#robotics Logs

Mar 14 2014

00:18 rue_more 10pm having an advil
00:51 rue_more not burning supper tonight, didn't turn the stove on!
05:04 rue_house aah I have two different things going on here at the same time
05:05 rue_house I have reflux making my throat raw
05:05 rue_house and a virus attacking it
06:05 zap0 stop all dairy food now. start on citrus.
07:07 rue_more the citris is causing my stomach to react tho
10:07 MrCurious a life without cause is a life without effect
10:58 rue_more I think stress reflux got me here in the first place
11:02 armyofevilrobots hahaha, sometimes that fire burning inside us isn't a passion for technology.
11:03 armyofevilrobots Srsly though, my wife is crazy sick still, and it was like a flu and food poisoning all wrapped up in one.
11:03 armyofevilrobots I have totally avoided it (go flu-shot)!
11:07 rue_more maybe next year I'll try a shot
12:05 rue_more thnaks to the new Gimp, I dont save anymore, I export everything
12:17 rue_more the hell with it, I'm taking an advil
12:19 SlaveToTheSauce you goddamn junkie
13:07 GuShH_ dang it
13:07 GuShH_ they gave me the wrong ring size for the chainsaw!
13:07 GuShH_ and I handed them the piston with the ring so they would measure it, plus I told them the size
13:08 GuShH_ you gotta double check everything don't you, people are useless.
13:24 armyofevilrobots You just figured this out now?
13:42 rue_more 11:20 had advil
14:26 f00bar80 is there a way to build a robot's gripper from meccano without using servos but without gears, as i'm actually lacked of any gears
14:27 rue_more cables
14:27 rue_more cables are wonderfull things
14:29 f00bar80 rue_more, how ??? can you show me a sample ?
14:29 SlaveToTheSauce well you still need SOMETHING for actuation
14:29 SlaveToTheSauce and a bare meccano motor with no torque converter won't do
14:30 f00bar80 SlaveToTheSauce, no i'm using servos
14:31 SlaveToTheSauce well your question implied the opposite
14:31 f00bar80 SlaveToTheSauce, sorry typp
14:31 f00bar80 typo*
14:32 f00bar80 so how can i build a gripper with meccano/servos/cables
14:32 SlaveToTheSauce you should be able to actuate a lever directly from the servo spline then, or yeah stick a cable on the end of a servo horn and use that to pull on the 'fingers'
14:33 f00bar80 anybody can show me a sample , i can't visualize it
14:33 SlaveToTheSauce for connecting a meccano beam to a servo use an m3 bolt and a toothed washer
14:33 robopal just google images :D
14:34 SlaveToTheSauce http://workman-industries.net/images/hexapod/hexapencil.jpg this shows it a bit i guess
14:35 SlaveToTheSauce obviously a gripper is going to need two opposing levers and a grippy edge, perhaps on a pivot
14:35 SlaveToTheSauce i don't really like meccano for robotics but that is mostly because i don't have a huge variety of pieces i guess
14:35 SlaveToTheSauce never really figured out how to make decent useful structures out of it
14:35 robopal i like the idea where the gripper is normaly closed held with a strong spring, and you pull a string when you want to grab something and then it is held with mechanical force (spring) not electrical
14:36 robopal (I mean by pulling the string, opens the grip)
14:36 SlaveToTheSauce https://www.youtube.com/watch?v=bj9gFFyR3-Y and here's the above walking
14:36 SlaveToTheSauce i've since replaced the whole mechanical structure
14:36 f00bar80 SlaveToTheSauce, where are the cables here
14:37 SlaveToTheSauce no cables, the meccano beams are directly bolted to the servo splines
14:37 f00bar80 SlaveToTheSauce, so how i can get built with cables then ?
14:38 SlaveToTheSauce look at your hands
14:38 SlaveToTheSauce the muscles are all in your forearms
14:39 SlaveToTheSauce tendons run through your wrists up to your fingers to actuate them
14:39 robopal get a chicken leg and pull the veins :D
14:40 SlaveToTheSauce http://www.youtube.com/watch?v=ONPkB-TmphE
14:40 SlaveToTheSauce there are lots of designs like this
14:40 SlaveToTheSauce using meccano will add constraints to the design but i imagine it's doable
14:43 f00bar80 SlaveToTheSauce, just i'm looking to build simple one like this http://store.fut-electronics.com/ROB-grip-1.html
14:43 SlaveToTheSauce well that has a pretty straightforward mechanism to implement in mecanno for sure
14:44 SlaveToTheSauce just replace the gears with a pair of servos
14:44 SlaveToTheSauce drive the levers directly like i do
14:48 SlaveToTheSauce the hard part might be fixing the servos to the structure, but i'm sure you'll be able to come up with something
14:48 SlaveToTheSauce hot glue is always an option
14:59 f00bar80 SlaveToTheSauce, this is a starting i think http://www.robotscience.co.za/how_to/meccanoskippy/007_L.jpg
15:00 SlaveToTheSauce is that a stock part? huh
15:00 SlaveToTheSauce i dont have any that are narrow like that
15:00 SlaveToTheSauce guess you could mill away an edge anyway
15:01 SlaveToTheSauce (but if you're going to be machining why use meccano in the first place)
15:01 f00bar80 SlaveToTheSauce, the cheapest option i got
15:03 f00bar80 SlaveToTheSauce, what other options you suggest ? LEGO are too expensive when it comes to technic
15:04 SlaveToTheSauce well i've tried 3d printing with not a huge amount of success. it's hard to design stuff for extrusion, or at least too hard for my level of competence. going to give it another shot though
15:05 SlaveToTheSauce i think byfar the best option is to machine your own stuff out of aluminium but obviously that requires tooling and skill
15:05 SlaveToTheSauce both of which i lack
15:05 f00bar80 SlaveToTheSauce, do you think this also is narrow http://diydata.files.wordpress.com/2008/08/armleftside.jpg , or it's mounted/fixed in different way?
15:06 SlaveToTheSauce i think the mounting tabs on those servos are further out than most
15:06 SlaveToTheSauce not sure though
15:07 SlaveToTheSauce in any case as i said all you need is an edge of the servo to be resting against the frame, and then you can go to town with hotglue or something
15:07 SlaveToTheSauce also note the cable tie. i've made good use of those also
15:08 SlaveToTheSauce basically as long as you're not designing the parts from scratch, you're going to be making some 'hacks' to make it all fit together
15:08 SlaveToTheSauce since those servos and meccano are not designed to get along
15:08 f00bar80 you mean between the servo's horn and the beam ?
15:08 SlaveToTheSauce no, that can be done with a bolt as in my hexapod imae
15:08 SlaveToTheSauce image
15:09 SlaveToTheSauce i just mean from the body of the servo to the frame
15:09 SlaveToTheSauce don't use a horn, just get m3 bolts and toothed washers
15:11 SlaveToTheSauce though i guess gluing a beam to a horn might work too, dunno
15:11 SlaveToTheSauce may be worth trying
15:11 SlaveToTheSauce still use an m3 bolt to secure it though
15:12 f00bar80 any cheap kit you know of for both the bolts / toothed washers ?
15:12 SlaveToTheSauce generally 'kits' have a very high markup compared to their contents purchased individually
15:13 f00bar80 SlaveToTheSauce, where or what do i search for in amazon for example
15:13 SlaveToTheSauce m3 bolt or m3 cap screw
15:14 SlaveToTheSauce http://stores.ebay.ca/northern-supply-2012/M3-/_i.html?_fsub=4381228013&_sid=47398643&_trksid=p4634.c0.m322 this is the guy i use for fasteners
15:14 f00bar80 and the toothed washers?
15:15 SlaveToTheSauce hmm i guess i got mine elsewhere
15:15 SlaveToTheSauce yeah bought those retail at fastenal....you'll want to get them all from one place i suppose
15:16 SlaveToTheSauce http://www.ebay.ca/itm/Stainless-Steel-A2-Metric-Lock-Washer-M3-100-Pack-/171210695962?pt=LH_DefaultDomain_2&hash=item27dcf3e51a
15:16 SlaveToTheSauce these *might* work instead of toothed washers but i'm not sure
15:16 SlaveToTheSauce you won't need toothed washers if you're gluing it to the servo horn i guess
15:16 SlaveToTheSauce just bolts
15:17 SlaveToTheSauce oh you're not in north america so that supplier won't work anyway
15:19 f00bar80 SlaveToTheSauce, sorry but what differs a m3 bolt from a normal meccano's screw ?
15:19 SlaveToTheSauce m3 bolts are 3mm wide and have .5mm pitch i think
15:19 SlaveToTheSauce meccano screws are 1/8" i believe?
15:20 SlaveToTheSauce and the servo spline hole is 3mm
15:22 f00bar80 SlaveToTheSauce, but still the meccano's beam hall is wide i think
15:22 SlaveToTheSauce yes it is, that's why i used toothed washers
15:23 SlaveToTheSauce if you are using the servo horn and gluing it to the beam that will transmit the torque just fine
15:23 SlaveToTheSauce just want the bolt through there to hold the horn and beam on the spline
15:24 f00bar80 SlaveToTheSauce, i want to ask :) ,, how i can make connected beams loose but not fully free with the meccano's screws ?
15:25 SlaveToTheSauce i never quite figured that out
15:25 SlaveToTheSauce if you put two nuts on you can tighten them against each other
15:25 SlaveToTheSauce but it is hard to get it just right
15:31 f00bar80 SlaveToTheSauce, how to put 2 nuts on, in which way you mean ? something like this http://thumbs3.ebaystatic.com/d/l225/m/mq3pBFqo7GIuFkrlhLjM15w.jpg
15:31 SlaveToTheSauce you'll need to use one of the screws with threads all the way up
15:32 SlaveToTheSauce so it'll go screw cap, beam, beam, nut, nut
15:32 SlaveToTheSauce so that the nuts aren't tightened against the beams but they are against each other
15:32 SlaveToTheSauce you could put a spacer between the beams if you want
15:33 f00bar80 SlaveToTheSauce, can you show me how .. :) sorry .. can't recognize it
15:33 SlaveToTheSauce i am not at home so i can't
15:33 robopal or use a locking nut
15:34 SlaveToTheSauce i don't think mecanno has those
15:34 robopal why use mecano screws/nuts?
15:34 SlaveToTheSauce because they fit the meccano holes
15:35 robopal i am sure he can find more options in the hardware store
15:35 SlaveToTheSauce yeah
15:36 robopal improvise
15:36 SlaveToTheSauce by all means
15:40 robopal http://www.rockler.com/wordpress/wp-content/uploads/2012/12/Jamb-Nuts-and-Washers.jpg
15:40 robopal jam nuts hehe, I didn't remember that term
15:40 SlaveToTheSauce yeah i forgot it too
15:43 f00bar80 SlaveToTheSauce, http://www.robosoftsystems.co.in/roboshop/media/catalog/product/pdf/Meccano_Gripper.pdf , on page 32 4 are used , does it really can make any difference ?
15:44 SlaveToTheSauce well in that design they want a space between the two beams
15:46 f00bar80 SlaveToTheSauce, what are called those gears type?
15:47 SlaveToTheSauce worm gear in the middle, spur gears on the fingers
15:47 SlaveToTheSauce you don't need gears at all if you use a separate servo for each of the two fingers
15:48 SlaveToTheSauce (you'll want to command them to move in unison in software of course)
15:50 f00bar80 SlaveToTheSauce, i mean with multiple holes
15:50 SlaveToTheSauce they're still spur gears
15:50 SlaveToTheSauce they just happen to be big
15:51 SlaveToTheSauce and full of holes
17:38 GuShh_Lap2 rue_more: feeling better?
17:39 GuShh_Lap2 bah ring size is too big... no wonder, the clerks were talking about dildos when I arrived, I kid you not.
17:56 SlaveToTheSauce http://www.youtube.com/watch?v=m9uoJyyoVyk
21:10 GuShH_ rue_house: math tells me I would need over 80.000RPM if I wanted to drill stainless with these micro hss bits without them breaking apart in the first try, better go with EDM.
21:11 GuShH_ been reading model making forums, they do a lot of tiny hole drilling
21:18 rue_mohr2 duh no
21:18 rue_mohr2 thats why I said use 500rpm, under water and put under some pressure to let it just slowly cut thru
21:26 GuShH_ rue_mohr2: nah
21:26 GuShH_ stainless would harden instantly
21:27 GuShH_ it needs an agressive entry
21:27 GuShH_ ie full feed from the get go
21:30 rue_mohr2 the speed dosn't matter, its the cut rate
21:30 rue_mohr2 you can make the same cut at 500rpm that you can make at 30k
21:31 rue_mohr2 GuShH_, your gonna conclude its impossable for you to drill it
21:36 rue_mohr2 if my reactor is low on hydrochloic acid, can I substitute acetic acid?
21:44 Tom_itx rue, not so sure about that
21:44 Tom_itx i understand chip loads and rpm
21:44 Tom_itx ss work hardens easy
21:45 Tom_itx that small bit won't take much stress
21:46 Tom_itx it's probably what took prusa so long to get his nozzles out there
21:46 Tom_itx if he even has... dunno, i left the channel
21:48 rue_mohr2 you did?
21:48 Tom_itx ages ago
22:14 myofevilrobots so wants an EDM machine too. Maybe after the powderbed printe
22:27 GargantuaSauce http://www.youtube.com/watch?v=ewKpyZfNuEU this is interesting
22:33 armyofevilrobots That's effing cool
22:33 armyofevilrobots closed loop simulation->fabrication
22:34 GargantuaSauce and that's the prelude, the dead end
22:34 armyofevilrobots haha. I am only 15 mins in.
22:34 armyofevilrobots I skipped the endless intro sequence.
22:58 Duzz cool
23:02 armyofevilrobots This is a crazy presentation; we found the holy grail, but it didn't come with a manual. Way too good to be true.
23:03 GargantuaSauce they commercialized it
23:03 myofevilrobots fires up his day-trading accoun
23:03 GargantuaSauce http://www.nutonian.com/
23:04 GargantuaSauce wish it was ofss
23:05 GargantuaSauce foss*
23:33 MrCurious grocery store has sacks of potatos on sale 2 for 1 for st patricks day
23:33 MrCurious isnt that like having watermelon on sale 2 for 1 on MLK day?
23:34 MrCurious yet there is no outrage!
23:34 GargantuaSauce this is white privilege
23:34 MrCurious snap. spot on
23:34 MrCurious unless you haev seen the movie blazin saddles
23:34 GargantuaSauce i haven't, but keep meaning to
23:34 MrCurious we will take the ____ers and we will take the __nks, but we wont take the irish!
23:35 GargantuaSauce sounds about right