#robotics Logs

Jan 04 2012

04:10 dunz0r rue_mohr: I get 100% packetloss when pinging it
09:05 rue_house tom?
09:05 rue_house amee2k, ?
09:05 rue_house hmm I wonder
09:05 rue_house !thislog
09:05 rue_house !thislog
09:05 rue_house hmm
09:06 rue_house !thislog
09:06 tobbor This one: http://rueshouse.dyndns.org:82/~ircjunk/irclogs/html/%23robotics-2012-01-04.html
09:06 rue_house http://rueshouse.dyndns.org:82/~ircjunk/irclogs/html/%23robotics-2011-01-04.html
09:07 rue_house oh yea, 8031
09:11 rue_house DagoRed:damnit, my router is dying again
09:11 rue_house I use a pc, its been running for 6 years
09:11 rue_house dont know why you people are so into those troublesome little boxes
09:22 rue_house http://xkcd.com/806/
09:22 rue_house hahahahahha
09:28 dunz0r I've got a nice big ol' Juniper J4350 for a router.
09:28 dunz0r Overdimensioned as hell for my puny home network.
09:28 dunz0r :D
10:30 amee2k rue_house: mmh?
10:30 amee2k whats buzzin?
14:52 SolarNRG Hi all
14:53 SolarNRG I have a question
14:53 SolarNRG Does anybody here know about alloying Lithium and Aluminium?
15:08 amee2k sounds nasty >_>
15:09 amee2k sounds like metal fire if you screw it up
15:13 SolarNRG Is there a way of making an airtight box that can withstand at least 660 degrees C?
15:14 SolarNRG This is so I can make strong, lightweight gears for a lightweight hi-speed hi efficiency planetary gearbox
15:17 amee2k from what i remember planetary gearsets aren't efficient
15:17 amee2k but i'm not really a mechanics expert there
15:17 amee2k how about welded steel?
15:35 amee2k SolarNRG: i think you'll have to elaborate on that one... lots of materials can handle that temperature reasonably but you'll be getting into a fairly awkward area of high temperature engineering there
15:36 amee2k for example, you'll have to take thermal expansion into account for the temperature swings during power-up and shut-down
15:36 amee2k seals that are liquid and air tight at operating temperature may start leaking when they cool down
15:37 amee2k gears that run smoothly at room temperature may jam when they reach operating conditions
15:47 SolarNRG So I need to design a seal that has room to expand and contract yet is still airtight, what about a ring that has a gap parallel to the air duct instead of around the air duct so it expands parallel instead of perpendicular?
15:48 SolarNRG I'm guessing sticking lithium battery strips into molten aluminium is not smart
15:48 SolarNRG So I think it can only be done in an oxygen free environment
15:48 amee2k i'd say it won't mix due to the oxide layer on the aluminium
15:49 SolarNRG But when you melt aluminium isn't he oxygen released?
15:49 amee2k worst case you burn down your place by starting a metal fire and when the fire brigade arrives the house explodes
15:49 SolarNRG Back yard job def
15:50 amee2k oxide != oxygen
15:51 amee2k its not like there are bubbles in it. the only reason we can have aluminium stuff around is because the surface reacts with oxygen from the air and forms a layer on top
15:51 amee2k that is why aluminium almost always has a slightly dull look, especially if it has been sitting around for a while
15:52 amee2k the oxide layer covers the surface and doesn't flake off like rust on iron. if it weren't for that effect, elemental aluminium would burst on fire the moment it comes into contact with air
15:52 SolarNRG How do you separate the oxygen from aluminium?
15:52 KongfuPanda what sounds more enthusiastic "ignited my passion " or "fuelled my passion" for this field
15:53 amee2k that is why aluminium is fairly difficult to set on fire, but when it does burn, it'll keep burning as long as there is ogygen
15:54 SolarNRG I have a solar reflector that follows the sun
15:54 SolarNRG And at its focal point it gets very hot
15:54 amee2k it'll even rape other oxide molecules and take their oxygen atoms, like iron rust or even water. trying to extinguish a metal fire usually results in something close to an explosion
15:54 amee2k take a look at thermite welding for example
15:54 SolarNRG I was thinking of having a fiberglass insulated ceramic mold at the focal point and painting it oven black to absorb the light energy
15:55 SolarNRG Themite burns through basically anything
15:55 amee2k lol
15:55 amee2k thats what she said
15:55 amee2k and by she, i mean the shemale on mythbusters
15:56 SolarNRG I was thinking if I filed down aluminium cans, old phone batteries 2.3%weight and a bit of copper powder I can make really lightweight and strong gears that may make a running robot
15:56 SolarNRG I currently use steel gears, they are very good but they are heavy
15:56 SolarNRG Aluminium, lithium and copper are all back yard melting temperatures
15:57 SolarNRG But lithium reacts to oxygen and so does aluminium
15:57 amee2k thermite is aluminium or magnesium and iron oxide. when it burns, it creats aluminium oxide and elemental, molten iron. with a ceramic cast to direct the molten iron, you can let it flow into the joint and make welds that would be impossible without really heavy equipment in a factory
15:57 SolarNRG This is how train tracks are made
15:57 amee2k small scale processing liquid aluminium is usually done by adding weird stuff that forms a thick layer of airtight slag on the pool of metal
15:58 amee2k yep
16:00 amee2k anyway, alloying aluminium at home is probably extremely difficult and somewhat dangerous unless you know a lot of metallurgy
16:00 amee2k and even alloyed i don't think it'll be suitable for making high temperature precision mechanics
16:00 SolarNRG So if I Make a plexiglass chamber with some gloves going in and I use a vaccum cleaner to pump out the air and I carefully put phone batteries in there and take the lithium slithers out, they won't burn will they?
16:01 SolarNRG The gears when made are only to be used for ambient temperatures
16:01 SolarNRG Its to make a running robot!
16:01 amee2k i'd say a vacuum cleaner is never going to get up enough vacuum. you'll need a proper vacuum pump for that
16:01 SolarNRG They cost about a hundred quid from RS, thanks for that info amee2k
16:02 amee2k you'd have to dive into the properties here... you need to lower the pressure enough so the partial oxygen pressure makes combustion impossible
16:02 amee2k i'd try flushing the processing chamber with an inert gas like nitrogen. you'd have to check that it is truely inert with the materials involved
16:03 SolarNRG Hmm nitrogen
16:03 amee2k i'd also double check that lithium is present in elemental form in the batteries
16:03 amee2k that it is participating in the reaction doesn't mean it can't be bound in some compound or diffused into some internal structure
16:04 SolarNRG Hmm, perhaps I would be better off buying lithium bar from a chemistry wholesaler
16:04 amee2k yeah
16:04 SolarNRG What about gringing up coca cola cans for aluminium?
16:05 amee2k especially if you're ghetting up the process, having a good idea what your source materials are like is important
16:05 amee2k aluminium bar stock is cheap
16:06 amee2k you'll rarely have the means to accurately confirm your progess or the quality of the resulting product when doing fancy industrial processes at home
16:06 SolarNRG Can't I just brim-full back lithium bar and bean cans into my ceramic mold and have a heavy ceramic lid on top and superheat it? Surely some of it will react to the air but eventually the air will be used up
16:07 SolarNRG Well I can test the gears, I figured bean can gears are just going to shear
16:07 amee2k so you need to know your source material, and the product quality strongly depends on your knowing what you are doing and accurately performing the procedure
16:07 SolarNRG Al-Li seems an impressive material
16:08 amee2k well, making sure it'll mix as desired is another story. you should probably find someone with better metallurgic knowledge there than me
16:09 amee2k the problem with the oxide layer isn't that some material is missing
16:09 SolarNRG How do I find an expert metallurgist?
16:09 amee2k it forms a physical barrier that prevents the involved materials from contacting each other
16:09 SolarNRG Your information so far has been very useful thank you
16:09 amee2k sort of like the rubber layer on a filled water baloon
16:09 SolarNRG Like putting oil on water to stop flies breeding?
16:09 SolarNRG I get it
16:10 SolarNRG I'm sure you're very busy, but if you've got time, could you please have a look at my solar project I've been working on so far?
16:10 amee2k i'm not sure if your densities are different enough to form a phase barrier, but it you just let it sit there i'd say you're unlikely to get an even mix
16:11 SolarNRG Sounds like you've got to superheat and stir this mix in a vaccum
16:11 amee2k i'm not much into solar stuff, really. i just hang around with lots of mechanical engineers sometimes :)
16:12 SolarNRG I do a lot of work with gears, stepper motors, LDRs, arduinos
16:12 SolarNRG And I glue lots of mirror tiles onto sky dishes to concentrate light energy
16:12 SolarNRG I'm hoping to use this system to make cheap metal parts
16:12 amee2k physically stirring it will help, but i'd say you also need to find the right temperature for it to work. at least i'd assume that from my welding experience
16:13 SolarNRG Lithium's melting point is lower than aluminium but aluminium is about 660degC
16:13 amee2k temperature control is important for lots of processes that involve molten metals and other stuff
16:14 amee2k "hot enough so everything gets wobbly" usually doesn't cut it. or at least doesn't give very predictable results
16:15 amee2k with iron and steel you can usually tell from the color of the glow what temperature you are at. i don't think that'll work for low temperatures like with aluminium
16:24 SolarNRG Well steel you're dealing with hot temperatures before it wants to do anything
16:24 SolarNRG aluminium and lithium are both highly reactive to air
16:25 SolarNRG and don't require very high temperatures to melt
16:25 amee2k yeah, iron based materials start glowing visibly well before you're about to do anything to them, so it is a useful indicator there
16:26 amee2k not sure how you could get a decent estimate for your temperature ranges... as i said my wisdom won't get you all the way
16:27 amee2k you'll likely have to take this to someone with more experience with light alloy processing than me if you want to get useable results :)
22:12 thylane http://www.youtube.com/watch?v=91XqrzFhTWk
22:26 Jora hi
22:31 SolarNRG Hi guys
22:31 SolarNRG I have a question regarding planetary gearboxes
22:31 SolarNRG http://a8.sphotos.ak.fbcdn.net/hphotos-ak-ash4/387189_211239715631251_100002356712178_470466_1338376651_n.jpg
22:31 SolarNRG This is a crude illustration
22:31 SolarNRG Its an idea to use cheap recycled washing machine motors to drive an electric car
22:32 SolarNRG and even if one motor fails the other 5 motors still churn the drive shaft round
22:32 SolarNRG what do you think?
22:32 SolarNRG How hard would it be to engineer?
22:34 orlok heh hi SolarNRG
22:34 orlok SolarNRG: Oh - soething you may want to consider - cheap newtonian telescopes on ebay
22:37 SolarNRG Why would I consider these?
22:37 SolarNRG What use would they be?
22:38 SolarNRG I guess they can track the sky
22:38 SolarNRG But can they handle the weight and winds of a big mirrored skydish?
22:47 orlok SolarNRG: newtonian telescope.. not a tripod
22:48 SolarNRG Why do I need a scope though?
22:48 SolarNRG Is it to concentrate light energy like a poundshop magnifying glass?
22:48 orlok SolarNRG: Look at what a newtonian telescope is
22:48 SolarNRG I know
22:48 SolarNRG Its a big tube with a lens
22:48 SolarNRG And the motorised ones keep it locked onto a star
22:49 SolarNRG Or you could use it to lock onto the sun
22:49 orlok No...
22:49 orlok newtonian telescope
22:49 orlok and the rest of it is not a part of the telescope
22:49 orlok thats all the telescope mount
22:49 SolarNRG http://www.ebay.co.uk/itm/Sky-Watcher-EXPLORER-130M-Motorised-Newtonian-Reflector-Telescope-/140663816626?pt=UK_Photography_Telescopes&hash=item20c03781b2
22:49 SolarNRG that basically
22:50 SolarNRG ok explain to me what it does cos im, thick
22:50 orlok thats a newtonian reflector on an equatorial mount with a clock motor
22:50 SolarNRG ok
22:51 orlok meaning the mount can compensate for the earths rotation
22:51 orlok ignore the mount for the moment
22:51 SolarNRG ok
22:51 SolarNRG right
22:51 orlok understand how a newtonian telescope works yet?
22:51 SolarNRG its a tube with a load of mirrors that makes jupiter look big
22:51 orlok one mirror
22:51 SolarNRG one mirror!?
22:52 SolarNRG :o
22:52 SolarNRG is it curved?
22:52 orlok one highly polished curved mirror
22:52 orlok made to rather large amounts of light and reflect it to a focal point
22:52 SolarNRG Oh I see
22:52 SolarNRG So I make it face the sun
22:52 orlok people often get given crap ones and end up selling them cheap on ebay a year later
22:53 SolarNRG why are they crap?
22:53 SolarNRG they go out of sync?
22:53 SolarNRG or they melt
22:53 SolarNRG I mean what would happen if I made the newton telescope stare at the sun all day every day?
22:53 SolarNRG The eyepiece would be a dot of concentrated light energy
22:53 SolarNRG You wouldnt want to look through it
22:55 orlok SolarNRG: they are crap as the mounts are very annoying
22:55 SolarNRG So are you saying keep my existing mirror tiled skydish?
22:55 orlok they are also usually relativly small, 4" or so inches diameter instead of 8" or whatever
22:55 SolarNRG Or just use the telescope as a concentrator?
22:56 orlok y was thinking you could use the mirrors as cheap concentrators
22:56 SolarNRG Yeah but I can get the mirrors I need from the pound shop, cost me 4 quid and a bit of effort with the tile cutter
22:57 SolarNRG glue isnt expensive
22:57 SolarNRG and skydishes you get out the skip
22:57 SolarNRG i see what your saying but costwise it doesnt work out cheaper
22:57 SolarNRG After this project I want to make one with a giant fresnel lens
22:57 SolarNRG But again
22:57 orlok yeah, but if you want more pinpoint accuract and power of where the light is being focused
22:58 SolarNRG You might be right with the polished curved mirror
22:58 SolarNRG Could I make a really big newtonian telescope?
22:58 orlok the mirrors you are using will only reflect light
22:58 orlok no, not the way you are doing it, not usable
22:58 orlok but people make their own curved mirrors
22:58 orlok glass blanks, grind and polish, then get them plated
22:59 SolarNRG OK so I made a solar sinter that can 3d print glass from sand
22:59 SolarNRG then I use that cad design of a glass curve to be silver plated
22:59 SolarNRG then that should do what my skydish would but more efficiently
22:59 SolarNRG right?
22:59 orlok you wouldent be able to solar sinter it accuratly enough..
23:00 SolarNRG Are we talking electron beam here?
23:00 orlok anyway - i see cheap newtonian telescopes all the time, it was just an idea
23:00 SolarNRG Could I use a newtonian telescope as a solar sinter?
23:01 SolarNRG I mean my mirrored skydish is unsuitable because it reflects the light across not down
23:01 SolarNRG Markus Kayser did it with giant lenses