#robotics Logs

Nov 28 2013

00:26 MrCurious d
13:18 MrCurious GuShH: you around?
13:59 GuShH MrCurious: no
13:59 GuShH MrCurious: are you?
15:20 MrCurious apparently not
16:27 MrCurious make more robots....
17:49 R0b0t1 MrCurious: Make me a robotic steed
17:50 MrCurious dont call me steed
17:51 MrCurious and whats with steed? srsly, is this 1800's should i call your Moriarty
17:52 MrCurious dont be afraid. i just sound mean...
17:54 Tom_itx grouch
17:55 MrCurious sir, i cannot argue with that perfecctly accurate accessment
17:56 MrCurious i got out bid on some timing belt and ullys on ebay
17:56 Tom_itx well that's enough to piss off a preacher
18:02 MrCurious pondering putting a second gantry on te cnc machine
18:02 MrCurious 1 gantry for cnc cutting, one for extruding
18:12 Tom_itx probably not heavy enough is it?
18:12 Tom_itx cutting what?
18:17 MrCurious nah, 1 gantry is enough
18:17 MrCurious hopefully everything up to mild steel
18:18 Tom_itx not if it's currently a reprap
18:18 MrCurious its not
18:18 Tom_itx phew!
18:18 MrCurious its very heavy
18:18 MrCurious over engineered i suspect
18:19 Jak_o_Shadows I think I should design an awesome 9 monitor mount
18:19 MrCurious do you have 9 monitors?
18:19 Jak_o_Shadows Noooo, but I want 9 monitors
18:20 MrCurious go for it :)
18:21 Jak_o_Shadows I'm thinking a sort of frame, with adjustable mounts and such.
18:22 Jak_o_Shadows I could probably design and make the frame, the joints would be a little hard.
18:22 MrCurious machine aint gonna finish itself. time to get to it
18:23 Tom_itx well i'm wiring my cnc atm too
18:46 MrCurious Tom_itx: pix ofyour cnc?
18:48 Tom_itx http://tom-itx.dyndns.org:81/~webpage/sherline_files/sherline_index.php
18:48 Tom_itx old
18:48 Tom_itx http://tom-itx.dyndns.org:81/~webpage/cnc/psu/psu_index.php
18:48 Tom_itx new psu & drivers
18:50 Tom_itx adding some test IO boards to it
18:51 robotustra club of cnc lovers
18:55 MrCurious sherline style?
18:55 Tom_itx yes
19:16 MrCurious so a 4"x2"x2" work envelope?
19:19 Tom_itx 7 x 9 x ?
19:20 Tom_itx 8 x 7 x 6 approx
19:20 MrCurious small
19:20 Tom_itx i know
19:20 MrCurious you should use it to make a bigger one :)
19:20 Tom_itx i've run the big ones too
19:21 MrCurious god knows you would finish before me
19:21 Tom_itx ie 1/2 mil dollar ones
19:21 MrCurious given mine is 3+ years in the making
19:21 Tom_itx i've had it for years
19:21 Tom_itx made improvements along the way
19:29 ua_ if i have a regular motor and it cant move will it break at some point?
19:29 ua_ i mean something is blocking axis from movement
19:29 Jak_o_Shadows So you're stalling the motor.
19:30 Triffid_Hunter ua_: most motors will burn out
19:30 Triffid_Hunter ua_: some motors, such as trolling motors and stepper motors will not
19:31 ua_ ok, thanks :)
20:00 GargantuaSauce Jak_o_Shadows: have yo played mass effect 3?
20:01 Fiesta is that a FPS game?
20:01 Jak_o_Shadows Nope.
20:03 GargantuaSauce i cant find videos of it working properly, only a bug but http://www.youtube.com/watch?v=u3EuMh5380w
20:03 GargantuaSauce they're supposed to all just point at you
20:07 Jak_o_Shadows ah, ha
20:26 ua_ are there open source designs of small humanoids like aldebaran nao?
20:28 ua_ aldebaran nao costs $16k for best version, they are fucking crazy if they think about widespread adoption of this stuff
20:30 robotustra and what of it?
20:30 robotustra there are a lot of crazy and gready people arount the world
20:31 Jak_o_Shadows If I want a 3D printed bracket to slide over a bit of aluminium extrusion, what tolerances do I need on the bracket?
20:33 GargantuaSauce how thick?
20:33 GargantuaSauce even pla is reasonably compliant
20:33 GargantuaSauce if you want a friction fit you're in for a tough time though i think
20:33 robotustra it's better not to slide on aluminium
20:34 robotustra it's too soft and will wear fast
20:35 Jak_o_Shadows well, the bracket will be located and carry a deal of the force using some bolts, so not really a friction fit
20:35 Jak_o_Shadows and no, not sliding, just fitting over snugly
20:36 Jak_o_Shadows The aluminium profile, for example, has a 2mm thick straight bit. In the bracket, do I put that as 2mm, or a tiny bit more?
20:36 Jak_o_Shadows Or do i go screw it, it's going to be 3D printed after all
20:36 GargantuaSauce it really depends on your printing configuration
20:36 GargantuaSauce if it's super tight and calibrated the tolerance can be very low
20:37 GargantuaSauce otherwise you might need a whole millimetre
20:37 Jak_o_Shadows Is it generally easy to file/sand?
20:37 GargantuaSauce yes, or heat the extrusion and jam it on :)
20:37 robotustra I would print exact size and fit with file after
20:37 Jak_o_Shadows ha, ok
20:40 Jak_o_Shadows I have some thought about making a triangle back style prusa 3 out of this. If I had a set square, I might be able to do it ok
20:40 Jak_o_Shadows plus, robot arm
20:41 robotustra show it
20:43 Jak_o_Shadows Haven't got terribly far yet :P http://imagebin.org/279395 The inner bit is the alu extrusion.
20:52 robotustra shit with bricks http://www.youtube.com/watch?v=8BhJL1O7gmw
20:56 Jak_o_Shadows Right, so people use small screws to attach servo horns to brackets
20:57 GargantuaSauce yeah...plastic servo horns are not too awesome though
20:58 GargantuaSauce don't expect it to withstand much torque or weight bearing
20:58 Jak_o_Shadows The metal ones seem to hae the same hole sizes? Also, they're only 10.5kg servos.
20:58 Jak_o_Shadows (Was going to say i'm only going to lift 180g, but that's pretty meaningless isn't it)
20:59 GargantuaSauce yeah that'll probably be fine
20:59 GargantuaSauce and mix and matching horns+servos from different manufacturers is harder than you'd think
21:00 GargantuaSauce the number of teeth on the splines varies a lot
21:00 Jak_o_Shadows is your typical 3D printed thing have loose enough tolerances just to shove it in while hot?
21:03 GargantuaSauce if the printer is reasonably calibrated it should be fine with a pretty small gap
21:04 GargantuaSauce and that design is simple enough so that it'd be super easy to widen anyway
21:04 GargantuaSauce i was picturing something that actually interfaced with all of the interior edges of the extrusion's channel
21:05 Jak_o_Shadows I would if it weren't round, but because the throat narrows, I don't think it's worth it.
21:05 GargantuaSauce what i would do for that is make it taller so you can have two bolts going through it
21:08 Jak_o_Shadows Sorry, what? I was going to extrude that out along the aluminium profile (not in the profile, just in that direction of the actual aluminium), then probably do 2 screws going that way.
21:11 GargantuaSauce oh i am just reading the drawing wrong i guess
21:11 GargantuaSauce that sounds fine
21:24 Jak_o_Shadows http://imagebin.org/279400
21:26 GargantuaSauce cool
21:26 Jak_o_Shadows Provided I can get some screws for the servo horns the right size. The centre hole is to put the servo-attachment screw in.
21:27 Jak_o_Shadows 6mm wall, is that thick enough you reckon?
21:27 GargantuaSauce probably
21:27 GargantuaSauce the limiting factor is going to be the horn pushing far enough down on the spline to rub against the servo body
21:29 GargantuaSauce what i did for the hexapod which worked reasonably well was ignoring the edges of the spline altogether, and using a toothed washer and an overtightened bolt
21:29 GargantuaSauce wouldn't work as well against thermoplastic though, that was metal
21:37 Jak_o_Shadows Wish inventor had a 3/16" machine thread bolt in it's content centre
21:37 GargantuaSauce the spline's orifice is m3
21:43 Jak_o_Shadows So the end result would be similar to http://imagebin.org/279406 , but with more bolts
21:46 Jak_o_Shadows Hmm, it'd be nice to take some load off that main thing and put some over onto the other side eh.
22:12 MrCurious cut it, drill it, tap it, screw it!
22:12 MrCurious that could be a song
23:36 Casper Hi there, I just found a listing on ebay for some bearings... 3.89$ for 8x brand new 608 bearing... does that sound too low or about right?
23:37 GargantuaSauce is there such a thing as too low?
23:37 GargantuaSauce worst case ontario you've wasted four bucks
23:38 Casper 8, I need 2 sets
23:38 Casper :D
23:38 GargantuaSauce hehe
23:38 GargantuaSauce link to the auction?
23:39 Casper http://www.ebay.ca/itm/Set-8-PCS-New-Skate-Skateboard-Longboard-Stainless-Bearings-ABEC-5-608-2RS-Red-/300906879030?pt=LH_DefaultDomain_2&hash=item460f729836
23:39 MrCurious ty casper.
23:39 Casper MrCurious: ? you want some too? :D
23:40 MrCurious can never have too many at that price
23:40 Casper I think I'm gonna order 3 sets..
23:40 MrCurious good pla
23:40 MrCurious n
23:40 Casper can't be worse than those bearings that I get locally
23:41 GargantuaSauce yup imma get some too
23:41 Casper those 608 extended... man... they are so junk...
23:41 Casper huge play and brand new...
23:41 Casper the kind almost 2mm of play
23:42 Casper bought...
23:43 Casper and paid
23:43 Casper man...
23:43 GargantuaSauce aaand you'll get em in february
23:43 Casper it's scary how fast it can be to spend money online
23:43 Casper well, not in febuary...
23:43 Casper but in january
23:45 Jak_o_Shadows Hey, if you buy everything online early, you'll have it when you want to
23:45 MrCurious are they bad bearings? should i avoid?
23:46 Casper no idea, but those at the local store is junk
23:46 GargantuaSauce http://www.youtube.com/watch?v=sdm7gc4_Oww
23:46 GargantuaSauce i need a damn lathe
23:46 Casper http://www.vxb.com/page/bearings/PROD/8mm/Kit14047 ← that's what I actually need
23:46 Casper so I'll buy some bolts to assemble it
23:47 sper wonders if he can find those bolts... onlin
23:48 Casper … it's even tempting to save 2 bux and buy it online lol
23:48 GargantuaSauce i went to the only local place that has M3 bolts and paid 18 cents each for 8mm ones
23:49 GargantuaSauce was kiiiinda pissed off
23:49 Jak_o_Shadows I was looking up M2.5 bolts earlier, not particularly cheap in small lots