#robotics Logs

Jul 26 2015

00:23 Mushrooshi aaaaand omg this sounds nice
00:23 Mushrooshi https://vine.co/v/egpIQhm07DZ
01:04 fleshtheworld what kind of robotics you guys make / working on adn whut four
01:05 fleshtheworld be back
01:23 ace4016 world conquering robots, medical bots, lawn care bots, bots just to learn robotics
01:23 ace4016 some are hobbyist, some are professionals
01:23 ace4016 some are something inbetween
08:13 hans http://search-that-site.herokuapp.com
10:50 veverak silent here
10:50 veverak :)
10:56 ace4016 depends on the time of day and the day of the week
12:38 rue_bed so, at 4am, there was a huge rainstorm
12:39 rue_bed I'll need to go see whats floated away
17:01 veverak e3d
17:01 veverak made 3d printer
17:01 veverak so I opened it
17:01 veverak and
17:01 veverak god damn it I lvoe that thing
20:47 codepython777 anyone here?
20:47 Anniepoo 8cD
20:47 codepython777 Hi Anniepoo
20:47 codepython777 what are you working on?
20:48 Anniepoo work work for my company.
20:48 Anniepoo =8c)
20:50 codepython777 what kind of work?
20:51 Anniepoo coding SWI-Prolog
20:51 codepython777 swi?
20:56 codepython777 Anniepoo: what kind of robotics are you into? Coding in prolog?
20:56 Anniepoo we're starting a Manufacturing-as-a-service company
20:58 Anniepoo and yes, coding in Prolog
20:58 Anniepoo 8cD
20:58 Anniepoo =8cO
20:59 Anniepoo faced with a problem too complex for conventional solutions?
20:59 codepython777 Anniepoo: which country?
20:59 Anniepoo :CO Use a 28 year old codebase on a 40+ year old language!
20:59 Anniepoo USA
21:00 codepython777 Anniepoo: do you have a website yet?
21:01 Anniepoo http://www.theelginworks.com/
21:01 Anniepoo the Maas part is new - we're part of The Elgin Work's incubator program
21:02 Anniepoo Comin' atcha from tiny Elgin, Oregon, home to a crap ton of machinery
21:02 Anniepoo what do you do?
21:03 codepython777 Anniepoo: do you cut aluminium?
21:04 codepython777 Anniepoo: I'm trying to build a 4 wheeled truck - and keep having odd requirements.
21:04 codepython777 Anniepoo: how much was your tormach?
21:04 codepython777 which one did you get?
21:05 Anniepoo do you have drawings of your part?
21:05 Anniepoo and how big is it?
21:05 Anniepoo and what sort of aluminum?
21:05 orlock ahh your website is annoying
21:05 codepython777 Anniepoo: 16" x 16" x 16" box
21:06 Anniepoo garsh - it is?
21:06 orlock the cursor changes to a text select on the side menu
21:06 orlock yet its clickable
21:06 Anniepoo ah, ok, we'll fix that
21:06 orlock its not horrible
21:06 orlock it just doesnt act the same as everything else
21:06 Anniepoo (website made in about 45 mins)
21:07 codepython777 Anniepoo: which tormach did you get? how much did you guys pay?
21:07 Anniepoo code, not sure our envelope's big enough to cut that
21:07 orlock you can vac. cast pewter?
21:07 orlock did i read that right?
21:07 Anniepoo my partner's more the machinist
21:08 Anniepoo yes, we can vac cast pewter
21:08 orlock heh cool
21:08 orlock ex-job, one of their clients was a printer who did labels
21:08 Anniepoo not really part of us, but there's an artisanal brass foundry nearby
21:08 orlock they re-purposed one of the old old label presses to emboss thin pewter/alloy sheets
21:08 orlock for "classy" bottle labels
21:09 Anniepoo makes sense
21:09 Anniepoo when I was a kid we did this craft project - came with a thjn sheet of copper, a plastic bas relief backing, and a sharpened dowel
21:09 orlock "holes in the ground"
21:09 orlock heh
21:10 Anniepoo yah, that was sorta tongue in cheek
21:10 codepython777 Anniepoo: which tormach did you get?
21:10 Anniepoo we're sorta an accidental business - we're both software engineers, we both had some industrial machinery, we decided to merge our toys
21:10 Anniepoo hang on code, lemme run down and read the number off it
21:11 Anniepoo 1100
21:11 Anniepoo was around 15K I think
21:11 Anniepoo the expensive part's not the base machine, it's all the stuff that goes with it.
21:12 codepython777 Anniepoo: what is the running cost once you have the machine?
21:12 codepython777 like buying aluminium cubes to cut? bits ? etc? is it reliable?
21:13 codepython777 Anniepoo: where did you buy the tormach from? which website?
21:14 Anniepoo like installing electrical, various tooling, workholding, etc.
21:14 Anniepoo I don't know
21:14 Anniepoo the tormach came with partner
21:14 codepython777 Anniepoo: you are in CO?
21:14 Anniepoo Oregon
21:15 codepython777 cool
21:15 Anniepoo tiny town in remote east Oregon
21:15 Anniepoo ~8c) The obvious place to go to create a revolution in global manufacturing
21:16 Anniepoo =8cO
21:16 codepython777 Anniepoo: Very nice, and good luck.
21:16 Anniepoo thanks
21:16 codepython777 Anniepoo: I'd say move on from prolog to something newer :)
21:16 Anniepoo nope nope nope
21:16 codepython777 python perhaps ? ;)
21:16 Anniepoo moved on from Java to Clojure, then from Clojure to Prolog
21:16 codepython777 wow, thats quite a move
21:17 Anniepoo Prolog's the new thing
21:17 codepython777 Anniepoo: what software are you writing? if people give you their CAD design, and you print it - where is the software?
21:17 Anniepoo in the browser 8cD
21:18 Anniepoo in my fingers mostly, at hte moment - I'm coding now
21:18 codepython777 8cD?
21:18 codepython777 browser?
21:18 codepython777 explain please
21:18 Anniepoo old fashioned smiley
21:19 Anniepoo a browser, or 'user agent' is a program that displays, or 'renders' pages from the world wide web.
21:19 codepython777 Anniepoo: If I have a 3d cad part which needs to be cut from 1" x 1" x 1" alumnium cube - how much cost am i looking at with the 1100 to do so?
21:20 Anniepoo dunno.
21:20 Anniepoo email kevin@theelginworks.com with the file.
21:21 codepython777 Anniepoo: I dont have a file. Here is my problem. I'm looking to attach a motor to a wheel. The wheel has a cylindrical hole. The motor is a dc motor with a shaft. is there something i can do to attach the wheel reliably?
21:21 Anniepoo is it slipping now?
21:22 codepython777 Anniepoo: I've not put one. And it will slip , i am sure if i do it naively
21:22 codepython777 Anniepoo: or perhaps you know where to get good wheels ? I need a 8" that can do both roads and off road
21:23 Anniepoo put the motor shaft on a good flat anvil and give it a few whacks with a large hammer? That should distort it enough to be a pressure fit on the wheel.
21:23 Anniepoo if the wheel's plastic that should work.
21:23 Anniepoo yes, visit a store that sells RC cars
21:23 Anniepoo they'll be able to advise you
21:23 Anniepoo and might have a more elegant solution to your hub problem
21:24 codepython777 Anniepoo: I need at least 25lb weight on the wheel - most RC Car shops say "What?"
21:24 Anniepoo oh, sorry, was imagining something smaller
21:24 Anniepoo ok - you need a small 'real' wheel
21:24 Anniepoo 8" diameter?
21:25 codepython777 yes
21:25 codepython777 Anniepoo: Maybe you can cut me some with your Tormach ;) Then put a pneumatic wheel on top of the alu/steel cut :)
21:26 Anniepoo http://www.harborfreight.com/material-handling/pneumatic-tires/10-in-pneumatic-tire-with-white-hub-62409.html
21:26 Anniepoo sure, but us doing them custom would be pricy
21:26 Anniepoo there's 10" tires
21:26 codepython777 wow, you are fast
21:26 codepython777 It took me an hour to find that one - it has a round hole
21:27 Anniepoo 8" pneumatic tires
21:27 Anniepoo well, basically you want wheelbarrow wheels
21:27 Anniepoo http://www.amazon.com/Marathon-Industries-20001-Pneumatic-Wheelbarrow/dp/B0000AX2DK/ref=sr_1_2?ie=UTF8&qid=1437962661&sr=8-2&keywords=8%22+pneumatic+tires
21:27 codepython777 Anniepoo: the problem with that one - is slippage
21:28 codepython777 Anniepoo: same problem
21:28 Anniepoo oops, sorry, that's wrong size
21:28 codepython777 Anniepoo: I just had those wheels in my hands - a few minutes ago
21:28 codepython777 Anniepoo: the problem is the cylindrical hole
21:28 Anniepoo ok, well, I'd put the wheel on the shaft and head to your local welding shop
21:28 Anniepoo 8cD
21:29 codepython777 never thought about welding
21:29 Anniepoo just have them weld the bearing solid
21:29 codepython777 but i would rather have something simple
21:29 Anniepoo hit that sucker with a MIG and it wont slip 8cD
21:29 Anniepoo ok, for something less permanent, take a file
21:30 codepython777 Anniepoo: I want a long term solution - something simple. I need to build 100 of these...
21:30 Anniepoo file a small notch in the barrel part of the hub
21:30 Anniepoo insert axle, drill a hole all the way through
21:31 Anniepoo stick in a bolt, put a locknut on the other side
21:31 codepython777 Anniepoo: arent there better wheels for such things?
21:31 Anniepoo these seem like perfectly good small pneumatic wheels
21:32 Anniepoo if you're starting a robot factory at some point you will indeed need some machine tools
21:32 Anniepoo but these are truck dolly tires
21:33 codepython777 Anniepoo: the only problem is putting the shaft in these wheels - these wheels are not designed for that. But I was hoping there are wheels like that?
21:33 Anniepoo buy a harboir freight hand truck jsut to get the wheels and hubs
21:34 Anniepoo well, you're missing a piece
21:34 Anniepoo the hub
21:34 Anniepoo http://www.harborfreight.com/heavy-duty-hand-truck-95061.html
21:34 Anniepoo buy one of those
21:34 Anniepoo you now have two wheels on an axle. they're live on the axle
21:34 Anniepoo they have hubs
21:34 Anniepoo you want them dead on the axle
21:34 codepython777 dont think they have hubs - the wheels slip on the cylinders
21:35 Anniepoo so weld them
21:35 Anniepoo this is getting repetitive
21:35 codepython777 I do not want to go the welding route
21:36 codepython777 machining / cutting is fine
21:36 Anniepoo fine - find a set of wheels with hubs.
21:36 Anniepoo drill a hole radially in the side and tap it
21:36 Anniepoo put in a set screw
21:37 Anniepoo you probably need a couple of them for this much torque
21:37 Anniepoo or you might want to grind a flat on the shaft
21:38 codepython777 Anniepoo: looking for wheels with hubs: http://www.mfgsupply.com/gomini/gominihubs/53-681.html
21:38 Anniepoo ok, there you go
21:39 Anniepoo nice hub, it's locked on the axle with a key
21:39 Anniepoo does your shaft have a keyway?
21:39 codepython777 Anniepoo: nope. I just have a DC motor shaft for now. Need to find what all do i need.
21:40 Anniepoo (guess I reversed 'live' and 'dead' earlier - was thinking of lathe centers)
21:40 Anniepoo well, this hub was designed to lock a shaft to itself using a key
21:40 codepython777 I've a 6mm D-shaft on the motor
21:41 Anniepoo then you'll need to machine an adapter
21:41 Anniepoo (and, I gotta say, are you sure you have enough motor for this?
21:42 codepython777 Anniepoo: Rated Load: 4.5 kgf-cm - any good ? I've 4 of them
21:42 Anniepoo do the math
21:43 Anniepoo on a level surface, how much pull do you want the robot to have?
21:43 codepython777 Anniepoo: 20kg preferably
21:43 Anniepoo torque / radius = force
21:44 Anniepoo 8" = 20cm = 10cm radius
21:44 Anniepoo 0.45 kg pull x 4 motors
21:45 Anniepoo btw, to get 20kg tractive effort you'll need a vehicle weight of 100-200 kilos
21:46 Anniepoo http://www.mfgsupply.com/gomini/gominihubs/az2275.html
21:46 Anniepoo take the zerk out and put in a set screw
21:47 codepython777 Anniepoo: so if you have 4 such motors, how do you calculate how much weight it can carry at a 15 degree uphill?
21:48 Anniepoo figure out how much it'd take to push the thing up the hill
21:48 Anniepoo vehicle_weight * sin(15 deg)
21:48 Anniepoo subtract that from your tractive effort
21:49 codepython777 20*sin(15) = 13
21:49 Anniepoo your vehicle only ways 20 kils?
21:49 Anniepoo ok,
21:49 codepython777 yes
21:50 Anniepoo http://hpwizard.com/tire-friction-coefficient.html
21:51 Anniepoo well, they're more optimistic than me
21:51 Anniepoo they give friction coeff of 0.75
21:52 Anniepoo but that's dry asphalt
21:52 Anniepoo what's the surface of this hill?
21:52 codepython777 grass
21:52 Anniepoo thats bad
21:53 Anniepoo wet grass - they give 0.1 for ice, lets use 0.2
21:54 Anniepoo 20 kg vehicle * cos(15 deg) * CoF
21:54 Anniepoo CoF = 0.2
21:54 codepython777 k
21:55 Anniepoo that's the max tractive effort you can exert on the ground with the tires
21:55 Anniepoo you need 13 just to raise the vehicle
21:56 codepython777 how much do those motors give me? what max total weight can i move over a 15degree incline?
21:56 Anniepoo 8cD dude or dudette, you need to learn some high school physics
21:57 Anniepoo and something about machining
21:57 Anniepoo you can't participate in a field without knowing the fundamentals of that field
21:57 Anniepoo even if they're not the 'cool part'
21:58 codepython777 Anniepoo: Agreed :)
21:58 Anniepoo you might as well just have use design and build your robot altogether
21:59 Anniepoo so, I'm sure there's a million sites on web that will explain the physics stuff - these are standard high school physics problems
21:59 Anniepoo the calculator I posted will give you the coefficient of friction you need
21:59 Anniepoo remember that the robot advances by pushing on the ground
22:01 Anniepoo you said you were making 25 of these robots?
22:01 Anniepoo (100 tires)
22:01 Anniepoo if so, is this a hobby activity? If not, the 'have us make it' might make sense
22:02 codepython777 Anniepoo: i had once done this calculation - now cant find it
22:02 Anniepoo additional life lesson: keep engineering calculations in a safe place
22:03 Anniepoo recommended viewing for you: watch the episode 'spider' from the tom hanks series 'from the earth to the moon'
22:03 Anniepoo "Mr Kelly, I'm sorry"
22:03 Anniepoo 8cD
22:08 codepython777 Anniepoo: http://www.robotshop.com/blog/en/files/torq.jpg - To move a 5kg payload with 1 motor - I need much more than 4.5kgf-cm?
22:09 Anniepoo how fast?
22:09 codepython777 M= 5kg, a = 0
22:09 Anniepoo seriously, you can't work these problems without understanding the basic physics
22:09 codepython777 R = 10, N=1?
22:10 Anniepoo at suborbital velocities? no, your little electric motor won't get your robot into orbit
22:10 codepython777 Anniepoo: 1 m/sec
22:10 Anniepoo seriously, I'm not doing more of this for you.
22:10 codepython777 k , thanks. :)
22:10 Anniepoo go make some calculations for yourself, and post them, and then I or somebody on here will be glad to help
22:11 Anniepoo but you're using a very bad anti-skill learned in school
22:11 Anniepoo 'get somebody else to do it for me'
22:14 Anniepoo the problem with doing that is that it doesn't get you anywhere.
22:15 Anniepoo tomorrow you want to pull a trailer with your robot, and you're lost how to do it
22:15 Anniepoo There's a time and place for hiring people - I'm working on a web site, and my choices are hire a professional web designer to make it look nice, or try to do it myself
22:16 Anniepoo the do it myself will make it look like the elgin works site
22:16 Anniepoo and i'm unlikely to improve to professional level visual design skills any time soon
22:17 Anniepoo but my web designer will be a smidge better web designer for having done my site
22:17 Anniepoo that's ok, and I'm happy to pay her bill
22:17 codepython777 Anniepoo: did you pay a designer to make that site?
22:18 Anniepoo no
22:18 Anniepoo I made the Elgin Works site, in not very long
22:18 Anniepoo I'm a software engineer, but not really a 'web dev', but I'm certainly not a visual designer
22:18 Anniepoo or an information designer
22:19 Anniepoo the elgin works site does it's job without a nice design
22:19 codepython777 Anniepoo: thats cool. indeed it does
22:19 Anniepoo and we needed the $500 for other things
22:21 codepython777 Anniepoo: Seems like i should be able to carry a 20kg payload with those motors - assuming 50% efficiency, 1m/s speed/acceleration.
22:22 codepython777 incline = 15 degrees
22:22 Anniepoo show calculations
22:22 Anniepoo not guessing
22:22 codepython777 found one mistake