#robotics Logs

Mar 24 2014

01:05 MrCurious would someone somwhere in the world get off their butts and do something news worthy
01:07 anonnumberanon Yeah SpaceX is sending a rocket that may be able to land back on Earth next Sunday. This first time people say they might try it first on a barge at sea.
01:08 rue_more the barge DID float, who the hell blew the huge hole in it!?
01:08 MrCurious the iranian fake us carrier barge
01:08 MrCurious ?
01:08 rue_more the landlocked aircraft carrier?
01:09 MrCurious i thought it wa a barge that they would tow out to sea and make a propaganda movie from
01:09 MrCurious http://www.usatoday.com/story/news/world/2014/03/22/iran-fake-us-aircraft-carrier-nimitz/6740979/
01:10 MrCurious doesnt look like our carriers
01:10 anonnumberanon ^^ this is why we can't have nice things
01:17 MrCurious re:flight 370.... i have an idea... how about making it so the pilots CANNNOT disable telemetry beacons...
01:17 MrCurious that seems to be a ability really only needed by military planes
01:25 rue_more what are you saying
01:26 rue_more are you saying that farmers dont need aircraft carriers for crop dusting planes!?
01:28 peepsalot rue_more, re: servos i want to run it in continuous mode for extended periods
01:29 rue_more well then a hobby servo wont last long
01:29 peepsalot i got one with metal gears, but i suppose the motor is the weak point then?
01:29 peepsalot brushes wear out, or overheating?
01:29 rue_more gears and motor wear out
01:31 peepsalot how many hours of operation would you guess?
01:32 anonnumberanon On my to do list, test a part to see when it breaks.
01:33 peepsalot btw i found this site today. seems like a nice resource http://www.servodatabase.com/
01:36 rue_more odd I'm sure the price for a hs422 is about 9.99
08:59 rue_more this must be a zombnie virus
09:00 rue_more its gonna kill me, then I'll be a zombie
11:58 anton164 Hey, is it cool to ask basic math questions related to robotics here too?
12:00 anton164 I’ll just ask, bear with me though, I’m very new and trying to build intuition :)
12:00 anton164 I’ve been given the locations and orientations of two coordinate frames ( T and B,) within a world frame, now I’m supposed to find the transformation matrix expressing the position and orientation of T with respect to B. The motivation behind this is that I could have a vector within frame T and transform it to frame B by multiplying with the transformation matrix, right?
12:03 anton164 Actually, I see that I’m wrong, it should be a vector within frame B that is transformed to frame T by multiplying by the transformation matrix!
12:08 GargantuaSauce are T and B "siblings" or is one the parent of the other in the hierarchy
12:08 anton164 T is the tool frame, B is the base frame
12:08 GargantuaSauce yeah you have it right then
12:09 anton164 Great, cheers
12:10 GargantuaSauce actually it's backwards
12:10 GargantuaSauce you need to multiply the vector in frame B by the inverse of T
12:11 GargantuaSauce if the vector were in T's frame you'd multiply it by T's matrix to get it in B
12:18 anton164 Inverse of T?
12:18 GargantuaSauce yeah, invert its matrix
12:18 GargantuaSauce the matrix represents the transformation from T to B
12:19 GargantuaSauce so to go from B to T you need its inverse
12:20 anton164 Oh, so M subscript (T) superscript(B) is from T to B?
12:20 GargantuaSauce i have no idea
12:21 anton164 Alright, but isn’t it more natural to start with the base frame and find the transformation matrix that transforms vectors to the tool?
12:21 GargantuaSauce yes
12:21 anton164 Ok yeah, so that’s what I’ll try to do then :)
12:22 GargantuaSauce well maybe, i guess a case could be made for going in either direction
12:22 GargantuaSauce either way it's just a hierarchy of transformations you need to be able to navigate through in both directions
12:23 anton164 Yeah, thanks, I think I got the gist of it
17:12 peeps[work] are there driver ICs for 3wire brushless dc motors that can accept step/dir inputs like a typical stepper driver?
17:42 GargantuaSauce i don't believe so
18:11 peeps[work] but i *want* it
18:11 peeps[work] :(
18:19 GargantuaSauce i don't think you really do
18:19 GargantuaSauce whether they're used at low speeds or as servos or at high speeds they're generally in need of more complex, dynamic control
18:20 GargantuaSauce and you can't really make big assumptions about their acceleration the way you can with steppers
18:21 GargantuaSauce also i haven't found any monolithic driver ICs that push more than half an amp or so
19:21 rue_more peepsalot, 3 phase motors dont really step
19:21 rue_more they more just run at constant speeds well
19:21 peeps[work] why not
19:21 rue_more no holding torque
19:22 rue_more its like trying to turn an alternator into a stepper motor
19:22 rue_more yea, it works, but ughckgh
19:23 peeps[work] well i don't need a lot of holding torque cause it's going through a bunch of gears anyways
19:24 rue_more there are speed/dir ones
19:24 rue_more lots of them you give a clock rate for the speed
19:25 rue_more but you cant count steps on it
19:55 ShH_ s
19:57 GuShH_ theBear: are you alive?
20:01 GargantuaSauce http://www.youtube.com/watch?v=rBmnQN78aZU
20:01 GargantuaSauce that poor drill
20:02 ShH_ is pissed off, but when isn'
20:03 GargantuaSauce who pissed in your cheerios today
20:06 GuShH_ went to your run of the mill big ass store to get a wood router... last unit, not the one I wanted.. but I got it anyway, when I'm about to pay it's quite normal to request a check up to see that nothing is missing because now they don't have a full money return policy, just store credit, so all the more reason for that... clerk first attempted to open the box, damaged it in the process with the box cutter (I was about to boil,
20:06 GuShH_ he left deep marks on the plastic case) then refused to open it until I paid for it, which I did, even though at this point I wanted to punch him in the neck, now I ask him to open the damn box, he refuses and tells me there's a "work table" by the end of the corridor, that I could test it over there. I refuse, I begin to open it right there and he threatens to call security. I JUST FUCKING BOUGHT THE THING I CAN OPEN IT ANYWHER
20:06 GuShH_ E I WANT!!!, then he closed up and walked out. What the fuck?, so now I'm stuck with something I didn't want, something I couldn't check, and something I won't get my money back if it's damaged? not even a replacement since it's the last unit. Fuck. Me.
20:06 GuShH_ Plus they request your ID for purchases after a certain amount, but they don't give you a proper receipt... which is technically illegal, but who gives a fuck in this country.
20:08 GargantuaSauce that's pretty damn sketchy
20:10 GuShH_ I'm sick of the stores here
20:10 GuShH_ they're run by drug addicts.
20:12 GuShH_ also I feed that mother fucker for all I know, they should respect their customers.
20:13 GuShH_ one of these days
20:13 ShH_ shakes
20:33 GargantuaSauce so it's not the one you wanted...will it still suffice?
20:33 GargantuaSauce or do you essentially have an expensive doorstop
20:35 GuShH_ GargantuaSauce: more or less
20:35 GuShH_ this one doesn't have all the fences/guides I wanted, only a parallel fence...
20:36 GuShH_ I could try reselling it for the same price, to recover the money... but that might take time.
20:36 GuShH_ let's see, I couldn't find the model listed anywhere and they wouldn't open it until I paid for it, so I couldn't know those extra guides weren't included
20:37 GuShH_ tomorrow I'll visit other stores... buy the one I wanted, see if I can resell this one so I can recover the money. I can't think of anything else, thanks to these stupid fucks.
20:38 GuShH_ their descriptions are always wrong, like when I bought the skilsaw it said "kit" and it didn't include the carry case or anything else, it was just the saw, but it said "kit" on the description, I discussed this with the "manager" and got nowhere.
20:38 Tom_itx poor GuShH_
20:39 ShH_ slaps Tom
20:39 GuShH_ It's not my fault these weasels are allowed to get away with anything
20:39 GuShH_ just because they're a big store.
20:40 Tom_itx don't support big stores
20:40 GuShH_ I try not to
20:40 Tom_itx they hire minimum wage
20:40 GuShH_ I needed screws to finish a project but I left them, I'll buy them tomorrow at the hardware store (mom & pop)
20:40 Tom_itx minimum wage doesn't give a shit
20:40 GuShH_ at least the small stores are friendly, if they don't have it they'll tell you where to find it
20:41 Tom_itx if i don't know what i'm getting no matter what or where, i don't get it
20:41 GuShH_ but in this case, the prices were lower at the bigger store, they just didn't have any more stock of the unit I wanted, so I got a more expensive one (assuming it had the same amount of guides, it didn't)
20:41 GuShH_ yeah but you live in a country with open imports
20:41 GuShH_ and no inflation at least not like we've got here
20:41 GuShH_ if you have the money buy it now, otherwise tomorrow you won't be able to afford it, or there won't be any left.
20:42 GuShH_ that's Argentina.
20:42 GuShH_ anyway I'll find the one I wanted tomorrow, sell this shit, it's never been used. I'll plug it in to know it "spins" and then it goes back into the case.
20:42 GuShH_ they retail for more online, who knows why.
20:42 ShH_ just wants his money
21:33 rue_more if they are gonna tripple the proper price, they better expect to give away 2 for every 1 they sell
21:47 GuShh_Lap2 rue_more: ?
21:49 GuShh_Lap2 MrCurious: I got a "steel and iron" blade for the skilsaw, I wonder if I could use it on aluminum as well? it seems to be HSS, no carbide. angle must be right but perhaps not enough clearance for aluminum?
21:49 GuShh_Lap2 I'll get ya a pic if need be
21:50 rue_more you can just use a carbide blade for aluminum
21:54 GuShh_Lap2 rue_more: no.
21:54 GuShh_Lap2 the one I have has absolutely the wrong angle for metal
21:54 GuShh_Lap2 it's for wood.
21:55 GuShh_Lap2 so I bought one for steel (couldn't find the multi-material ones at that particular store)
21:55 rue_more I just about lived beside a boat fab shop that used nothing but carbide blades
21:55 GuShh_Lap2 THEY ARE NOT ALL THE SAME SIR.
21:56 GuShh_Lap2 positive, negative, clearance, all matters.
21:56 GuShh_Lap2 ask someone else if you never trust what I have to say..
21:56 GuShh_Lap2 I actually did that yesterday, asked MrCurious.
21:56 MrCurious ?
21:56 GuShh_Lap2 even though I was already well informed about how stupid it would be to use a ripping carbide blade on metal.
21:57 GuShh_Lap2 but I guess if you were insane, didn't care for collateral damage or ruining your stock, perhaps you could use a framing blade on aluminum.
21:57 MrCurious wrong slope, and your blade will bounce like MAD, or worse yet, bite in and stop and burn your motor
21:57 GuShh_Lap2 as you could try and cut your meat with a spoon.
21:57 GuShh_Lap2 MrCurious: tell rue..
21:57 rue_more they told me they just used carbide wood blades
21:57 MrCurious using wood blades witl aluminum results in spalting, vibration and generally shit cuts
21:57 GuShh_Lap2 yes carbide is carbide, but angles do matter
21:58 GuShh_Lap2 actually no, carbide comes in very different grades of quality
21:58 MrCurious use a carbide designed for aluminum, and air or some other coolant
21:58 MrCurious and get glassy perfect cuts
21:58 GuShh_Lap2 some shit carbide delaminates when you stare at it.
21:58 MrCurious the angles are the key...
21:58 GuShh_Lap2 MrCurious: tell rue!
21:58 rue_more the main saw I saw there was a crosscut saw, it was just one for wood
21:58 MrCurious i just did
21:58 GuShh_Lap2 I got one for steel it must be HSS, I might try that for the time being
21:59 MrCurious he dont want to listen, he can waste money, risk health, and equiptment and stock, then finally learn to do it right
21:59 rue_more I'm telling you these guys were a boat factory
21:59 MrCurious with aluminum of 1 or 2 mm, might get away with it
21:59 MrCurious go 1/2" thick or more... nd you wont
21:59 rue_more I must have watched them turn out like 20 hulls while I was there
22:00 rue_more this was 1/4" to 3/4" plate
22:00 MrCurious then they used a caarbide blade with angles designed for non ferous metals
22:00 rue_more they told me they were just carbide wood blades
22:00 Tom_itx fine tooth
22:00 GuShh_Lap2 I rue it when it comes to abrassive wheels on the chop saw, I do use regular ones (for steel) on aluminum, but I do cut steel quite often so they never gum up, it works but it heats up your stock (not ideal at all) and leaves a tiny burr, also not ideal. it removes just about the same amount of material but it's way slower.
22:00 rue_more yea, I think they were fine tooth
22:00 GuShh_Lap2 I only do that because I can't find the right blade for the chop saw.
22:00 MrCurious i would tell you that too, so you failed to get results and came to me with work i could over charge you for
22:00 GuShh_Lap2 and it seems I can't find one for the skilsaw either
22:01 GuShh_Lap2 tooth count, angle and clearance are the keys in blades
22:01 GuShh_Lap2 they all vary!
22:01 Tom_itx i've got some 60 tooth but don't plan to use them on metal
22:01 Tom_itx tri cut even
22:01 Tom_itx made for plastics
22:01 GuShh_Lap2 the boat guys were probably using the multi-grade which also cut MDF
22:01 MrCurious a carbide blade for hard wood on my 14" chop saw when i tried to use it for aluminum resulted in blade bouncing, singing, and a truely shit cut
22:01 GuShh_Lap2 so you could call it a "wood saw" but it's designed for multiple types of material
22:01 MrCurious cooling/lubrication/chip clearance is key
22:02 GuShh_Lap2 lol
22:02 MrCurious but the blade angle is the cheapeast easiest way to improve aluminum cuts
22:02 MrCurious you will listen or you wont.
22:02 GuShh_Lap2 MrCurious: deviant assholes!
22:02 MrCurious best of luck
22:02 Tom_itx wood blades have more agressive angles i know
22:02 GuShh_Lap2 Tom_itx: yeah it says alu, plastic, laminate
22:03 GuShh_Lap2 couldn't find those in stock
22:03 MrCurious the agressive slope blades bte in way too much
22:03 MrCurious bite
22:03 GuShh_Lap2 MrCurious: I just took a close look at the angle and amount of teeth (only 24 on a framing blade) and I realized it would be a stupid idea to take it to any sort of metal
22:03 Tom_itx yeah
22:03 Tom_itx i agree
22:03 MrCurious yes it was
22:03 GuShh_Lap2 "looks wrong"
22:03 MrCurious i was lucky i didnt toss off carbide bullets...
22:04 Tom_itx like i said, i've got some 60 tooth that probably would work but i'm not gonna find out
22:04 GuShh_Lap2 http://gushh.net/tmp/p_20140324_233458.jpg that's what I got today, in theory it could work with aluminum... even if it's a cheap one.
22:04 Tom_itx for one thing they cost too much to have sharpened
22:05 GuShh_Lap2 somehow I feel it might "gum up" but I'm not sure.
22:05 MrCurious yeah thats going to need air or water or non sticky coolant
22:05 GuShh_Lap2 128 teeth
22:06 GuShh_Lap2 I actually need to cut some 1/2 angle iron and the chop saw was leaving massive burrs, so this could come in handy
22:06 MrCurious aluminum likes to melt at temperatures present in cutting operations
22:06 MrCurious then it likes to solidify shortly after
22:06 Tom_itx use an abrasive wheel for the angle iron
22:06 MrCurious this causes undesirable results
22:06 GuShh_Lap2 Tom_itx: I have
22:07 GuShh_Lap2 I also changed brands for a Dewalt wheel on the chop saw
22:07 GuShh_Lap2 those are like 12 or 14 inch? I forgot
22:07 GuShh_Lap2 but it's stil leaving burrs
22:07 GuShh_Lap2 MrCurious: you'll see that on drill bits, lathe tools, etc. if you are doing it wrong.
22:08 GuShh_Lap2 once the alu "welds" to the tool it begins to mess with your cut
22:08 GuShh_Lap2 until it clears out or you remove it yourself
22:08 Shh_Lap2 was doing it wrong at one po
22:08 MrCurious once it welds to the tool, your tool will never perform asgood as before it didthat
22:09 rue_more thats why I was surprised
22:09 MrCurious even if you remove it, as it will leave very thin micron layers that helpit reform on there next use
22:09 GuShh_Lap2 of course with HSS I dress the edge all the time on the bench grinder
22:09 MrCurious if you dont believe gush and i, you could ask the russian....
22:09 GuShh_Lap2 I don't think it can damage the carbide
22:09 MrCurious he has plenty of experience with working with aluminum
22:10 Tom_itx who's doubting you?
22:10 MrCurious rue according to gush
22:11 MrCurious well, that killed that thread....
22:11 rue_more I'm just saying I was across from a factory, they used carbide wood bits
22:11 Shh_Lap2 shakes
22:11 MrCurious wood bits or blades
22:11 rue_more circular saw blades
22:12 MrCurious saw blades and carbide router bits are different bests
22:12 GuShh_Lap2 wait you can use a carbide router bit on aluminum?
22:12 GuShh_Lap2 not like I'm going to try it out until I get the other one, this one is going for sale.
22:12 MrCurious clearly you have to buy a wood blade and a aluminum blade and do a comparison...
22:13 Shh_Lap2 calls circular saws "skilsaws" because skil invented them as far as he k
22:13 MrCurious i am ok with saying sorry i was foolishly wrong
22:13 MrCurious skillsaw cutting aluminum?
22:13 GuShh_Lap2 I remember watching a documentary on tools and they had the first one on display, it was their anniversary I think... heavy beast.
22:13 MrCurious does not wnt
22:13 rue_more I'm saying that I dont care if you say that by the book it wont work, I saw people DO it, continiously
22:14 MrCurious must have a been a lubricant system, or coolant system or vaccuume system you failed to note
22:14 rue_more no
22:14 rue_more I watched them do it
22:14 MrCurious aand it produced perfectly flat cuts on 3/4" sheets?
22:14 rue_more I also watched them spending hours cleaning the weld joint edges
22:14 GuShh_Lap2 MrCurious: wait, what's the difference from a skilsaw to a contractor saw? it's the same motor, blade, it's just got a shitty table with a fence in between the two.
22:15 GuShh_Lap2 maybe you get the option to stack blades on the latter...
22:15 GuShh_Lap2 don't know on the regular contractor saws
22:15 rue_more not perfect cuts, there is about 20 thou of tooth difference
22:15 GuShh_Lap2 a proper table saw does let you to.
22:16 GuShh_Lap2 cleanup after welding depends on the end result you want...
22:16 MrCurious well, when a table saw launches a work piece... its a projectile... if the skill saw gets launched, then its a projectile with a powered blade...
22:16 MrCurious it is out of my expertise doing it with a skill saw
22:16 MrCurious when i work aluminum, i am trying for precision
22:16 GuShh_Lap2 the saw would want to go up
22:16 MrCurious not for eyeballin strait lines
22:17 GuShh_Lap2 you have parallel guides, you don't get precision on a contractor saw anyway
22:17 GuShh_Lap2 it's meant for cutting timber.
22:17 GuShh_Lap2 precision on frame work and such is meh.
22:17 GuShh_Lap2 actually most have plastic fences!
22:17 GuShh_Lap2 which flex
22:17 GuShh_Lap2 I was looking at a couple of those the other day
22:17 MrCurious sliding table...
22:18 MrCurious properly tuned
22:18 GuShh_Lap2 a proper table saw is not a contractor saw!
22:18 MrCurious you of all people should understand the value of tuning the tool!
22:18 MrCurious my contractor saw is a sliding table one
22:18 GuShh_Lap2 one is a high end car, the other is a fiat 600 with a massive rat living inside.
22:18 MrCurious i paid a wee extra
22:19 GuShh_Lap2 I don't know what's involved in tuning a contractor saw
22:19 GuShh_Lap2 hammer?
22:19 MrCurious it isnt a proper console saw with cast iron bed that wont moov during earthquakes and volcanic eruptions..
22:19 GuShh_Lap2 I wish I had one of those
22:19 MrCurious maybe one day when i feel insane enough to drop 2k on a saw
22:19 GuShh_Lap2 with a perfectly flat table
22:19 MrCurious lots and lots of calippurs and screw adjustments
22:19 GuShh_Lap2 2k is what a contractor saw costs here...
22:19 GuShh_Lap2 sadly
22:19 MrCurious in order to get 90 deg cuts
22:19 MrCurious OMG
22:20 MrCurious 2k gets you a saw that is easily a 4 - 6 man carry here
22:20 MrCurious a guy can dream.... http://www.grizzly.com/search/search?q=table%20saw&cachebuster=7922561797313392
22:20 GuShH_ ugh
22:20 GuShH_ I use the skilsaw on thin timber for home projects, there are also things too big to cut on a contractor saw without a jig of some sort (say another table at the same height on the other end of the room)
22:21 GuShH_ 11k!!!!
22:21 MrCurious cabinet table saw.... thats the one i crave
22:21 GuShH_ some of those < 2k look neat
22:22 GuShH_ these are all considered "professional tools" here, and cost way more than they should.
22:22 MrCurious gush... you really need to get out of argentina and get into a nice first world country
22:22 GuShH_ it's unthinkable for a homeowner to have or want one of these... same with a lathe or a milling machine.
22:22 GuShH_ here nobody does jackshit.
22:23 GuShH_ MrCurious: selling all my stuff could take years, and figuring out a way to get out of the country with the money may take a lot of money in it's own. because we're on lockdown they don't want you to leave.
22:23 MrCurious hey GuShH_ .... http://www.grizzly.com/products/category/465000
22:23 GuShH_ I am an Italian citizen... it's just easier said than done.
22:24 GuShH_ MrCurious: those are horrible.
22:24 GuShH_ don't ever get any "combo" tool.
22:25 MrCurious how bout this one? http://www.grizzly.com/products/G4002
22:25 GuShH_ nice lathe
22:25 GuShH_ for being chinese that is
22:25 MrCurious nothing wrong with buying from glizzry
22:25 GuShH_ can't in my case.
22:26 GuShH_ but they're the same china shit sold anywhere else
22:26 GuShH_ different colour.
22:26 rue_more gearhead, nice
22:26 GuShH_ 300 for the stand? jeeze
22:26 GuShH_ it's not even cast iron
22:27 GuShH_ maybe I should move next door to MrCurious
22:29 GuShH_ seems some of the stands have cast iron legs, hrm
22:29 GuShH_ but very thin, hollow, unlike good ol' lathes
22:50 MrCurious hmmmm http://www.dailymail.co.uk/sciencetech/article-2588040/Is-terrifying-robot-Animatronic-dancer-stares-gyrates-Blurred-Lines.html
23:16 GuShh_Lap2 MrCurious: hmmm indeed
23:17 GuShh_Lap2 what's with the face
23:18 GuShh_Lap2 ITS A DUDE
23:18 MrCurious drives the pervs away
23:19 GuShh_Lap2 neck and face are covered for a reason! shemale robot dancer!
23:20 GuShh_Lap2 must be robotustra's latest creation
23:22 GuShh_Lap2 MrCurious: you should invest in this, there's a huge market in Japan for dancing robot ladyboys.
23:25 MrCurious dont you mean in S.A. whereits all the rage
23:48 GuShh_Lap2 No, the hesheits will first be delivered to Japan, surplus goes to S.A.