easier to find, but also encourages unrealistic expectations of capability
[13:15:39] <skunkworks> - that was the main thing I didn't like about the x1 - (morise taper)
[13:15:47] <skunkworks> moris?
[13:15:52] <skunkworks> whatever
[13:15:53] <steve_stallings> morse
[13:16:00] <skunkworks> there you go
[13:16:24] <skunkworks> the x2 doesn't have a z axis leadscrew does it?
[13:16:40] <steve_stallings> I think Taig has the right idea with their direce ER collet spindle
[13:17:30] <steve_stallings> X2 has rack drive in Z but plenty of room to add a ball screw, you just have to figure out brackets
[13:17:40] <skunkworks> ah
[13:18:14] <steve_stallings> if you modify the head mounting block, the Z ball screw will fit directly in front of the column (where it can collect chips)
[13:19:01] <skunkworks> like how jone has his setup?
[13:19:05] <steve_stallings> despite the chip problem, this is the location that works best because of cantilevered weight of head
[13:19:49] <steve_stallings> Gosh, I forget where Jon put his, I only paid attention the his electronics 8-(
[13:20:01] <skunkworks> :) it is right out in from iirc
[13:20:53] <skunkworks> I managed to get one of these http://www.electronicsam.com/images/engraver/engraver.JPG
[13:21:32] <skunkworks> cheap - so I am planning on selling it and taking a small amount of the money and buy a small mill
[13:21:38] <steve_stallings> OK, the X2 head mount is stacked blocks that come apart easily, and you have to mill a notch in 2 or 3 cast iron webs on the back side of the head mount block, easy if you have access to a Bridgeport
[13:22:53] <skunkworks> I have access to a machine shop.
[13:23:44] <skunkworks> steve_stallings: http://www.youtube.com/watch?v=dKz81fY1OjY :)
[13:23:45] <steve_stallings> The X2 really needs a ballscrew on the Z due to weight of head, the X1 can get by with the stock Acme screw
[13:24:14] <skunkworks> you where talking to my dad about being able to split the z casting to adjust the nut?
[13:24:20] <skunkworks> on the x1
[13:24:30] <steve_stallings> X1 has adjustable split nuts on X and Y, plus you can make the Z adjustable by slitting the block and adding a setscrew
[13:24:49] <steve_stallings> Just be careful, it is cast iron and excess force will crack it
[13:25:53] <skunkworks> Cool - thank you
[13:27:00] <steve_stallings> X2 nuts on X and Y are not adjustable. It is possible to split them, but not easy, plus they are difficult to access for adjustment.
[13:27:30] <skunkworks> hmm - sounds like the x2 has issues. :)
[13:27:49] <steve_stallings> Overall the screws on the X1 and X2 are among the better finished parts of these machines.
[13:29:39] <steve_stallings> X2 will take heavier cuts and offers more potential for upgraded tool change, like Tormach system, but I think the X1 is a better balance of size, power, features.
[13:30:05] <skunkworks> have you done a lot of machining with your x1?
[13:30:26] <skunkworks> do you use a drill chuck most of the time?
[13:30:32] <steve_stallings> Plus there are upgrades for X and Y travel available for the X1 from Little Machine Shop if you get rich later
[13:30:49] <skunkworks> heh
[13:31:38] <steve_stallings> I do very little actual cutting, but my friend Tex does a fair bit with his. He is the one who actually did the mechanical work on mine. He also did all the gear cutting stuff I was showing.
[13:32:03] <skunkworks> neat.
[14:05:29] <jepler> it's too bad skunkworks wants a fair price for that engraver or I'd try to buy it off him
[14:06:43] <skunkworks> if it wasn't for the garage right now.. (concrete work is expensive when you don't do it yourself) I might be enclined. but as it is now I am going to put it on ebay once I get the controller fixed.
[14:07:15] <skunkworks> cool little machine - all cast aluminum.
[14:09:27] <skunkworks> heh http://cgi.ebay.com/New-Hermes-V7200-rotary-engraver-W-EP-Module_W0QQitemZ320147485133QQihZ011QQcategoryZ46744QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
[14:43:45] <cradek> the mill is IN the garage
[14:43:58] <jepler> yay!
[14:44:02] <cradek> only the expected very minor injuries were sustained
[14:44:31] <cradek> now the garage is cooling while I shower
[14:44:39] <cradek> next step: make it the original height again
[14:45:53] <alex_joni> yay
[14:45:54] <alex_joni> bbl
[14:47:14] <cradek> bbl
[14:51:16] <skunkworks> COol
[15:22:17] <steve_stallings> What, Cradek didn't notch the doorway header after all?
[15:29:38] <cradek> nope
[15:29:44] <skunkworks> he probably thought about raising the garage..
[15:29:44] <cradek> saner heads prevailed
[15:29:48] <skunkworks> oh - there he is ;)
[15:30:12] <cradek> once I was surprised by how heavy a part was, but it was already off, but still attached by an oil line...
[15:30:19] <cradek> that was my only big adventure really
[15:30:59] <cradek> so, hold it with one hand, go down the ladder to get two wrenches for the oil fitting, use my other two hands to unhook the oil line, carry it down the ladder.
[15:32:24] <skunkworks> anyone taking pictures?
[15:32:30] <cradek> sadly no
[15:32:34] <skunkworks> aww
[15:32:36] <cradek> the ramp setup was pretty fun, should have taken some
[15:33:05] <cradek> the tree's only instruction was to hold still, and it did a great job
[15:33:43] <skunkworks> mostly trees are good at that.. Sometimes they are spitefull though - you need to be careful. ;)
[17:59:42] <steve_stallings> steve_stallings is now known as steves_logging
[19:00:18] <skunkworks> cradek: I think it is time for a update. ;)
[19:36:38] <alex_joni> skunkworks: what kind?
[19:37:29] <skunkworks> his mill assembly project
[19:40:43] <skunkworks> cradek is now a millwrited
[19:40:48] <skunkworks> oops millwrite
[19:43:02] <alex_joni> ah
[19:44:08] <alex_joni> darn.. ordered another 20" widescreen.. and they ran out of 20"-es, so I had to get a 22" one
[19:46:04] <skunkworks> darn ;)
[19:46:56] <alex_joni> yeah, I'll be getting it tomorrow it seems
[19:47:10] <alex_joni> hopefully it won't fit on my dad's desk :D
[19:47:26] <skunkworks> heh
[21:27:00] <alex_joni> * alex_joni is off to bed
[21:28:06] <skunkworks> Night alex
[23:05:38] <skunkworks> logger_dev: bookmark
[23:05:39] <skunkworks> Just this once .. here's the log: http://www.linuxcnc.org/irc/irc.freenode.net:6667/emcdevel/2007-08-14.txt
[23:37:59] <Guest482> Guest482 is now known as skunkworks_