#robotics Logs
Aug 04 2012
#robotics Calendar
00:02 tobbor Possibly http://eds.dyndns.org/~ircjunk/projects/reprap
00:02 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040423.jpg <-- that was the test piece
00:03 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040426.jpg <-- large test build
00:03 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040428.jpg <- uncleaved prototype
00:03 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040429.jpg <-- first proto
00:03 GuShH people may think you are making meth pipes!
00:05 rue_mohr I'll file them with the prople thinking my heating boiler makes moon shine
00:05 rue_mohr where did kat go?
00:11 GuShH oh so it doesn't make moonshine?
00:11 GuShH what a shame.
00:11 rrywolf curls up on kat's bed to wait for her, as it's wolfy bed
00:12 furrywolf bbl
00:48 eless looks at furry like he's not here ei
01:10 rue_shop oh kat, what now?
01:11 rue_shop I'm gonna try to use my cnc machine to drill a #80 hole thru brass
01:11 rue_shop I have 50 carbide #80 bits
01:11 rue_shop of the moment
01:12 useless earlier today, i said something, so bear left and furry quit talking
01:12 useless being i got up at 3am today, it's noteworthy that only Tom has spoken to me
01:19 useless like now
01:25 ShH stares at use
01:40 rue_shop ok I broke the first bit
01:51 GuShH rue_shop: moar lube, moar speed!, and slower movement!
01:52 GuShH (if it's just a hole, you'd want to slow down and let the bit do it's thing, assuming they're new and not blunt used shit)
01:53 GuShH some people buy used bits off ebay.... the ones they discard from pcb fab houses for example.
01:55 rue_shop ok the second bit broke, but it went thru first
01:56 rue_shop my cnc it stepper based, I set it to FREAKING SLOW
01:56 rue_shop gave it a pool of oil
01:56 rue_shop my bits are new
01:57 rue_shop but I have a hole
01:57 GuShH minus 2 bits >_<
01:57 GuShH moar speed!
01:57 GuShH are you using a router for the head?
01:57 rue_shop no
01:57 GuShH is the bit vibrating / off center?
01:57 rue_shop its a weed eater motor with spped feedback
01:58 GuShH o.o
01:58 rue_shop it would have cost $4 for those bits, but they were free
01:58 rue_shop I'll ebay 10 off to pay for soemthing
01:58 GuShH I would imagine those weed eaters are not built with tight tolerances
02:00 GuShH had this crazy idea the other day for using a regular vacuum motor to both drive a tool and suck the debris out at the same time, but I figured it would be too wiggly and useless.
02:04 rue_shop it holds pretty good
02:04 rue_shop I think I replaced the ball bearings in it as some point when I was setting it up
02:05 GuShH I hate electric weed eaters!
03:59 rue_mohr http://www.youtube.com/watch?v=j0hHsMvqHQo&feature=related <-- fail
05:53 rue_shop3 ok
05:53 rue_shop3 I made the heater block
05:53 e_shop3 swaggers and looks at the clock with one
05:53 rue_shop3 !time
05:53 tobbor My watch says its 03:52 Sat Aug 04 2012
05:53 rue_shop3 clock is wrong by 10 mins, huh
06:21 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040430.jpg
06:21 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040431.jpg
06:22 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040433.jpg
06:22 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040435.jpg
06:22 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040437.jpg
06:22 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040438.jpg
06:22 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040439.jpg
06:23 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040441.jpg
06:23 rue_mohr http://eds.dyndns.org/~ircjunk/projects/reprap/p1040442.jpg
06:24 rue_mohr last image there is the heater block
06:27 chris_99 what are those rue_mohr
06:42 rue_bed parts for the extruder head of the reprap I'm making
06:49 Triffid_Hunter rue_bed: where's the thermistor go?
11:01 furrywolf ... when did I stop talking to you?
11:01 furrywolf you mean when I looked at the clock, saw I was late for work, said something along the lines of "bbl, work", and ran to the car?
11:04 furrywolf also, I didn't see you here. to check if you're here, I hit kat<tab>, and if nothing happens, I assume you're not here. I don't whois everyone to see if one of the nicks is you under a random self-derogatory name.
11:05 furrywolf and, now I need to take off again. bbl, leaving irc for reasons completely unrelated to anything you've said, namely that I volunteered to help with the electrical on the little tourist train the museum has.
11:06 useless k
11:07 furrywolf I've never done electrical on a train before. you learn something new every day, right? :)
11:07 furrywolf bbl
11:08 katsmeow-afk it's prolly a 1960's small car underneath
12:11 katsmeow-afk speaking of fridges, there's a 5ft tall ammonia propane-120v fridge-freezer at the recycler, but it has some rust on the steel line from the boiler, so it's not stainless
12:12 katsmeow-afk meaning it could rust thru, if it hasn't already, and blow a huge cloud of ammonia
12:14 GuShH fun
12:36 rue_bed Triffid_Hunter, I'll screw, epoxy, or tape it to there somewhere
12:36 rue_bed !time
12:36 tobbor My watch says its 10:35 Sat Aug 04 2012
12:36 rue_bed !math 10-3
12:37 rue_bed i havn't done that yet?
12:37 katsmeow-afk nope
12:37 rue_bed 9 8 7, 7 . 8 . 9 . 10 its 7
12:37 rue_bed 7 hours sleep
12:37 rue_bed ok
12:39 tsmeow-afk points ,, hell, never
12:39 rue_bed points?
12:39 e_bed looks ar
12:39 katsmeow-afk raise arm, straighten a finger, align it to theline of sight to an object
12:40 katsmeow-afk garf
12:40 e_bed checks to make sure he has clothe
12:40 rue_bed ohl, there
12:55 furrywolf katsmeow-afk: 1953 ford, if I remember right. :)
12:55 furrywolf well, it's an actual railroad car, with a 1953 ford engine/trans linked to it with a big chain.
12:56 katsmeow-afk such a thing was real comon for real use in the usa west once, and on "abandoned" rail lines in rural Oz too
12:56 furrywolf we classified the problem as "unable to reproduce"... complaint was the rear horn was intermittant, and would stop sounding if the front horn was used. all grounds seem solid, and we couldn't reproduce the problem.
12:57 katsmeow-afk ground to body or chassis? <,< >,>
12:58 furrywolf neither. straight to battery.
12:58 furrywolf horns are mounted on plywood
12:58 katsmeow-afk plywood is not a ground
12:58 furrywolf correct. hence why they have a wire than runs back to the battery. :)
12:58 furrywolf through a few plugs, all of which checked good.
12:58 katsmeow-afk the gnd wasn't fastened under the bolt that fastens the horn to the playwood, right?
12:59 furrywolf the symptom strongly suggests a bad ground, but we couldn't find it.
12:59 rue_bed or horn failure
12:59 katsmeow-afk plywood dries out, shrinks, connection broken
12:59 furrywolf rue_mohr: pressing one causes the other to stop is bad ground, not bad horn
12:59 furrywolf bbl, someone out front
13:00 rue_bed oohl, I mrs Understood
13:00 katsmeow-afk pressing one causes the other to stop is a spdt switch
13:01 katsmeow-afk saves power to run only one at a time,a nd really screws with the doppler effect when the train is moving
13:02 katsmeow-afk "noise ordinance says you can run only one horn at a time, you will need to put a horn on every car and cycle thru them"
13:02 rue_bed Triffid_Hunter, I have an industrial thermal controller with some k type thermocouples I'm wondering how I could use
13:02 katsmeow-afk _ _ _ _ beep
13:02 katsmeow-afk _ _ _ beep _
13:02 katsmeow-afk _ _ beep _ _
13:02 katsmeow-afk _ beep _ _ _
13:02 katsmeow-afk beep _ _ _ _
13:03 katsmeow-afk back and forth
13:03 rue_bed mmm it reached the end whats it going to do now
13:03 katsmeow-afk imagine a train with 30 cars doing that as it passes you
13:04 e_bed thinks of his lost locomot
13:04 rue_bed I like switchers best
13:04 rue_bed 040
13:05 tsmeow-afk thinks locomobile, ambulance, and car all relate to the same human conveyance de
13:06 katsmeow-afk i need breakfast, and by the time that's prepared, lunch will be late
13:08 katsmeow-afk heck, if i had 30 friends with cars, i'd work up a scheme for blowing their horns in sequence, with no gap in the sound, fast, and drive thru town once or twice with the system and a google camera to record the humans witnessng the event
13:09 katsmeow-afk 30 cars take up 1500 ft when moving thru town at speed limit or slower
13:11 katsmeow-afk figure a horn toot on each car lasting 1/2 sec, that wold make the sequence time from end to end slow enough people would do swivel heads looking at sound sources, and still be fast enough to avoid close localisation
13:12 katsmeow-afk it would be like a cat video but with humans
13:13 katsmeow-afk like drawing on clouds with a laser (which you cannot do now because pilots get blinded)
13:34 rue_mohr I can think of parallel and series circuits where that would happen
13:39 rue_mohr I'm gonna open todays package now!
13:40 rue_mohr push on pipe coupler!
13:44 lostcauz I ordered a shaft coupling and it doesn't fit on the octagon shaped auger side. I checked my measurements and realized I measured flat to flat instead of corner to corner. I reckon I'll go fire up the grinder!
13:44 rue_mohr heh good one
13:44 rue_mohr remember to grind evenly
14:07 Tom_itx or turn it round in a lathe
14:07 lostcauz I don't have a lathe
14:07 Tom_itx you should
14:07 rue_mohr make a lathe!, to do this, you will need a) a lathe...
14:07 lostcauz Yes, I should.
14:10 lostcauz Oh, it's a hexagon shape! Good, less corners
14:15 katsmeow-afk but corners are easier to grind, there's less metal
14:37 lostcauz Mental note: Never give family entry code to ones shop.. *waiting on brother to drive over with my grinder he borrowed when I was away*
14:38 lostcauz katsmeow-afk, yeah shouldn't take long, gotta cut off the screw tip as well.
15:27 katsmeow-afk i scheduled outside work pulling fence posts up etc today because temps were forecast to be in the high 80's,,,,,, it's now 93F with a heat index of 103F
15:33 rue_mohr http://www.thingiverse.com/image:138022
15:33 rue_mohr hahah someone abandoned their trainset
15:33 rue_mohr :)
15:34 katsmeow-afk train set?
15:34 rue_mohr look carefully in the image
15:34 rue_mohr I think its N scale
15:35 katsmeow-afk ah, looks smaller than HO for sure
15:35 katsmeow-afk or, H0
15:36 rue_mohr I always said ho
15:36 katsmeow-afk the next higher guage in the uk system is H1 tho, then H2 , so it had to start with Hzero
15:37 katsmeow-afk i always said Ho too, till i found out everyone was telling me wrong
15:37 katsmeow-afk but i still say power flows from - to + , regardless of "hole flow"
15:38 rue_mohr it implies an array of H scales
15:38 katsmeow-afk thereIS an array of H scales tho
15:38 rue_mohr my electrons flow from + to -, even tho they do so backwards
15:38 rue_mohr I thought HO was "Half O"
15:38 rue_mohr as in , half O scale
15:40 tsmeow-afk tries to stay out of it, cause she has no stuff in that f
15:42 katsmeow-afk one grandfather was into Trains, he worked for a railroad, i emember there being Lionel Super-O , O27, O , and HO
15:44 katsmeow-afk seemed to be an O fixation
15:46 katsmeow-afk Why Model Railroad?
15:46 katsmeow-afk An overview of some of the benefits to model railroading. (revised 01/23/01)
15:46 katsmeow-afk I cannot afford a real railroad, and it won't fit in my apartment
15:47 tsmeow-afk waits on rue to use antigrav to put a model railroad on the underside of his bed, over the desk, running upside
15:56 katsmeow-afk layout on steel plate, and superstrong magnets
15:57 stcauz runs to the patent office with kats ide
15:59 katsmeow-afk you might as well, other people have :-/
16:00 lostcauz lol, I would never, sorry to hear you have been burnt though.
16:10 katsmeow-afk i useto read encyclopedias, one day i was reading one, and after reading one sentence, my brain convulsed, i remembered a sentence in another volume, and a sentence in a volume i had read a month before, and i sat all 3 books upen to the sentences, went to the store, came back with red peppers and a spray bottle, and made the first ever (what would be known as) CapsacinP
16:12 katsmeow-afk i went back for some other stuff because i had another invention, and the pharmacist asked me what i was doing, and i told him, and he retired from there the next week, and went to some sorta new bio company
16:12 katsmeow-afk in 6 mo, CapsacinP was in the news
16:12 katsmeow-afk i have never told anyone what the other invention was
16:15 lostcauz that's interesting
16:16 katsmeow-afk and it galls the hell outa me that the poeple who laughed at me, said i was wasting time, would now buy the stuff from someone else
16:17 katsmeow-afk hell, rue just shot me down on something else this morning, despite there being a perfectly good list of great reasons to have The Thing, because of his fondness for trees, and i becha one day he'll pay someone else too
16:19 katsmeow-afk i have a history of doing visual object recognition and measuring with video camera, but that got shot down because the DA's office says i cannot use any camera (still or video) on my property because it violates the neighbor's dog's right to privacy, and i cannot get a lawyer to refute that
16:21 katsmeow-afk i am scared if i use a video camera on a stick to get a good look at my back to look for ticks i pick up while putting up fence, i could be arrested
16:34 rue_shop3 then I suggest you dont do it that way
16:34 rue_shop3 otherwise you will be stressed
16:34 katsmeow-afk what?
16:34 katsmeow-afk how else will i find a tick maybe 1/10 diameter anywhere on my back?
16:36 rue_shop3 would rubbing alcohol on your back point out any problems quickly?
16:36 katsmeow-afk i dunno
16:36 rue_shop3 usually does for me
16:36 rue_shop3 every little scrape
16:37 katsmeow-afk you spash rubbing alcohol on your back every day?
16:37 rue_mohr no, every so often with my hands
16:38 katsmeow-afk i cannot get my hands all over my back, my shoulders are worn out
16:41 rue_mohr anyone can hold picassos brush, but only he was screwed up enough to paint what he did
16:42 tsmeow-afk points to 2 boxes of video camers, some over 10 yrs old, never used,,, my "picasso" would be to USE them for valid purp
18:31 furrywolf http://www.eastcoasttoolsma.com/index.php?main_page=product_info&products_id=10575 any chance someone here has one of those they'd like to sell?
18:31 furrywolf (1/4" ratchet adapter)
18:31 furrywolf doesn't need to be snapon, but if it isn't, don't ask snapon prices. :)
18:34 furrywolf I only have a 1/2" one, need a tiny one...
18:37 Triffid_Hunter rue_bed: some people use type K thermocouples in combination with max6675 or ad595 chip, they can't be hooked directly because the signal level is too low for the atmega's ADC
18:38 rue_shop I know that....
18:38 rue_shop but I didn't know about the max6675 ad595 chips, the maxim ones prolly expesive
18:38 rue_shop come to think of it, I think I have a ad595
18:39 rue_shop I let apt autoremove a bunch of stuff, but I backed up the list of stuff it took out, and the window manager I like is gone
18:39 rue_shop I cant find the list
18:39 rue_shop aha
18:39 furrywolf bbl, working on cars
18:40 Triffid_Hunter rue_shop: fwiw max6675 is significantly cheaper than ad595 if you can't find it
18:56 rue_shop huh
18:57 rue_shop I have a box labeled "stuff that might come in handy some day" which I'm sure its in
19:11 rue_shop Triffid_Hunter, do you know the Rz and b of your temp sensor?
19:12 Triffid_Hunter rue_shop: R(25) is 100k, beta is 4066
19:14 rue_shop hmm, the ones I have have betas of 3380 3477 2362 3477 3245 3869
19:15 rue_shop my r(25) is around 8k to 9k on all of them
19:16 rue_shop so yours is higher resistance and falls off faster
19:17 Triffid_Hunter rue_shop: yes
19:17 Triffid_Hunter rue_shop: we need them to have a usable resistance and curve steepness in the 160-240c range
19:17 Triffid_Hunter at 200c they're less than 1k from memory
19:17 dumbass furry : i now know why it takes so much out of me to swing my sledgehammer, and why doing so for so many years contributed to damage of my shoulders: it's a 16 lb hammer
19:18 rue_shop yea, by then, mine are aroud 700 ohms or lower
19:18 Triffid_Hunter rue_shop: also, most thermistors are only good to 125 or 150c, we need ones rated to 300
19:19 rue_shop I dont think any of the ones I have here WERE pulled from laserjets...
19:19 e_shop looks around
19:20 dumbass laserjet : 12megawatt recirc copper vapor laser on a 747
19:28 rue_shop heh
19:28 rue_shop no, sorry, I been branded
19:28 rue_shop laser printer
19:28 rue_shop ok now that I'm holding one, I realize I have a pile of them in the 'sensors' box
19:29 rue_shop anyhow
19:29 e_shop meas
19:33 rue_shop ooo 202k
19:34 Tom_itx first glade tutorial completed
19:38 dumbass air fresheners have tutorials?
19:38 atom1 this one does
19:39 moriarty dumbass, they cater for the likes of you too
19:39 dumbass goodie
19:39 moriarty :P
19:40 moriarty kind of reminds me of those transparently packaged nuts that has a warning label that cautions people what it contains
19:41 dumbass well, if you can read it, it isn't transparent, so you need a warning lable to tell you about what the warning lable is hiding
19:44 moriarty true, why didn't i think of that
19:46 dumbass they should put a warning label directly on the peanuts concerning the toxic dye used in the warning label on the peanuts
19:46 rue_shop Triffid_Hunter, hows this one: b 4288 R(0) 915719 [r(26) 234000 ]
19:46 moriarty haha dumbass
19:47 rue_shop hah Triffid_Hunter thats actually better than yours isn't it?
19:48 Triffid_Hunter rue_shop: dunno, 234k might mean your readings at low temp are useless. reprap firmwares refuse to start the heater if it's reading 0 as a safety measure
19:48 rue_shop http://rlv.zcache.com/caution_sign_has_sharp_edges_poster-r2dc13288349b4aa090e31047dd2d6d3a_a5cb_400.jpg
19:48 Triffid_Hunter can always try it and see
19:49 rue_shop I suppose lightening up on the pullup would mean rewriting the firmware
19:50 Triffid_Hunter rue_shop: nope just drop in another temperature table
19:51 Triffid_Hunter rue_shop: the firmware itself does linear interpolation with a look-up table to approximate the nonlinear curve that the thermistor gives, pretty simple stuff
19:51 Triffid_Hunter and if you ask 'calculator?' in #reprap, the channel bot will give you a link that'll calculate a temp table for any thermistor/pull-up combo you like
19:51 rue_shop yea, I'm gonna put the webpage for calculating the r0 and beta on my site, cause for some reason its not found on the internet dispite the code being right there in the howtos
19:52 dumbass you know a resistor pullup is going to make the curve nonlinear even if the temperature/resistance curve is linear? Plus, using a resistor pullup, a high current when the sensor value is low can cause sensor heating, making an error
19:52 Triffid_Hunter rue_shop: http://calculator.josefprusa.cz/ contains a javascript port of some python originally from hydraraptor.blogspot.com
19:53 rue_shop the javascript code is not found on the internet active that you can type the numbers in
19:53 dumbass an actual active current source pullup (or pull down) will be best
19:53 dumbass bbl
19:53 rue_shop kat, at 230c, stuck to a 20W resistor, the error will be negliable
19:56 Triffid_Hunter we don't need much accuracy, just enough precision to keep the PID loop happy :)
19:57 Triffid_Hunter I reckon my nozzle sensor reads about 15-20c low, but my prints are still goregeous
19:57 Triffid_Hunter just need to find number that works and stick with it
20:29 rue_shop from what I understand making one of the first prints a spare set of extruder gears is a wise idea
20:30 Tom_itx or print a mold and pour one from aluminum
20:31 rue_shop or I could just mod the thing to use the metal gears from a HP printer
20:44 GuShH it scares me how much alike I am to this guy... http://www.youtube.com/watch?v=NvrL1sj0OWc
22:13 dumbass what kind of gears do fishing reels have in them?
22:39 gaze__ hey guys! I need to build a high speed focuser... meaning I need to move a tiny lens in and out by a displacement of about 6 millimeters as ridiculously fast as possible
22:39 gaze__ besides voice coils, what other options are there?
22:39 gaze__ I suppose piezo motors? Maybe a high speed stepper like in old hard drives?
22:40 dumbass 6mm is a lot for a direct drive piezo
22:41 gaze__ yeah... and beyond direct drive these ultrasonic motors are really expensive.
22:41 dumbass a 1 inch vc will maybe move it under 0.001 seconds, depending on magnet and drive power
22:42 gaze__ yeah. a voice coil has to be the way to go
22:43 gaze__ So then my question is... http://www.ebay.com/itm/Moticont-Linear-Voice-Coil-Motor-LVCM-025-038-04B-/120953702329?pt=LH_DefaultDomain_0&hash=item1c296707b9#ht_852wt_1393 Where can I find one of these for less than 75 bucks?
22:43 gaze__ they don't seem that complicated.
22:44 dumbass use something else, rue made a avr-controlled one
22:44 gaze__ hahaha... I could literally use a voice coil... an old speaker
22:45 gaze__ I have a blackfin I can do state space control with... not worried about the electrical aspect... or even the coil. I'm more worried about the magnet.
22:45 dumbass well, they are delicate, and you need an iron core, but they'll stand up to being driven at 10Khz easy enough
22:47 dumbass some microservos are pretty fast too
22:47 dumbass and only a few bucks
22:47 dumbass if you have nearly zero weight to move, you could maybe remove some of the gear redustions from a micro servo
22:51 gaze__ ahh... those are gonna be noisy as hell
22:51 gaze__ and the thing is going to be mounted on a cross-roller slide
22:51 gaze__ so there's a little friction
22:52 gaze__ thing needs to be really well constrained in all but the degree of freedom I want to move in.
22:52 dumbass mass/weight is more of an issue at high speed
22:53 dumbass you did say ridiculously fast as possible
22:53 dumbass you can quiet a servo down if you run a thicker grease wher they have 5wt oil, or no oil
22:53 gaze__ yeah well... I still am not totally sure what the timescale of my galvanometer's travel is... this should match that
22:54 gaze__ lemme see
22:55 gaze__ well... the galvanometers have a small angle step response time of 1.5 milliseconds
22:55 gaze__ I'm not sure what that means for the full travel
22:56 dumbass 0.10 sec / 60 degree rotation using 6v , metal gears , 85 cents, free s&h
22:57 dumbass 0.10 sec / 60 degree rotation using 6v , plastic gears , 15 cents, free s&h
22:57 dumbass obviously you do not need full 60 degree rotation if the arm is long enough to travel 6mm at it's tip
22:58 dumbass so it's fair to say 6mm in 0.1 sec is ridiculously fast as possible for cheap as possible
22:59 furrywolf yay diesel! we were driving a recently purchased car, and found out that when the fuel gauge reads 1/8th, the tank is bone dry. we were contemplating the long hike to the gas station, when I remembered we had two quarts of spare motor oil in the trunk. :)
22:59 gaze__ the accuracy isn't that good.
22:59 gaze__ I guess if I add feedback or something
22:59 gaze__ but then there's backlash nearing the scale of the movement
23:00 dumbass yo ran the engine on crankcase oil?
23:00 gaze__ I mean.... cheap is good, but I'm willing to put up to 500 bucks into this
23:00 dumbass remove backlash with a spring
23:00 furrywolf dumbass: correct
23:00 dumbass damn,, i'll sell you those 85 cent ones for $500, no problem :-)
23:01 gaze__ oof... that's such a complex mechanical system.
23:01 dumbass furry : i now know why it takes so much out of me to swing my sledgehammer, and why doing so for so many years contributed to damage of my shoulders: it's a 16 lb hammer
23:01 dumbass this is complex?? ==>> http://www.ebay.com/itm/MG90S-Metal-Gear-RC-Micro-Servo-9g-for-450-RC-helicopter-/251122173747?pt=LH_DefaultDomain_0&hash=item3a780c4733
23:02 rrywolf realizes dumbass is kat, and s
23:02 dumbass thinking cutting off those two dead limbs over my driveway by use of a robot, that makes me a dumbass
23:03 furrywolf would be nice if people selling cars mentioned things like "by the way, the gas gauge doesn't work, and 1/8th is actually empty"...
23:05 dumbass and the rear leaf has a broken one, the fuel lines leak, both kingpins are shot and the bores are now 1/16 oversized, and two brake rotors ar paperthin, and we put gunk in the hydraulics
23:05 GuShH dumbass: cheap reels use stamped steel, good ones use brass or similar usually, and you'll find things are mounted on proper bearings with proper counter-weights, etc.
23:05 gaze__ I mean a spring only really works to take out backlash if you get the strength right for the amount of inertia
23:06 gaze__ I think a voice coil is really the only way to go
23:06 dumbass i am not gonna build it for you till i see that $500, gaze
23:06 GuShH furrywolf: my gauge doesn't work... it's the float I think, and you have to take apart half the car to replace it, that is if you can find the spare.
23:06 gaze__ I mean it's what's used in cd-rom drives
23:06 GuShH it lives most of the time at full or near full, but I'm certain the gauge itself is not damaged, haven't tested it yet though
23:07 dumbass yeas, and they are known for being speedy <eye rool>
23:07 GuShH furrywolf: do you have experience taking out dents on bodywork?
23:08 GuShH I should take a picture to show you actually, it's a compound creased son of a. I don't think I can heat treat and pump it out, I also think paint will flake right out if I try to push it back from the inside panel.
23:08 ShH sighs and thinks all rear-ending assholes on useless SUVs should be
23:10 gaze__ ok so if it's 0.1 second over 60 degrees, then it's 0.6 degrees over 0.001 seconds as a crude approximation which is what I need... then you need a 0.6/360*2\pi*r = 6 milli meter of displacement, making r half a meter
23:10 gaze__ that's completely silly
23:10 gaze__ a tiny servo cranking a half meter arm
23:11 dumbass you need it to move 6mm in .001 sec?
23:11 furrywolf I hate bodywork.
23:11 furrywolf I have experience beating it with a hammer then covering it with bondo to hide the horrible mess.
23:12 furrywolf voice coils sound like your only option.
23:12 gaze__ I mean ideally
23:12 dumbass yeas, i didn't realise we were talking 6mm in .001 sec
23:13 dumbass you taking 1000 pics/sec , all at different focusses?
23:13 gaze__ I'm using 1 millisecond as a timescale... since it's the small angle response of the galvanometers. I'm not sure how fast it can get from left to right
23:14 dumbass i'm pretty sure you can't see it move 6mm in .001 sec, os to read the meters, you're outa luck
23:14 gaze__ well... the point of this is to avoid using an f-theta lens in a laser scanning setup
23:14 gaze__ I need a flat focal plane
23:15 dumbass ok, your lens will eat up the $500
23:15 gaze__ nawwww. 30 bucks. It's a tiny lens.
23:15 gaze__ little 6 millimeter convex thing on edmund's optics.
23:15 gaze__ they're cheap.
23:16 furrywolf moving a lens back and forth at 500hz is going to make this assembley horribly loud.
23:16 furrywolf does it need to be linear motion, or controllable? would a simple crank and rod work, giving continuous sinusoidal movement?
23:16 dumbass and the bandwidth of the return signal will be pretty high too
23:16 gaze__ controllable. It's not making the full travel all the time
23:16 gaze__ I just need to know it's not going to limit the galvanometers.
23:16 gaze__ because that'd be a disaster.
23:17 mbass wonders if we mean the same by "galvanome
23:17 gaze__ galvanometer as in the same thing that moves the beam around in a laser light show
23:17 dumbass arg, that's a mirror
23:17 dumbass http://en.wikipedia.org/wiki/Galvanometer
23:18 gaze__ http://en.wikipedia.org/wiki/File:DynAXIS_L.jpg
23:18 gaze__ like this.
23:18 gaze__ pictured in the article
23:19 dumbass that turns the mirror, it doesn'tmove alens back and forth
23:19 gaze__ it'll mostly be making very small movements as the beam traces around something
23:19 gaze__ nono
23:19 gaze__ err
23:19 gaze__ yeah it does exactly that
23:19 gaze__ but it scans the beam angularly
23:19 mbass
23:20 gaze__ so if you put focusing optics BEFORE the galvanometer, you have a focal sphere section rather than a focal plane
23:20 gaze__ I plan on sticking a motorized lens in there that corrects for that
23:20 gaze__ plus, for stereolithography, it's nice to be able to knock the beam out of focus a controlled amount for doing infill.
23:20 furrywolf scan the beam across a funky tapered lens with a different focal length at each spot along its length, and of large enough overall size that the error in focus from one side of the beam to the other is not a problem. :)
23:20 dumbass why not an assy with two of http://en.wikipedia.org/wiki/File:DynAXIS_L.jpg in series, 90 degree to each otehr?
23:21 gaze__ furrywolf: That funky tapered lens is called an f-theta lens, and they're 5 grand.
23:21 gaze__ dumbass: That's exactly my setup. Again, you get a focal sphere.
23:21 gaze__ you need to correct for depth with either a f-theta lens, or a z-shifter
23:21 gaze__ a z-shifter is what I'm designing and building.
23:22 gaze__ if you have two galvos, the focal point will be a constant distance from the scanners... meaning you get a sphere.
23:22 gaze__ I need to focus on a plane.
23:22 dumbass if you aim the laser right at the center of the mirror which is set on the center of the shaft (grind a flat to inset it), your distance offset is minimal
23:23 furrywolf bah, so I had a good idea, it's just too expensive?
23:23 gaze__ furrywolf: yes
23:23 gaze__ dumbass: I've calculated it. It's too much.
23:24 furrywolf what about a galvo with a parallel linkage? (watts, etc)
23:24 gaze__ fucking slow.
23:25 furrywolf does it need to be faster than the other galvos?
23:25 furrywolf or do you just mean the momentum of the linkage?
23:25 gaze__ ohoh... you mean use a galvo with a parallel linkage to move the lens
23:25 furrywolf yes
23:26 gaze__ that's essentially a voice coil.
23:26 furrywolf all galvos are. but it'd let you use off-the-shelf bits.
23:26 gaze__ ooh... that's a good point.
23:26 gaze__ I really like the idea of a watts linkage
23:27 gaze__ I really, REALLY like the idea of using a watts linkage made out of the voice coil parts from a hard drive :D
23:27 furrywolf or just a slotted arm with a bushing in it, and correct for the sine in software.
23:27 furrywolf since you said it's already on linear bearings.
23:28 furrywolf or a galvo with one of those flex strips from a 5.25" floppy. :)
23:29 gaze__ haha... the thing is... there's already a trig function somewhere in there since I'm correcting for the distance off the center of a sphere
23:29 gaze__ wouldn't it be funny if I could get them to cancel out?
23:29 furrywolf yes, it would. heh.
23:30 furrywolf now, if you were REALLY clever, you'd drive the linkage directly off the two main galvos.
23:30 gaze__ oh man.
23:30 gaze__ that'd be crazy.
23:30 furrywolf you'd need to work out your trig, and see if such a thing could be easily mechanically designed.
23:31 furrywolf I suspect mass would become an issue with such linkages, though.
23:31 furrywolf would need shiny titanium rods or something...
23:31 gaze__ yeah it would. I've designed galvos myself... casted the parts and designed the armature and all that. Inertia is just... first priority for everything
23:32 furrywolf it would, however, be very cute if your focus was purely mechanical...
23:32 gaze__ it would.
23:32 gaze__ but hmm... I'm still curious what the speed of the old hard drive stepper motors is like
23:33 furrywolf fucking slow. 5+ms to move the head a few tracks.
23:33 furrywolf there's a reason they ditched steppers and went to voice coils.
23:33 gaze__ how far apart are the tracks?
23:34 furrywolf very close. heh.
23:34 gaze__ haha that's so bad
23:34 furrywolf there's thousands over the width of the platter
23:34 gaze__ okay... voice coils it is.
23:34 furrywolf stepper hard drives were SLOW.
23:34 gaze__ haha.
23:35 furrywolf the little flex strip out of a 5.25" drive might come in handy for your application, but I don't know what their cycle life is.
23:36 dumbass 116mm to inches?
23:36 gaze__ i'll trust a loop of kynar until it breaks and then etch something better.
23:36 furrywolf You have: 116mm
23:36 furrywolf You want: in
23:36 furrywolf * 4.5669291
23:37 dumbass what's 3" in mm ?
23:37 dumbass 76.2?
23:37 furrywolf You have: 3in
23:37 furrywolf You want: mm
23:37 furrywolf * 76.2
23:42 furrywolf * 76.2
23:42 furrywolf yay, I can do it from within my irc client too. :)
23:46 furrywolf F-Theta Lens 355nm 100mm FL
23:46 furrywolf NT63-312
23:46 furrywolf $2,095.00
23:46 furrywolf I should get into the f-theta lens business.
23:46 furrywolf make crappy moulded ones for hobbyists. :P
23:50 furrywolf why are they so expensive? is the shape difficult to polish? they don't LOOK that hard...
23:50 furrywolf I wonder if you can convince your local eye doctor to have their optics company polish you a couple eyeglass lenses that would do it...
23:51 dumbass multilayered bonded glass?
23:52 furrywolf looks like one of those things that's expensive because it's only sold to big companies, rather than because it's expensive to make.
23:52 dumbass or they wanna make $500/week, and they sell only one per month
23:53 furrywolf I wonder how hard building a cnc lens polisher that can make an arbritary shape is...
23:53 gaze__ hahahaha
23:53 gaze__ they're expensive for good reason...
23:54 gaze__ normal lenses can be made using a blocking body and some pitch and elbow grease
23:54 gaze__ they're spherical
23:54 gaze__ cnc lens grinders use interferometric distance sensing... they need a temperature controlled room
23:54 gaze__ it's insane
23:54 furrywolf depends on the accuracy you need
23:54 furrywolf open loop servo may be just fine for your average home laser scanner
23:55 furrywolf stepper
23:55 gaze__ I mean... honestly for the average hobbyist, the best thing to use is a DLP
23:55 gaze__ and a home theater projector
23:55 gaze__ you know? all the optics you need
23:55 gaze__ works great
23:56 gaze__ err... dlp from a home theater projector
23:56 gaze__ to get structured light
23:56 furrywolf if you're building a big telescope mirror, yes, you need perfect... if you're building a stereolithography machine, you only need the error in the lens to be smaller than the desired precision of the machine...
23:56 gaze__ I want to 3D print tiny gearboxes.
23:56 gaze__ that involute profile had better be awesome.
23:57 gaze__ my machine should have better accuracy than most commercial stereolithography machines since the bed size is so much smaller and the focus will be far tighter than all except some specialty machines
23:57 rrywolf is very, very glad to finally get someone in the channel building something other than re
23:58 gaze__ I'm sick of repraps
23:58 gaze__ honestly
23:58 gaze__ there's much more interesting, available technology out there
23:58 gaze__ printheads are amazing technology for taking something in a computer and making it something physical
23:59 gaze__ the open source community needs to pressure the hell out of a small solvent printhead company to make their control signals available
23:59 gaze__ and then formulate a low viscosity resin and support material
23:59 furrywolf random thought: I think I've seen one-dimension f-theta lenses in laser printers. can you keep your deflection small enough to make one work?