#robotics Logs

Jul 27 2018

02:10 AM rue_shop3: ouch, brused my hand taking apart a car jack
03:21 AM rue_shop4: M7x1... wtf!?
03:22 AM rue_shop4: who uses that!?!?!
04:55 AM rue_shop3: ok new nuts made for the speaker connectors]
04:55 AM rue_shop3: 3am
05:44 AM filiperibeiro: hello! Just one question. Should I only have a reference frame when I'm developing a station at Robotstudio or even robodk? If yes, why :)
06:58 AM Jak_o_Shadows: filiperibeiro, you should 100% define the reference frames
06:59 AM Jak_o_Shadows: I have no idea how to do this joint.
07:04 AM Jak_o_Shadows: yeah, ok. Simple simple joint, do the more complicated joint at the other end
07:05 AM Jak_o_Shadows: or rather, in the sorta middle
07:05 AM Jak_o_Shadows: that keeps driving it simple as well
08:30 AM Jak_o_Shadows: Starting to wonder if closed belts would be better
08:42 AM filiperibeiro: Jak_o_Shadows, I know it, but What i use to do is making my robot base as the reference, and then everything is oriented and positioned relative to it
08:42 AM filiperibeiro: As I've learnt everything alone I would like to know if this is a mistake or not
02:08 PM rue_shop3: I was thinking about making a pulse timer for my spot welder, but realized that it takes a lot of juice
02:08 PM rue_shop3: then I remembered I have some 1300A SCRs
02:09 PM rue_shop3: that'lll do for the ~20A it draws
02:36 PM theBear: i been musing over the same kinda massive-switching-device quandry myself a lot recently
02:40 PM theBear: saw a vid on youtube some jackass had a brand new cheap modern car batt, and basically just tickled a standard 3 spades + chassis style auto-relay with a button which in turn switched between the b att terminal and some squashed flat copper water piping that went to the spot weld tips... sure, he coulda been faking it on purpose cos he's some kinda sociopathic asshole, but either way, i don't see one of those little (ya know, roughly 1.5" cube
02:40 PM theBear: things, pretty sure they can't switch on a starter motor, but htey can do 100 or 200w's fer silly headlights indefinately... but erm, surely using any kinda relay (well, physical make/break anything) as the BIG switching device for even a tiny spot-welder is erm, far from a long-term solution ? then i also mused a bit about massive relays like mains "breakers" i think they call 'em, you know, massive multi hundred watt 3phase breakers with the
02:40 PM theBear: switches physically coupled and a big coil on the side that can flip it like a relay, and just generically MASSIVE contact relays, and wondered if there some practical-to-diy (if yer us, not a normal person of course) way to protect yer huge contacts from arcing, ya know, maybe some easy-to-flood-and-seal noble gas or i dunno, non-conductive oil submersion of some kind ?\\
02:41 PM rue_shop3: even the switch built into the welder can stick on me
02:42 PM rue_shop3: I'm always ready to move fast
02:42 PM rue_shop3: just a spot welder
02:50 PM theBear: it's true, and i figure if yer abusing either very unsuited caps in MASSIVE banks, or like myself (at least short-term/mk1 (i got some things that need welding sooner than leter)) abusing a poor standard mid-sized flooded car batt as your entire power source/bulk storage, you wanna be ready to perform major damage-control manouveres at all times <grin>
06:55 PM Jak_o_Shadows: theBear, are you sure it was a normal battery? Could it have been one of those jump-starter fire-starters?
07:17 PM rue_: ok, I got the anchors for the solar panels on the roof
07:18 PM rue_: http://ruemohr.org/~ircjunk/images/p1100384.jpg
07:19 PM rue_: should I make a power cart for moving things around the yard?
07:22 PM rue_: the pwm off the controller is 16Khz
07:22 PM rue_: they use relays for reversing
07:51 PM Jak_o_Shadows: oh dammit
07:51 PM Jak_o_Shadows: it's going to not intersect
07:52 PM Jak_o_Shadows: and I'm a third into the print
07:56 PM Jak_o_Shadows: going to intersect*
07:56 PM Jak_o_Shadows: But it might work out for the best.
08:11 PM rue_: 8-|
08:11 PM rue_: mmmm
08:11 PM rue_: 5pm aleady
08:18 PM Tom_shop: yeah, do you know where your robot is?
08:23 PM Jak_o_Shadows: and in about 5-10minutes, we'll see how well my printer bridges 23mm
08:25 PM Tom_shop: should be fine
08:25 PM Tom_shop: i did like 2.5" bridge on some 2.5" hdd adapters
08:26 PM Jak_o_Shadows: It's a new thing for me.
08:26 PM Jak_o_Shadows: and I've never tried to optimise any settings for bridging.
08:26 PM Jak_o_Shadows: But there's enough material above, that even if I get some drooping, I can just cut it away
08:29 PM Jak_o_Shadows: wow, jup, worked perfectly
08:29 PM Jak_o_Shadows: Why did I not start with PLA?
09:36 PM Jak_o_Shadows: Guy stole my idea
09:36 PM Jak_o_Shadows: https://www.youtube.com/watch?v=nSMCvMjL5hE
09:36 PM Jak_o_Shadows: And is probably doint it at a better scale than I am
11:35 PM Jak_o_Shadows: Next leg profile: http://pasteall.org/pic/show.php?id=483cc913da76303f918d6e3459b77dcc
11:35 PM Jak_o_Shadows: The motors are too small -- but I want to get some idea of the motion
11:35 PM Jak_o_Shadows: I'll just counterbalance it for now
11:38 PM rue_shop3: oooh yea
11:38 PM rue_shop3: hmm
11:38 PM rue_shop3: whats bridged?
11:39 PM rue_shop3: and why not a lower ratio? you dont need 180 do you?
11:39 PM rue_shop3: human joints seem to mostly be shy of 90
11:40 PM rue_shop3: Jak_o_Shadows, whats the belt pitch?
11:44 PM Jak_o_Shadows: One of the parts was printed horizontal, had a bridge in it, for the servo hole
11:44 PM Jak_o_Shadows: Why not a lower ratio? Because I didn't think of it when I printed the lower leg.
11:45 PM Jak_o_Shadows: That said, Having 120ish would be nice
11:47 PM Jak_o_Shadows: 2mm belt? It's the standard 3d printer one
11:51 PM rue_shop3: hmm
11:51 PM rue_shop3: looks like it printed ok, does it jump easy?
11:55 PM Jak_o_Shadows: Nah, it's stretched pretty tight