#emc | Logs for 2007-10-24

[01:44:58] <toast> boy did i machine myself into a corner today
[01:45:07] <toast> how are you gents.
[01:48:03] <skinnypuppy34> Good toast, you?
[12:33:33] <Guest871> Guest871 is now known as skunkworks_
[13:09:36] <CIA-22> 03jepler 07TRUNK * 10emc2/lib/python/rs274/ (glcanon.py interpret.py): (log message trimmed)
[13:09:36] <CIA-22> a better fix for the "360 degree arc turns tiny" problem
[13:09:36] <CIA-22> The original problem was that the start and end points of certain 360
[13:09:36] <CIA-22> degree arcs would be different by a tiny amount (for example,
[13:09:36] <CIA-22> 1.0433070866141736 vs 1.0433070866141734) when offsets were in effect.
[13:09:36] <CIA-22> Originally, the case for this wasn't found. Instead, a small FUZZ
[13:09:40] <CIA-22> factor was introduced; circles that were smaller than FUZZ radians
[13:38:22] <cradek_> cradek_ is now known as cradek
[13:42:11] <fenn> I posted this earlier but in the wrong channel. It's a general overview of "why hexapods are cool" and why someone should give me money to git 'r done: http://fenn.dyndns.org/pub/emc/bfi/bfi-draft.txt
[13:47:40] <cradek> are you asking for input?
[13:48:24] <fenn> if you have something to say about it, sure
[13:48:41] <cradek> are you looking for investors or grants?
[13:49:19] <fenn> its a contest entry, but the idea is probably more important
[13:49:38] <fenn> i would rather get grants because i think investors would screw it up
[13:50:55] <cradek> you say "All of my work so far has been done with free and open source software tools so it can be distributed and used widely for no charge" and that causes two issues for me: the "so it can part" does not follow, since you can use free tools to make a non-free product. also, you don't say how you intend to license any future work or final product.
[13:51:04] <cradek> the "so it can" part
[13:51:36] <cradek> yeah if you want it to be Free, most investors will want to screw it up.
[13:52:07] <fenn> if you use non-free tools it's a huge pain in the ass for someone to come along and make a minor contribution
[13:52:50] <cradek> oh I think I see what you meant now
[13:54:01] <fenn> if it's not Free people will think it's a gimmick
[13:54:16] <cradek> I did not understand the whole sentence I guess
[13:54:47] <fenn> that's one of the hardest things to explain, for me, since it's not a technical issue
[13:54:57] <cradek> I read: "as an (accidental?) consequence of my use of free tools, my work can be distributed/improved"
[13:55:31] <skunkworks_> very neat. I have a growing hexapod 'itch'.. Great - another project.
[13:55:32] <cradek> when you meant "I used only free tools to make it most easily distributed/improved because that's my goal"
[13:55:59] <cradek> I agree it's hard to explain, especially succinctly
[13:57:23] <cradek> if you meant the second thing I said, the "so far" makes it really wishy-washy
[13:58:43] <fenn> ok, i reversed the wording
[14:01:34] <cradek> also I see some unnecessary negativity in "usually a pointless endeavor" and "to pursue a real career" - you should reword or just drop things that secretly let us know how you think you might fail
[14:03:23] <cradek> the rewording of "So that it can be" is much clearer
[14:03:49] <cradek> but the "so far" still leaves me wondering a bit
[14:06:01] <cradek> minor grammar problem in "They could be used for:... by rescue workers"
[14:06:15] <skunkworks_> cradek: what where you an editor for in your former life?
[14:07:08] <cradek> skunkworks_: I'm not an editor but I play one on TV
[14:08:30] <cradek> also "used for:... in physical therapy"
[14:09:39] <cradek> misspelling: "havent"
[14:10:09] <fenn> how do you explain what rescue workers do
[14:10:41] <fenn> does just 'rescue work' sound right?
[14:10:58] <fenn> emergency rescue
[14:11:25] <cradek> yes either of those I think
[14:11:41] <cradek> (I'm not sure what kind of rescue work you mean)
[14:12:02] <fenn> pulling cars and fallen buildings off of people
[14:12:56] <fenn> i guess i could just say that
[14:13:03] <cradek> brb
[14:21:18] <skunkworks_> hmmm http://www.prsco.com/
[14:23:25] <fenn> yeah those companies change names every few years..
[14:24:18] <fenn> cool a hexapod waterjet - i had that idea too
[14:25:34] <skunkworks_> the rotory one is pretty cool.
[14:25:40] <skunkworks_> differetn
[14:25:42] <skunkworks_> ent
[14:59:42] <skunkworks_> pentapod? http://www.metrom.com/video_d.html
[15:04:05] <skunkworks_> fenn: you should post info on your simulation here. http://www.cnczone.com/forums/showthread.php?t=753&highlight=hexapod
[15:04:26] <skunkworks_> bring it back to life. They had some odd ideas about how hexapods worked.
[15:04:35] <skunkworks_> not that I am an expert.
[16:37:10] <skunkworks_> how much harder is it to calculate the kins for a hexapode using universal type joints for the strut ends?
[16:44:04] <fenn> if you use coplanar swivels in the joint it should be the same calculation
[16:44:32] <skunkworks_> really? compared to a ball joint?
[16:44:38] <fenn> i think so
[16:45:17] <fenn> one problem is that rotation around the screw axis causes the joint to extend and retract
[16:45:18] <SWPadnos_> a U-joint should have some point where the two centerlines intersetc. that's the point you'd use as the joint origin
[16:45:28] <SWPadnos_> intersect
[16:45:51] <fenn> SWPadnos_: there are designs that have u-joints with skewed u-joint axles
[16:45:59] <SWPadnos_> those would be harder ;)
[16:46:09] <skunkworks_> ok - I was just thinking in a car drive shaft you need to make sure that you have both 'in phase' or it will pump.
[16:46:37] <SWPadnos_> if you put it together wrong, then all bets are off
[16:47:53] <fenn> i would like to be able to correct for all possible errors in the machine, even if it sounds insane
[16:49:25] <SWPadnos_> iut would be nice, but I think it may be a hard problem
[16:49:53] <skunkworks_> I am just trying to visualise. If I where to make one at the moment - I would have preloaded universal joints (timkin) on each end of the strut with the linear whatever device (ball screw) between. maybe have the universal joint hollow so that the screw could go thru it. and have the spinning ball nut at that point. \
[16:49:55] <SWPadnos_> actually, that should be "a Hard Problem"
[16:50:19] <fenn> you think it's that bad?
[16:50:31] <SWPadnos_> I think it might be
[16:50:52] <SWPadnos_> when yuo consider that every bearing or joint could be irregular / eccentric
[16:51:25] <fenn> there's only 32 centerlines in the machine
[16:51:25] <SWPadnos_> there are probably places where you get multiple or no solution
[16:51:54] <skunkworks_> The forward kinematics problem, a system of equations which given the leg lengths, yields the position and orientation of the platform, has up to 40 solutions. However, the inverse kinematics problem (i.e. given the position and orientation of the platform, find the required leg lengths) has a unique and very simple solution.
[16:51:58] <SWPadnos_> dunno. I have a cold, and I haven't had much coffee, so I don't think my visualization engine is at 100%
[16:52:03] <skunkworks_> that is interesting.
[16:52:30] <skunkworks_> http://en.wikipedia.org/wiki/Stewart_platform
[17:16:36] <skunkworks_> fenn: http://www.delphion.com/details?pn=WO09928097A1
[17:18:35] <fenn> meh
[17:18:42] <skunkworks_> :)
[17:19:59] <skunkworks_> very stupid question... Is there a calculater out there that you can enter strut sizes, movement, and centers to get it maximim work envelope?
[17:20:06] <skunkworks_> besides my own calculator?
[17:20:07] <skunkworks_> ;)
[17:20:47] <fenn> nothing convenient i'm sure
[17:21:14] <fenn> http://hexapod.zemris.fer.hr/engleski/calc/
[17:21:50] <skunkworks_> ooh - that looks interesting. thanks
[17:23:28] <fenn> the cross section thing is cool
[17:32:44] <skunkworks_> fenn: very cool. I love the 'cloud' work area it shows in vrml. Gives me a good idea of what envelope you have.
[17:35:11] <fenn> what are you using to look at the vrml?
[17:37:54] <skunkworks_> I just did a quick search and found this one http://www.parallelgraphics.com/products/cortona
[17:38:09] <fenn> its really lame how quickly vrml has sunk into obscurity
[17:41:17] <skunkworks_> fenn: http://www.electronicsam.com/images/KandT/hexapodworkarea.JPG
[17:43:42] <fenn> Hexapod by Leonardo :)
[18:25:11] <skunkworks_> yah - that site is going into my favorites.
[18:25:16] <skunkworks_> Thanks again fenn
[18:34:51] <skunkworks_> although it seems to be down now..
[18:35:25] <skunkworks_> I think I broke it
[18:37:13] <skunkworks_> oops
[18:46:40] <SWPadnos_> SWPadnos_ is now known as SWPadnos
[23:19:22] <chr0n1c> woohoo cnc!
[23:20:57] <skinnypuppy34> I'm making some .2 pitch pulleys, getting there...
[23:21:14] <JymmmEMC> woohoo gun!
[23:26:11] <fenn> skinnypuppy34: hobbing them?
[23:27:22] <skinnypuppy34> Just turned a blank, going to single point cut them with the dividing head
[23:28:21] <skinnypuppy34> Blanks 6061
[23:31:39] <chr0n1c> i get outbid on every damn lathe i bid on...
[23:31:44] <skinnypuppy34> Looking at the xl belt tooth profile in machinerys handbook looks like a single point could be ground in a few minutes.
[23:33:18] <skinnypuppy34> Keep on chr0n1c my 17" swing clausing + 3 and 4 jaw and burnerd quick release collet and chuck set for only $1000 on ebay and a $250 flat bed tow
[23:33:52] <chr0n1c> i have been looking at 9", 10", 12" machines...
[23:34:06] <chr0n1c> something small, but able to do most things still
[23:34:14] <skinnypuppy34> Where ya at?
[23:34:18] <chr0n1c> *that i would need to do
[23:34:23] <chr0n1c> dayton ohio
[23:34:44] <chr0n1c> i have only been looking on ebay
[23:34:47] <skinnypuppy34> You should see something regularly I would think. Been a few months since I've hunted
[23:34:51] <chr0n1c> yes...
[23:34:54] <skinnypuppy34> craigslist sometimes
[23:35:10] <chr0n1c> today i found 387 brake rotor lathes when i searched
[23:35:11] <chr0n1c> lol
[23:35:28] <skinnypuppy34> I've seen two or three in driving distance in the last few months...
[23:35:38] <chr0n1c> there must have been some big advance in brake rotor lathes recently
[23:35:51] <skinnypuppy34> No idea...
[23:36:07] <chr0n1c> i'm going to keep looking....
[23:36:24] <chr0n1c> it's not something i need need need right now... so i have some time
[23:36:59] <skinnypuppy34> Yeah I understand. I've been hunting a toolroom quality lathe. without paying an arm and leg
[23:38:24] <fenn> machinery auctions are often advertised in the sunday paper
[23:38:44] <fenn> you live in ohio so it should be easy
[23:38:55] <chr0n1c> we get notices at the shop... if i can get to them before the boss tosses them...
[23:39:12] <chr0n1c> he throws away all the good bathroom reading material
[23:47:34] <skinnypuppy34> WIsh this machine had been a little closer.
[23:47:38] <skinnypuppy34> http://cgi.ebay.com/Hardinge-Lathe_W0QQitemZ120173350285QQihZ002QQcategoryZ104241QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
[23:49:27] <dmess> hi all
[23:49:38] <chr0n1c> yo mess
[23:49:48] <dmess> http://www.fa22raptor.com/ if you have a good connection grab the video frol the Langley Va air show.... AWESOME bird... but looks like a flying wood duck to me...
[23:50:22] <dmess> yo cr0n1c
[23:50:39] <chr0n1c> that looks like a nice lathe to have around
[23:50:55] <dmess> is it still available??
[23:51:13] <skinnypuppy34> It didn't sell, email the seller
[23:51:49] <skinnypuppy34> I'd probably pester him if it were a bit closer
[23:52:00] <dmess> where are you??
[23:52:08] <skinnypuppy34> Middle georgia
[23:52:34] <dmess> its in alabama?? right??
[23:53:49] <skinnypuppy34> Wedowee,Al
[23:54:00] <dmess> whats al
[23:54:07] <dmess> alaska??
[23:54:11] <skinnypuppy34> Alabama
[23:54:28] <skinnypuppy34> I could be mistaken
[23:55:02] <dmess> shite for 500 bucks i could have it droped anywhere in georgia
[23:55:19] <dmess> if ts in alabama
[23:55:48] <skinnypuppy34> dmess I'll keep this in mind for the future
[23:55:49] <dmess> small machine.. fits in pick-up...
[23:56:30] <dmess> some good friends would bring it home to me for free... ;\)
[23:56:52] <skinnypuppy34> Oh reallllyyyy ... didn't realize it was quite that small
[23:58:08] <JymmmEMC> Does anyone know a good source for used/surplus Ice Maker parts?
[23:58:22] <JymmmEMC> commercial ice maker
[23:58:23] <dmess> but works ANYTHING to aprox. 12 inches with the right tooling...
[23:59:13] <dmess> call the local ice maker.. ask him where he finds part.. unless thats YOU
[23:59:24] <skinnypuppy34> If you're interested get it by all means, my wallet needs to recover from motors/geckos/powersupply/wires/belts in the last month
[23:59:49] <JymmmEMC> dmess: That's the problem the comany is no longer in business and they want premium price for the parts.