#robotics Logs

Feb 14 2014

00:22 rue_shop3 dosn't that happen every day in russia?
04:23 Jak_o_Shadows Let's redo the torqure requirements for a reprap, because they are clear as mud.
04:55 Jak_o_Shadows Ok. The equations wikipedia has on torque on leadscrews are clearly rubbish, because with a 1kg weight, It's saying it takes 0.011Nm of torque
04:57 Jak_o_Shadows http://www.wolframalpha.com/input/?i=%281*9.81*%288e-3%29%2F2%29*%28%281e-3%29%2Bpi*0.25*%288e-3%29%29%2F%28pi*%288e-3%29-0.25*%281e-3%29%29 Is what i'm doing.
05:00 Jak_o_Shadows However, if this is true, why the heck do you need two big Nema17 motors? ie, a 4500 g.cm stepper is 0.44 Nm
05:00 Jak_o_Shadows and you have two of them!
05:41 shredder_ Any1 competing in DRC?
05:43 Jak_o_Shadows I am currently arguing with myself over the torque requirements for a reprap
05:44 shredder_ Cool ! Mendel?
05:44 Jak_o_Shadows Prusa I suppose.
05:45 shredder_ Why no sla?
05:45 Jak_o_Shadows I am currently upset because the torque requirements seem to be absurdly low compared to what people actually use.
05:45 shredder_ Would save u the stress
05:46 shredder_ U diy?
05:46 Jak_o_Shadows Yeah, eventually
05:47 shredder_ U got BOM?
05:47 Jak_o_Shadows Yeah, sort of. I have yet to double check it.
05:48 shredder_ Under 200?
05:48 Jak_o_Shadows Nope. Probably hardware could be, barely, but the steppers kick it up.
07:20 shredder_ how do barret arms lift heavy loadds?
10:20 GargantuaSauce_ http://www.youtube.com/watch?v=JyG1EeqCmHY
12:09 robotustra GargantuaSauce_ cool
12:09 robotustra not bad
12:09 robotustra but there is a big error
12:10 robotustra need to be corrected
12:13 SlaveToTheSauce i think the error would be reduced a lot by a higher framerate
12:51 GuShH_ rue_house: bah, bad news even though I scraped the surfaces of the pump, sealed it up properly, redid the commutator on the motor, new thrust bearing, etc... it not only began to leak, it also began to smoke, so it's had it. It would need a new set of seals but they're not available anymore, it would probably need a new motor as well. I'm not sure why it smoked, other than water might have leaked into the oil and caused some typ
12:51 GuShH_ e of hydrolock, due to the bad seals.
12:51 GuShH_ so new power washer it is... I was trying to avoid that.
13:08 MrCurious smoking is bad...
13:08 MrCurious get a power washer that can be used as a hydralic cutter
13:12 GuShH_ MrCurious: hm?
13:12 GuShH_ new stuff is shit.
13:13 GuShH_ the outlets on most new karchers are plastic, not aluminum or brass like they used to be.
13:14 GuShH_ now they make you buy an "industrial" model if you want brass.
13:14 GuShH_ it used to be STANDARD on all models.
13:15 GuShH_ and the cheapest ones were all aluminum, nothing plastic.
17:33 dumbass-afk AACKKK
17:34 mbass-afk pats all her fur back down,, it's very un-nerving to see a miyu turn into a hackkitten right in front of
17:35 hackkitten :3
17:36 aveToTheSauce grabs the spray bo
17:36 dumbass-afk <blink>
18:17 robotustra_ evening
18:17 Jak_o_Shadows hi
18:22 robotustra_ how is everything?
18:22 Jak_o_Shadows Ok.
18:23 robotustra_ and robots?
18:23 Jak_o_Shadows Decently busy at the moment.
18:23 Jak_o_Shadows But i'm half-heartedly redoing the torque calculations for a reprap.
18:23 robotustra_ yesterday inserted eyes in the skull
18:24 Jak_o_Shadows nice
18:24 robotustra_ did you see it?
18:24 Jak_o_Shadows I saw the cut-out acrlyic bits
18:25 robotustra_ ok
18:25 robotustra_ https://www.youtube.com/watch?v=_HABjn7qLSY
18:25 robotustra_ I call it R.E.M. = random eyes movements
18:26 robotustra_ now have to make syncronization
18:27 robotustra_ thinking about algorythms
18:27 Jak_o_Shadows Cool.
18:27 Jak_o_Shadows You should be able to use both eyes to get the depth of objects, eventually?
18:27 robotustra_ that's the goal
18:27 robotustra_ 3D map
18:28 robotustra_ of objects
18:28 Jak_o_Shadows cool
18:29 robotustra_ and calculate the position of the head real time with respect to the room
19:46 Jak_o_Shadows Right, so apparently all my ultrasonic sensors are buggered
19:49 robotustra_ how come?
19:50 Jak_o_Shadows They are not working
19:50 Jak_o_Shadows Or, I had 2 wires around the wrong way.
19:50 Jak_o_Shadows damn i'm good
19:51 robotustra_ soldered wires coprrectly?
19:51 Jak_o_Shadows Yeah. This is just on a breadboard though
19:52 robotustra_ an ugly breadboard with 2 stange cylinders on it?
19:53 robotustra_ with the grid on them?
19:55 Jak_o_Shadows 'bwah? Now to double check that the msp430 is doing the right thing.
22:24 peepsalot hello, anyone here familiar with pneumatics? i got this solenoid block for free but have no idea how it works http://i.imgur.com/GsLWPuw.jpg
22:24 Jak_o_Shadows OOoh, fancy
22:26 peepsalot the solenoids are labeled 12V 1.8W, which is fine. both ports seem to flow into the main block no matter if i power one or the other side of the solenoid
22:27 dumbass-afk should alternate which is pressure and which is return
22:28 dumbass-afk it's plainly for double-acting cylinders, would be a hoot if it was proportional too
22:29 Jak_o_Shadows I'd agree with dumbass-afk
22:29 peepsalot i want to try to use this for artificial muscles
22:30 peepsalot right now i'm just blowing through a tube to try to understand
22:30 dumbass-afk <cough>
22:31 Jak_o_Shadows You'll have fun with routing the tubes
22:31 peepsalot so where does the return go? out this port with a filter lookin thing on it?
22:32 dumbass-afk yeas
22:32 peepsalot i tried covering it but both ports still seem to flow
22:33 peepsalot oh its going out the other returns
22:33 dumbass-afk sometimes valves need pressure to push the seals shut, or maybe you got it free because it's clogged open
22:33 peepsalot this is a pain to only test one, i gotta block off all the others
22:33 mbass-afk sighs.... get some real air pressure to test it
22:34 peepsalot i need fittings
22:36 peepsalot not even sure how i'll hook this to air compressor
22:36 mbass-afk pokes hackkitten ; look ! a peepsal
22:37 peepsalot dumbass-afk, what did you mean about it being proportional?
22:37 peepsalot i need a crash course in pneumatics
22:38 dumbass-afk by allmeans, coming to irc to get made fun of for not looking thru DDG first, well, umm, mevermind
22:38 Jak_o_Shadows proportional could possibly mean that you can have control over the position of the piston, rather than just extended/retracted?
22:39 dumbass-afk yeas
22:41 dumbass-afk https://duckduckgo.com/?q=pneumatic+valve+proportional
22:43 dumbass-afk so you can ease a piston down the cylinder, instead of applying full air pressure all at once
22:43 dumbass-afk by trottleing the end of stroke in high pressure fast hydraulics, the system lasts longer, because it's not slamming from end to end
22:44 Jak_o_Shadows I thought that a number of pistons had little vent things to stop that?
22:45 dumbass-afk in single acting cylinders, sure
22:45 dumbass-afk peepsalot has double acting valves
22:45 armyofevilrobots proportional control of a pneumatic piston is pretty easy. Esp. if you have a dual acting cylinder AND a position sensor. Just PID to control the ratio of the two sides. It's like locked antiphase on a motor controller.
22:46 peepsalot they are 2 position, 4 way, baed on part # but i coudln't find a datasheet
22:46 armyofevilrobots the only trick is a lot of the solenoids have limited lifespans when you PWM them.
22:46 dumbass-afk in some steam engines, the relieve exhaust would be closed before the piston reached the end of stroke to provide a cushion of brakeing air
22:47 GargantuaSauce attn rue_bed rue_house
22:47 dumbass-afk peepsalot , there's prolly 5 or 6 parts numbers on that hunk, each for a different part of it
22:47 dumbass-afk look them all up
22:47 peepsalot all of the solenoids are the same, numatics M10SS400M
22:48 peepsalot oh, i can hear balls rattling around when i tip it, does it need ot be a specific orientation?
22:49 dumbass-afk Part Number: M10SS400M Make: NUMATICS Description: SOLENOID VALVE 24VDC 13-32NPT 2POSITION 4WAY etc
22:49 dumbass-afk the balls are prolly loose because it's been used and the springs are weak and it needs air pressure to set and hold them in place
22:49 dumbass-afk Numatics MicroAir M10SS400M 24VDC 18 Watts Air Valve $41.95:
22:50 peepsalot also its strange that all the search results say 24V when the parts i have are clearly labeled 12V. do they count it as 24V since there's two solenoid jacks?
22:52 dumbass-afk about the only people who would know that are those that have one, and i bet you are the only one in here with one
22:52 mbass-afk hands peepsalot the internet to seach thru , there's 1000's of hits on https://duckduckgo.com/?q=numatics+%22M10SS400M%22
22:52 dumbass-afk (if you count the google link at the bottom)
22:54 armyofevilrobots Seriously look for the cycles to failure on those. A lot of those valves die after 10k actuations or so, which happens awful fast if you are trying to do proportional control.
22:55 myofevilrobots had some mac valves that had 10k cycles/failure. Died in _hou
22:55 dumbass-afk "lapped spool and sleeve assembly" <<== gets leaky with fairly low number of cycles
22:56 peepsalot dumbass-afk, i did search the part# before asking in here, and none of the results gave me much useful information. sometimes its nice to discuss with other humans
22:56 dumbass-afk i agree, but we are a very limited resourse against the millions of parts out there
22:57 dumbass-afk just letting you know
22:58 dumbass-afk since it is air-rated, and is prolly leaky as heck, you *might* get better performance from it if you can run oil thru it instead of air
22:59 dumbass-afk you can get a 35psi liquid pump 12vdc off ebay for $20 or so
23:00 dumbass-afk 35psi in a 4" pvc cylinder will push 400lbs, enough to pick up , and crush, a coke can
23:01 dumbass-afk ask someone with a lathe to spin you off some pistons for pvc water pipe
23:02 peepsalot dumbass-afk, i plan on trying this sort of thing rather than pistons: http://www.youtube.com/watch?v=AkaVsoEd6Vo
23:02 dumbass-afk ok
23:02 GargantuaSauce definitely talk about this with rue when he's around
23:03 dumbass-afk rue made a nice one with an avr controlling it
23:03 GargantuaSauce he's done an air muscle servo
23:43 Jak_o_Shadows for petes sake inventor.
23:43 Jak_o_Shadows oh good, you didn't crash
23:50 Jak_o_Shadows For the reprap y-axis: Why the whole 2 small threaded rods, lots of nuts, and 3 printed bits? (on each side). Why not make that out of a solid piece of material, and just embed the bearings into it, and use a small bracket for the motor mount/idler?
23:50 Jak_o_Shadows Reprap people seem to overly like threaded rod
23:54 peepsalot still trying to understand this diagram http://i.imgur.com/HYRG8OF.png
23:54 peepsalot i'm pretty sure thats the one for my valves
23:54 Jak_o_Shadows Oh, I got this.
23:55 Jak_o_Shadows I don't however know what part is confusing you
23:58 peepsalot what are the weird notches on the top right
23:58 Jak_o_Shadows Bugger if I know.