#robotics Logs

Feb 14 2017

02:51 AM deshipu: z64555: first marry, then sue
02:53 AM deshipu: veverak: https://www.youtube.com/watch?v=keb0B11zj5g
03:13 AM veverak: nice
03:14 AM deshipu: shame it only works with the new one
04:39 AM rue_bed: do I have to voluntaqrrily stop thinking about things to get to sleep?
06:41 AM mun: hi
06:41 AM mun: i'm trying to mesh two plastic gears. does anyone know if there's a way to determine the centres of the gears?
06:41 AM mun: how far in should the teeth mesh?
06:56 AM Jak_o_Shadows: Hmmm.
06:57 AM Jak_o_Shadows: I might be able to work it out for real gears, but plastic ones probably have different teeth profiles.
06:57 AM Jak_o_Shadows: You could just pretend i'ts 2/3 in?
07:05 AM mun: Jak_o_Shadows, these are 0.5 modules
07:05 AM mun: so perhaps i could use this as reference? http://www.metrication.com/engineering/gears.html
07:05 AM mun: but then how much should the teeth mesh?
07:07 AM Jak_o_Shadows: They mesh up to the dedenumdun line maybe?
07:07 AM Jak_o_Shadows: wait.
07:07 AM Jak_o_Shadows: No.
07:07 AM Jak_o_Shadows: Pitch circle is pitch circle.
07:08 AM Jak_o_Shadows: The distance between two geras will be the sum of their pitch circles.
07:08 AM Jak_o_Shadows: What the pitch circle is, if you don't have a gear with specs though...
07:09 AM mun: Jak_o_Shadows, wouldn't that mean the teeth of one gear will touch the bottom of the dedendum?
07:10 AM mun: Jak_o_Shadows, but is the pitch circle based on the gear's module?
07:14 AM Jak_o_Shadows: Pretty sure nope.
07:14 AM Jak_o_Shadows: Also, yes, that page you linked does say PCD = N*MOD
07:15 AM mun: Jak_o_Shadows, but if C = (PCD(a) + PCD(b))/2 then the teeth would touch the base of the dedendum, right
07:15 AM mun: which probably isn't desirable
07:15 AM Jak_o_Shadows: I don't believe they quite tought
07:15 AM Jak_o_Shadows: touch
07:16 AM Jak_o_Shadows: the dednum and AD is not symmetrical about the PCD
07:16 AM Jak_o_Shadows: anyway
07:16 AM Jak_o_Shadows: goodluck
07:16 AM Jak_o_Shadows: Ask me tomorrow
09:29 AM rue_house: I was going to write a program to make gears, but
09:41 AM rue_house: http://hessmer.org/gears/InvoluteSpurGearBuilder.html
11:33 AM Snert_: what is an "involute" gear
11:41 AM deshipu: Snert_: https://en.wikipedia.org/wiki/Involute_gear
11:44 AM Snert_: thx. So it pertains to the path traveled of the contact point twixt the gears
11:45 AM Snert_: I figgered it to be something else.
12:10 PM robopal: hi
01:46 PM anniepoo: involutes - it's a handy thing to know about.
01:47 PM Snert_: I still don't see how the word "involute" applies in this case.
01:47 PM Snert_: be that as it may it still kinda makes sense.
01:48 PM anniepoo: the curve that forms the face of the gear is an involute spiral
01:48 PM anniepoo: this shape is important because two involutes can roll against each other without sliding
01:49 PM anniepoo: if the gears rotate at constant velocity.
01:49 PM Snert_: must be my limited knowledge of the use of the word involute.
01:49 PM Snert_: to me it means never changes.
01:49 PM anniepoo: well, an involute is a curve
01:50 PM anniepoo: you can make one by winding a string around a can, putting pencil in end of string, then unwinding
01:50 PM anniepoo: are you confusing the word 'invariant'?
01:50 PM Snert_: ok. so great....one has created an involute what? Piece of string in a straight line?
01:51 PM anniepoo: no, it's a spirally looking curve
01:51 PM anniepoo: keep the string tight, draw with pencil
01:51 PM anniepoo: eg if you just put a tack in one end of string, you'd get circle
01:52 PM anniepoo: http://mathworld.wolfram.com/Involute.html
01:55 PM Snert_: what part about that diagram never changes in the "involute" sense of the word.
01:55 PM anniepoo: what does change have to do with it?
01:56 PM anniepoo: what do you think the word 'involute' means?
01:56 PM Snert_: oic... involate as opposed to involute.
01:56 PM anniepoo: inviolate - cannot or is not violated
01:57 PM anniepoo: the speed of light is an inviolate limit
01:57 PM anniepoo: invariant - without varying
01:58 PM anniepoo: "the sum of money and free time is an invariant" - when you have a good job you have no time for robots, when you don't you have no money for robots
01:59 PM anniepoo: involute - a curve made with the string and can thing
02:00 PM anniepoo: if you're hung up on the 'in-' prefix, it's the inverse of 'evolute', which is a math thing you can read about on wolfram if you're into such things
02:00 PM deshipu: I think that's not strictly true
02:00 PM deshipu: about free time and job
02:00 PM anniepoo: yes, I'd agree, I was trying to articulate what 'invariant' meant
02:01 PM anniepoo: without bringing in gas dynamics or something
02:01 PM deshipu: doesn the "volute" basically mean "wrapping"?
02:01 PM anniepoo: yes, think so
02:01 PM anniepoo: not sure
02:01 PM deshipu: outline
02:01 PM deshipu: close enough
02:02 PM anniepoo: apparently there's a pair of geometric constructs, the evolute and the involute
02:02 PM anniepoo: but I'm getting this off skimming the wolfram page
02:02 PM deshipu: Latin voluta, from feminine of volutus, past participle of volvere to roll
02:02 PM anniepoo: http://mathworld.wolfram.com/Involute.html
02:02 PM anniepoo: http://mathworld.wolfram.com/Evolute.html
02:03 PM deshipu: ewolwenta and ewoluta
02:03 PM * anniepoo passes deshipu a cinnamon roll
02:03 PM Snert_: involate as opposed to involute.
02:03 PM deshipu: inviolate
02:03 PM Snert_: same thing.
02:03 PM Snert_: close enuff.
02:04 PM deshipu: would just "advanced differential algebra concept" be enough of an explanation for you? :D
02:04 PM Snert_: nope.
02:12 PM anniepoo: 8cD
02:13 PM anniepoo: ps - you can entertain small children with involute curves.
02:13 PM Snert_: spirograph was a favorite, 4sure
02:13 PM anniepoo: 8cD
02:14 PM anniepoo: also, tie them to a grain silo with a length of rope.
02:14 PM anniepoo: they'll describe an involute
02:14 PM anniepoo: 8cD
04:11 PM synja: anniepoo, what does 8cD mean??
04:15 PM anniepoo: it's my smiley
04:15 PM anniepoo: turn head left
04:16 PM synja: why not :) xD :} ??
04:16 PM synja: it doesn't draw as much attention to your large nose
04:36 PM deshipu: it's thre scoops of ice cream in a bowl
04:43 PM synja: so, after internet explorer crashed, it completely wiped out my entire partition
04:44 PM synja: how do you like that
04:44 PM deshipu: what did you expect from windows?
04:44 PM synja: that's why i only use it for gaming :P
04:44 PM deshipu: you agreed to the EULA
04:44 PM deshipu: yuo can ask Microsoft, they probably have a backup of your data
04:44 PM synja: it's going to be a bitch to reinstall/download everything
04:44 PM synja: lol i'd still have to download it all back
04:44 PM synja: i don't have any data on there but gaming
04:44 PM synja: i don't trust them
04:45 PM synja: this is partly why
04:45 PM deshipu: I have no idea what "gaming" data is and how it is different from other personal data
04:46 PM synja: it means the only things i downloaded for it are drivers, combat arms installer... that's it
04:46 PM synja: that's the only thing on there i've changed from the original install
04:46 PM synja: i'm on bsd from the machine i'm talking to, to give you a hint
04:47 PM deshipu: free bsd or open bsd?
04:47 PM synja: free. security isn't an issue on this box
04:48 PM deshipu: ha
04:48 PM synja: looks like it might not have been MS fault after all
04:48 PM synja: fked up HDD
04:48 PM synja: probably didn't help i interchange them 8+ times a day
04:49 PM * synja heavy sigh
04:49 PM synja: oh well. i'm down to my last 2 HDDs i can spare
04:50 PM deshipu: gut them for steppers ;)
04:52 PM synja: or smash them for disappointing me
05:12 PM mulvane_ is now known as mulvane
05:12 PM z64556 is now known as z64555
05:12 PM tumdedum_ is now known as tumdedum
05:21 PM Tom_itx is now known as Tom_L
07:50 PM malcom2073_ is now known as malcom2073
07:53 PM rue_house: hahah wholy freaking hell
07:53 PM rue_house: I posted some things on thingiverse, and my hits went balastic