#robotics Logs

Aug 08 2015

01:45 veverak what is life?
05:46 deshipu_ na na nana na
05:52 password2 catwoman
06:56 deshipu I suck at laser-cutting: https://hackaday.io/project/6608-talk-ranking-machine/log/22313-laser-cutting
08:37 deshipu rue_house: http://letsmakerobots.com/robot/project/the-monster-budget-robot-arm
08:48 SpeedEvil deshipu: I was a couple of days ago considering a brute force solution to my gardening issues.
08:48 SpeedEvil deshipu: Involving an arm on a centre-piviot in my garden, with a 20m boom.
08:52 deshipu duck!
08:52 SpeedEvil Trusses are fun
08:52 deshipu why not an army of spider robots? :D
10:44 blockh34d hi
10:45 blockh34d i'm doing some diy homebrew cnc stuff lately, using a lot of conduit
10:45 blockh34d it makes me wonder how much of a hexapod someone could make with this stuff
10:45 blockh34d anyone know of any interesting conduit based hexapod or maybe chicken walker style FOSS plans?
12:03 rue_house thats a LOT of plastic
12:05 rue_house all cantilevered... sigh
12:51 JEntrep hey everyone :)
13:11 deshipu blockh34d: conduit?
13:26 blockh34d deshipu: its a steel tubing used in america for electrical wiring in homes and such
13:26 Tom_itx see if that helps
13:26 blockh34d i'm finding that the 3/4" ID variety is remarkably rigid and strong
13:26 blockh34d so i thought maybe the legs of a hexapod could be mostly this tubing
13:31 deshipu too heavy
13:31 deshipu you really want it all to be as light as possible
13:31 deshipu inertia is your enemy
13:32 blockh34d what about small fiberglass rods? three of them mounted in a rigid triangle to reduce flexation
13:33 blockh34d maybe a few fittings every so often along the length to conform to the triangle shape
13:33 blockh34d thats pretty light and strong as hell
13:34 blockh34d i'm talking about those orange rods people use to mark the edge of their driveway btw
13:34 blockh34d they're about 1cm thick or so, probably closer to 8mm
13:34 blockh34d crazy strong, you could make a nice bow with a few of them for example
13:36 deshipu well, it depends what you are making, really
13:36 deshipu at the sizes I work, the plastic horns that you get with the servos are quite enough
13:37 blockh34d i want to make something fairly large i think
13:41 deshipu larger is harder
13:42 deshipu maybe try with a small one first, and once you get that to work, go larger
13:46 blockh34d yeah thats a good approach deshipu i will probably do that
13:46 blockh34d i like some of the reprap 3d printer designs the way they're setup for scalability
13:47 blockh34d i may try to emulate that with some of the dimensions of a walker, particularly the legs
13:50 deshipu there was a 3d-printed spider robot with parametric opescad design files...
13:50 deshipu let me find it
13:50 blockh34d oh cool thanks
13:50 deshipu https://www.youtube.com/watch?v=7McQQ-uikZw
13:51 deshipu oh, they are now selling it, cool
13:51 deshipu http://metabot.cc/
13:51 deshipu it was called "spidey" back when I saw it
13:51 blockh34d interesting, thanks for the link
14:16 wolfmanjm eh they use very expensive servos.. $21 per servo!!! I prefer the $2/servo or less like stubby uses
14:16 wolfmanjm although there are problems with low torque :) but I have overcome most of them so far
14:16 SpeedEvil yes, because they are exactly the same, and $2 servos don't fall apart if you look at them
14:17 wolfmanjm no the $21 servo are great if yo ucan afford 18x$21 or $378 just for the servos
14:18 SpeedEvil True.
14:19 wolfmanjm I'm using the MG90S they do not fall apart they have metal gears too. They are just a tad wimpy in torque though
14:19 SpeedEvil But a $36 pile of servos that buzzes twice and all the legs fall off isn't much better
14:19 wolfmanjm however with some clever programming I think I have overcome the torque issue :)
14:20 wolfmanjm but if I had failed I would redo it using the 4 linkage system that stubby used to increase the torque
14:21 wolfmanjm I've figured out the IK for that in case I had to go that route. it turned out to be not that hard if you understand complex numbers :)
14:21 wolfmanjm (which I don;t)
14:22 wolfmanjm but I can code equations
14:23 SpeedEvil :)
14:24 wolfmanjm heh another thing they call 'Open Source" but is CC BY-NC which technically is NOT open source!
14:24 blockh34d i've been wondering if i should jsut use steppers for everything
14:24 blockh34d it'd be sloewr but stronger, right?
14:24 wolfmanjm too heavy
14:24 wolfmanjm 18 steppers would weigh a ton
14:24 blockh34d ah yeah they're little b ricks
14:25 blockh34d what if it was basically one big ass stepper, and 18 spindles could selectively push themselves into the main drive like a bunch of worm gears spaced a little off a giant central worm gear, unless a solenoid is hit to push it in
14:25 blockh34d if that makes any sense
14:26 wolfmanjm I think maybe regular motors with servo control would be cheaper in this case, and you can get pretty torquy motors that are still quite small especially when geared down
14:26 blockh34d so you could run multiple off one motor source at a time, although they would all have to be moving the same direction, unless that could be factored in somehow
14:26 blockh34d ah k
14:27 blockh34d i'm building a little cnc to test out my smoothie mods locally btw
14:27 wolfmanjm there are plenty of walker designs that use very motors, yu don; thave to have 3 DoF per leg
14:27 blockh34d for the 4th and 5th axis i thought i'd make a way to move the entire sheet its cutting from underneath
14:27 blockh34d so its maybe 4ft by 2ft, but then the 4th/5th axis could slide an 8x4' sheet back and forth around under that
14:28 blockh34d i'll probably just cut foam with it
14:33 wolfmanjm the 4th axis is generally rotary on CNC
14:41 blockh34d i see... that'd be nice too. i thought i might go with one stepper that rolls a sheet of material foward back, and another very similar that rolls a conveyor along, so i could mprogress between prints automatically. this cnc can be fit with an extruder so i will probably do that too, since theres very little sideload
14:42 blockh34d i'm not sure how much precision i can expect from conduit rails. my guess is 'none' to 'laughable', but who knows, this projects demo videos look promising.
14:58 rue_shop3 what are you using them for?
14:58 rue_shop3 cnc?
14:59 theBear i doubt it's for a train :)
15:14 blockh34d rue_shop3: yeah a mostly printed cnc project i found on thingiverse, looks kinda neat
15:15 blockh34d item # 724999
15:15 blockh34d www.thingiverse.com/thing:724999
15:20 blockh34d uses a ridiculous number of bearings
15:24 rue_shop3 waaaaaaaaaaaaaaaaaaay too much plastic
15:24 blockh34d yeah i redid the corners with much less plastic
15:24 blockh34d using manufactured 90 degree elbows mounted on a plate
15:24 blockh34d unfortunately that plate is still plastic, for now,but soon may be metal as i phase all plastic out of the frame
15:25 rue_shop3 but its a good design
15:25 blockh34d yeah i like it
15:25 blockh34d i hope to mill little pcbs with it
15:25 blockh34d cut some foam, that kinda lightweight stuff
15:25 blockh34d sec i have pic of my z so far
15:26 rue_shop3 do you know what size pipe he used?
15:26 rue_shop3 1/2" or 3/4"
15:26 blockh34d 3/4" ID
15:26 blockh34d thats about 0.93" OD iirc
15:26 rue_shop3 hah it'l be 3/4" trade
15:26 rue_shop3 the trade sizes have nothing to do with the pipe size
15:26 blockh34d oh hah
15:26 blockh34d hows that work?
15:26 rue_shop3 nobody knows
15:27 blockh34d is it like how 2x4's aren't actually 2 by 4?
15:27 rue_shop3 I have a chart
15:27 rue_shop3 http://ruemohr.org/~ircjunk/tutorials/mech/EMTchart.html
15:27 blockh34d ah thanks
15:27 rue_shop3 all the pipes I could find to measure
15:27 blockh34d how big do you think i could make that thing?
15:27 blockh34d with some stepped up steppers that is
15:28 rue_shop3 not much load, prolly about 36"
15:28 blockh34d cool
15:28 blockh34d do you think i should fill the conduit with epoxy or something like that? maybe epoxy granite?
15:28 rue_shop3 this buy put a crazy amount of work into this
15:28 blockh34d seems like it
15:29 rue_shop3 http://www.thingiverse.com/make:151998
15:29 blockh34d the z: http://s21.postimg.org/ywymbddx3/WP_20150805_15_06_29_Pro.jpg
15:29 SpeedEvil Scaffolding tube is way more rigid than conduit
15:30 rue_shop3 its the right amount of bearings
15:30 blockh34d lol thingiverse has a funny 404
15:31 rue_shop3 hah, thats good
15:32 blockh34d thats an interesting way that make has mounted teh cnc
15:32 blockh34d i was wondering about using cables kinda like that, but i thought it'd be cool to use the truck tie downs you can torq down
15:32 blockh34d then the whole thing could be ratcheted into super snug
15:33 blockh34d i think my corner pieces look cooler than that
15:33 blockh34d but i'm not sure if they're legit
15:34 blockh34d looks like the whole thing folds up into his wall
15:34 blockh34d that's really smart
15:34 rue_shop3 I wonder if those peices are too complex to cast in aluminum
15:34 blockh34d i dunno they have some weird stuff going on with nut pockets
15:35 blockh34d my reworked corners use cast aluminum fittings
15:35 blockh34d but i'm using hardware store stuff
15:35 blockh34d to make it more precise i tapped two more holes around the edge and use two more machine screws to apply pressure at 3 points around the tube instead of just one
15:35 blockh34d that way i can get a real 90 degree thing going on
15:36 blockh34d i made a small scale test and it seems pretty true so far, the double diagonal test has it within a millimeter with all corners showing 90 and no wiggle or play in it at all
15:37 blockh34d you should make one, seems like it could almost be made with random spare parts
15:37 blockh34d i used a bunch of scrap rollerblades for bearings
18:19 Tom_itx dunno how to get them, they're coming in on random ip's
18:36 rue_house whats comming in?
18:37 Tom_itx if you could see join part you would know
18:37 rue_house well, there is a reason I ignore joins and parts
18:38 Tom_itx as an op you are somewhat obligated not to
18:38 rue_house just a sec
18:38 Tom_itx no clue how to fix it though other than asking freenode
18:39 rue_house http://paste.debian.net/290442/
18:39 rue_house look over that list and tell me if the ip's seem to match
18:40 Tom_itx 105.158.13.203 is the most recent
18:41 rue_house its probably ruccas you know
18:41 rue_house filter 105.158.*
18:41 rue_house the whole isp
18:42 rue_house inetnum: 105.158.0.0 - 105.158.255.255
18:43 Tom_itx ~Eurpu@ber19-3-78-220-252-108.fbx.proxad.net
18:43 rue_house ipv6
18:44 Tom_itx ~oiri@cac94-8-82-245-27-76.fbx.proxad.net
18:44 rue_house yea, I'd say its ruccas, you know how big hit botnet is?
18:44 rue_house yea, I'd say its ruccas, you know how big his botnet is?
18:45 Tom_itx ~Pcfav@ber19-3-78-220-252-108.fbx.proxad.net
18:45 rue_house ipv6
18:46 Tom_itx ~vnsee@ber19-3-78-220-252-108.fbx.proxad.net
18:46 rue_house filter the ip 108.252.220.78.3.19
18:47 rue_house no I'm good thanks
18:48 Tom_itx ~eixu@cac94-8-82-245-27-76.fbx.proxad.net
18:48 rue_house ok, filter 76.27.245.82.*
18:48 rue_house dont need anyone who is ipv6 anyhow
18:49 Tom_itx ~eouq@cac94-8-82-245-27-76.fbx.proxad.net
18:49 rue_house yup, that filter would work on that too
18:50 rue_house he prolly has just a few hosts on the two networks
18:50 rue_house I dont have any ipv6 turned on here at home, so I cant help
18:50 Tom_itx i don't think i do either
18:51 Tom_itx that seemed to slow it down a bi
18:51 Tom_itx ~ocaow@cac94-8-82-245-27-76.fbx.proxad.net
21:54 robotustra hi ppl