#emc | Logs for 2008-07-15

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[00:37:15] <[1]a-l-p-h-a> [1]a-l-p-h-a is now known as a-l-p-h-a
[01:45:20] <dmess> hey Alpha... you home??
[03:09:48] <tcninja12> hello
[03:13:32] <SWPadnos_> SWPadnos_ is now known as SWPadnos
[03:45:41] <chr0n1c> .join #electronics
[03:45:49] <chr0n1c> ha!
[04:23:23] <[1]a-l-p-h-a> [1]a-l-p-h-a is now known as a-l-p-h-a
[06:38:44] <micges> hi all
[11:27:33] <Phreedom_> Phreedom_ is now known as Phreedom
[13:46:11] <cradek> haha, organic's mail is funny
[13:47:53] <archivist> crash method :)
[14:01:04] <skunkworks_> Good morning :)
[14:03:32] <rayh> How you doing today, skunkworks?
[14:05:07] <skunkworks_> it is my monday... so not bad
[14:06:11] <skunkworks_> going to be hot today.. first 90 degree day here I think.
[14:09:05] <rayh> We had a storm overnight but it looks like a warm one here also.
[16:00:28] <Strogg> ahoy there
[16:01:29] <Strogg> I've been pondering the idea of doing CNC for creating PCBs, but I don't have a mill.. are there any plans/schematics out there for building one that compatible with emc?
[16:03:10] <cradek> pretty much every 3 axis mill design would be compatible with emc
[16:03:29] <cradek> for creating PCBs you need very low backlash in the axes and a very fast spindle for engraving tools
[16:04:11] <cradek> also you need very good table flatness because you are often cutting only a few thousandths deep
[16:04:52] <Strogg> hrmm
[16:12:41] <tomp> any online sources for panasonic servos that have pricing? ( like 400W minas-mama )?
[16:37:46] <tomp> nevamind, I'll stick to AD ;-)
[16:38:00] <anonimasu_> active diretory?
[16:38:39] <anonimasu_> ew.
[16:49:57] <Hugomatic> Hello, I just used stepconf wizard on a Sherline mill and I have a problem: "joint 0 on limit switch error". Any documentation or quick fix for this? I don't have any limit switches. thanks
[16:51:09] <BeIdentityCrisis> @Hugomatic: go back through the wizard and the pins configured as limit switches set to unused.
[16:51:19] <cradek> in the parallel port setup in stepconf, ... that's just what I was going to type.
[16:51:40] <BeIdentityCrisis> Ha! I type fast....
[16:51:41] <Hugomatic> I remember seing those, right. thanks for the tip
[16:52:44] <BeIdentityCrisis> you could also invert them.... but I don't know if there is any point in doing that.
[16:56:37] <Hugomatic> Its looking good guys, thanks...
[17:05:33] <BigJohnT> tomp what are you needing?
[17:08:00] <Hugomatic> I still have a few problems using the ´╗┐stepconf wizard, but it is a great tool...
[17:08:59] <BigJohnT> Hugomatic: what kind of troubles?
[17:14:50] <Hugomatic> BigJohnT: 1) I didn't know that I had to disable the pins, for example. But now I see that I should have selected the Sherline Driver type in the first screen, and I would probably have had defaults that work "out of the box". 2) It is also not that clear why setting the axis config values affect the scale and Hz. I had to play a lot with the values...
[17:15:54] <BigJohnT> ok, I'm working on the manuals so I'm interested in this kind of feedback Thanks
[17:16:38] <BigJohnT> I'm making a checksheet that you can print out before running stepconf that will help gather the info you need when you run it...
[17:17:11] <Hugomatic> I wonder why changing the max velocity affects the Hz. Maybe if you just ad the formula to the wizard page, you won't have to write a manual.
[17:18:09] <Hugomatic> BigJohnT: did you write stepconf?
[17:18:19] <BigJohnT> I'm not sure at the moment I don't have a linux computer in front of me and stepconf is written by someone else
[17:18:50] <BigJohnT> I did the g code generators on the wiki site and am working on the manuals at the moment
[17:20:15] <Hugomatic> It's a great tool. While I'm at it: my mill is very inaccurate, and I am curious about the "Backlash". How do calculate it, and could stepconf be upgraded to do it for you?
[17:21:22] <rayh> The Hz required is equal to the number of pulses per unit times the number of units per second.
[17:21:25] <BigJohnT> backlash is something you don't want. I would put an indicator on each axis and jog small distances to see what it takes to move back and forth.
[17:22:19] <BigJohnT> hi rayh
[17:22:23] <rayh> So if you want a faster speed you must have have higher frequency.
[17:22:28] <Hugomatic> If I were to create a gcode program to move back and forth n times, and measure the final error, would that give me n * backlash?
[17:22:34] <rayh> Hi BigJohnT
[17:23:36] <BigJohnT> I've never done it that way but maybe someone else can chime in on that...
[17:24:38] <rayh> Backlash happens when ever a motor changes direction.
[17:24:44] <rayh> It is not cumulative.
[17:25:08] <Hugomatic> rayh: you mean 2 backlashes cancel each other?
[17:26:04] <rayh> Yes if you move an axis plus then minus they cancel out.
[17:26:37] <rayh> I test backlash say by moving an axis a bit in one direction.
[17:26:49] <rayh> That move takes out the backlash that way.
[17:27:08] <rayh> Then I set an indicator and move a bit further.
[17:27:29] <rayh> Then I move back to the original place and the indicator will show the lash.
[17:28:30] <Hugomatic> If you try to move "less" than the backlash, say 0.001, then you could accumulate the errors... but maybe I can calculate it like you do
[17:28:58] <anonimasu___> uh.. what kind of error is it you want to measure?
[17:29:06] <anonimasu___> backslash?
[17:29:06] <rayh> No they still do not accumulate. Backlash is a hardware thing.
[17:29:34] <anonimasu___> yep
[17:29:54] <Hugomatic> I'd like to calculate the backlash precisely, using a gcode program that could amplify it (I don't trust myself with measuring tools)
[17:30:07] <anonimasu___> then you are fscked.. there is no other way.
[17:30:08] <rayh> Say your leadscrew and slide have .003 backlash.
[17:30:19] <anonimasu___> if
[17:30:53] <Hugomatic> So you move 100 times 0.1 inch in the positive direction, and each time you move back 0.001 inch.
[17:30:54] <rayh> If you switch direction and move .001 you are about 1/3 of the way into the lash.
[17:31:36] <anonimasu___> you could do a 10mm move to one direction.. then do a 10mm move back.. and measure the difference
[17:32:09] <BigJohnT> Hugomatic: if you have 0.010" backlash and you move back and forth 0.005" nothing will move but your controls think that it did. As soon as you move in any direction at least 0.010" the table will move and it will be out of position by some or all of the backlash
[17:32:43] <Hugomatic> You guys are right, I don't think I can amplify backlash with n moves. This is good.
[17:33:10] <anonimasu___> Hugomatic: backslash dosent amplify with n moves.. however if you are losing steps it will amplify
[17:33:58] <rayh> Sounds right to me.
[17:34:41] <BigJohnT> Hugomatic: if you have .010" backlash you are never more than that out of position.
[17:36:52] <BigJohnT> Hugomatic: to see how good or bad it is chuck a pencil up and draw a circle on some paper with your mill, if it round enough for you no problem if not...
[17:38:28] <Hugomatic> That's a good tip, thanks.... I think my backlash worries were in all my head :)
[17:39:39] <BigJohnT> * BigJohnT heads off to my customers plant...
[17:39:48] <BigJohnT> ttul
[19:51:36] <tomp> rayh: your opinion... is Automation Direct as good as Panasonic? (lookin at 400W low inertia servos )
[19:56:29] <rayh> Yes
[19:57:06] <rayh> What kind of project do you have in mind for them?
[20:04:10] <rayh> tomp, I've always had very good service from AD.
[20:15:55] <Roguish> Tomp: i use AD also and like it.
[20:19:54] <tomp> rayh: 8 axis hole drill. mfctr sent pix with panasonics. mfctr does 2 axis, end user does 6 more.
[20:19:55] <tomp> ´╗┐i'd rather AD because they're readily available to end user.
[20:20:03] <tomp> i also have have success with AD
[20:20:47] <rayh> I like them a lot.
[20:20:54] <tomp> and AD is really Toyo, so available to mfctr in Taiwan easily
[20:21:12] <tomp> rayh: last comment sold me :)
[20:21:13] <rayh> There you go.
[20:22:57] <rayh> I was really impressed with some of the Panasonic stuff I saw last year at the Beijing tool show.
[20:23:17] <rayh> But it is pricey to get here.
[20:27:57] <chr0n1c> i really enjoy trade/tool shows and seeing all the awesome machines (free posters with bikini girls pawing the machines never hurts either)
[20:28:28] <chr0n1c> we have a neat show here at the dayton convention center every year and i get free passes most of the time
[20:28:30] <rayh> free posters AND bikini ...
[20:29:23] <chr0n1c> see rayh knows what's up ;)
[20:30:17] <archivist> I wonder why I go to shows
[20:30:26] <rayh> I think the regional tool shows are a better deal than IMTS these days.
[20:30:27] <archivist> eye candy
[21:11:08] <skunkworks_> anyone remember the max board size in free eagle?
[21:11:44] <chr0n1c> 3"x4" maybe?
[21:15:03] <skunkworks_> 4 x 3.2
[21:15:08] <skunkworks_> close :)
[21:15:19] <skunkworks_> That isn't very big.
[21:15:44] <skunkworks_> but what do you want for free.. ;)
[21:16:46] <archivist> the world
[21:19:25] <chr0n1c> there may be another free version of eagle that does bigger boards but i'm not sure of the legalities of it... which is why i have PCB installed
[21:19:50] <chr0n1c> of course the only and biggest board i ever designed so far was 1.5" x 3.5"
[21:20:13] <archivist> I tried kicad at xmas, has a few warts
[21:31:44] <chr0n1c> i haven't tried kicad yet, but PCB is nifty
[21:33:00] <archivist> kicads autorouter is rubish
[21:41:47] <jepler> I should invest the time to learn a Free pcb/schematic software. eagle is OK and I've learned it, but I'm starting to encounter the size limits more
[21:42:15] <jepler> (I bought the 100mmx80mm version, same size as their no-cost version but without the no-commercial-use restriction)
[21:43:18] <archivist> I could never handle a size restriction like that (pcb design was the day job some years ago)