#robotics Logs

Jun 07 2014

01:16 GuShH https://www.youtube.com/watch?v=66c6IUD9Brc this is fucking awesome
02:17 rue_more ?
07:13 password2 how good is combo machine like this : http://www.gumtree.co.za/a-hand-tools/other/draaibank-r3-000/1001135175710910020780409
12:13 GuShH rue_more: 155KG of steel ordered
12:14 GuShH will you help me unload it?
12:14 GuShH (341.7lbs)
12:15 GuShH I think the reason the imperial system is still in use is rather simple... it makes everything sound bigger, to compensate for a lack of a certain something.
12:15 ShH nudges robotu
13:47 MrCurious if i have a 0.500" shaft and want to heat fit a gear to it... do i heat the gear and slip it on the shaft with the gear hot and shaft cold?
13:48 MrCurious and how much difference should there be in diamaters?
14:12 GuShH MrCurious: it should be an interference fit
14:12 GuShH MrCurious: you can make the shaft colder in the freezer
14:13 GuShH a press helps...
14:13 GuShH based on your expected tolerance the fit varies
14:13 MrCurious just checking if 12.7mm shaft vs 12mm gear would be right fit
14:13 GuShH and materials plus operating temperature range
14:13 GuShH nope
14:13 GuShH we're talking a few thou difference
14:14 MrCurious oh
14:14 GuShH such as... get rid of 0.0695mm on that shaft.
14:14 MrCurious then i may just have better results with some ciano acrilate
14:14 GuShH http://www.amesweb.info/InterferenceFit/InterferenceFit.aspx
14:14 GuShH that's quite good
14:14 MrCurious i can barely source 1/2" pushing for tighter tolerances would be prohibitive expensive
14:15 GuShH it has to be bigger
14:15 GuShH then turned down to size
14:15 GuShH usually precision ground by the end
14:15 GuShH on the races
14:15 GuShH (by hand that usually means emery cloth and micrometer)
14:15 MrCurious yeah, this project does not warrant that level of effort... super glue :)
14:15 GuShH not everyone has a lathe AND a toolpost grinder.
14:15 GuShH one day, one day.
14:16 MrCurious be easier to grind a key slot into the gear
14:16 GuShH ordered heaps of steel for monday-tuesday delivery so that would allow me to build more tooling
14:16 GuShH with keyed you use a slip fit, usually
14:16 GuShH still pretty damn close fit
14:16 GuShH that's what i had for the shaft I made
14:17 GuShH http://gushh.net/blog/wp-content/uploads/2014/02/DSCN5186f.jpg
14:17 GuShH that thing fits like a glove on the gear.
14:17 GuShH the hole is for the oil to get in between the parts.
14:18 GuShH SAE 1010 nothing fancy
14:18 GuShH I don't have the luxury to purchase fancy steels online
14:19 GuShH MrCurious: when it's a one off you just grind it to fit, trial and error, no need for a micrometer.
14:19 GuShH plus you would require inside mic or gage and not everyone has a set of those
14:20 ShH had a dream about an open lathe design made out of regular steel s
14:49 ratel ventilates the kitchen while heat-cleaning some cast iron lids that have a bunch of sticky residue on them. lots of thick smoke, which needs to be sent outs
14:50 thomas_r anyone around at this time of day?
14:50 MrCurious weekends are slim pickings
14:50 thomas_r aye, as if geeks have lives
14:52 thomas_r so, really basic questions though. i'm working on some basic computer vision using opencv before i start my first build. and i'm wondering, if i have an array of x/y coords of point P, how's the best way to calculate the velocity of P?
14:53 Hyratel what's your frame timing
14:53 Hyratel you can only measure speed with a difference
14:53 thomas_r atm 30fps
14:53 thomas_r so ~33ms
14:54 Hyratel if your target point P moves N px per frame, then you find the Field of View of the lens. then you take that and combine it with the distance to P from the lens, which you can then solve through Trig
14:56 GuShH Hyratel: may I suggest outdoors + solvent + gloves next time heh
14:57 GuShH or electrolysis, gets rid of grease and crud as well.
14:57 Hyratel don't have a suitable voltage source
14:57 GuShH any power supply
14:57 GuShH ATX, AT... old laptop charger
14:57 Hyratel mmm
14:57 GuShH battery charger
14:57 Hyratel I'd use an automotive charger but my biggest one is 6A
14:57 GuShH that's plenty enough
14:58 GuShH for that kind of part size
14:58 Hyratel and it's a Smart charger
14:58 GuShH not very smart
14:58 Hyratel errr, it is
14:58 GuShH as lead acid batteries self regulate heh
14:58 Hyratel it's a pretty sophisticated unit
14:58 GuShH you can have any voltage source and current will drop to a minimum as long as the battery reaches it's target cell voltage
14:58 ShH eyer
14:59 GuShH it looks that way, I doubt there's much else than a window comparator in the circuit the rest is just user gimmick
14:59 Hyratel hey, *I* didn't buy it. i got it used from the robotics team
14:59 GuShH if it's for lithium and such, then yeah it's a bit more advanced.
14:59 GuShH with usually custom ICs for the management
14:59 Hyratel mmmm, ok fine
15:00 ShH complains about the garage being too
15:00 Hyratel but the next block to 'lysis becomes container
15:00 GuShH plastic bucket
15:00 GuShH or gallon jug
15:00 GuShH for smaller parts
15:00 GuShH paint bucket...
15:00 Hyratel needs to fit a size 12 iron cookpot lid
15:00 GuShH eek
15:00 Hyratel which is ... 14? 15" across
15:00 Hyratel tolju
15:01 GuShH for copper I would have other suggestions
15:01 GuShH vinegar, salt, flour ... mixed into a paste, applied warm to the surface for 2-3 minutes, then swirled with a soft brush
15:01 GuShH gets you nice clean copper every time.
15:01 GuShH (not as dangerous as it sounds chemically speaking)
15:02 Hyratel it just barely fits flat in the kitchen sink
15:05 Hyratel so I'd probably have to specially source the container to 'lysis that thing
15:05 thomas_r GuShH, that mix sounds like it'd melt everything in sight!
15:11 GuShH thomas_r: just the copper oxides
15:12 GuShH quite frankly vinegar and lead is way more dangerous, as a common-household mixture
15:12 GuShH ....or chlorine and ammonia...
15:12 GuShH or.... better stop there
16:03 Hyratel GuShH, it seems I'm missing a sppol of bare steel wire I thought I had. crap.
16:03 Hyratel kindof need that to connect to the iron
16:06 Hyratel and I don't have washing soda
16:32 Hyratel aha
16:32 Hyratel brother found the wire. now I just need the washing soda
16:34 Hyratel GuShH, do you do much 'lytic cleaning of iron?
17:05 GuShH Hyratel: you can make washing soda if you have baking soda
17:05 Hyratel what's the process/difference in use?
17:06 GuShH Hyratel: last thing I did with iron was a hand vise from england which I couldn't positively identify (age wise) but early 1900s
17:06 GuShH basic redux
17:06 Hyratel redox?
17:07 GuShH ask in #chemistry for details :p
17:09 ShH and chemistry don't really
17:10 GuShH no emulsion possible either.
17:11 GuShH In reality I like chemistry I just don't like the idea of spending a lot of money in yet another hobby. so I only learn what I need, caveman style.
21:09 Hyratel1 GuShH, when seasoning cast iron, I heat it till it stops smelling funny
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