#robotics Logs

Feb 16 2014

00:39 Jak_o_Shadows I have not bought steppers yet.
00:40 Jak_o_Shadows My torque calculations are somewhat lower than expected
00:43 shredder_ Anyone got a good quadruped robot using servo's?
00:50 shredder_ If u have send me a link at shredder@bshellz.net .. I want to build diy stuff..
01:06 Curious makes McKayla
03:16 Hukka Maybe I should send a lmgtfy.com link to shredder
12:29 MrCurious you should, but use a disposable email address, i suspect he is one to mail back lot
12:29 MrCurious s
13:30 bsilvereagle Hukka: lmddgtfy.net
13:39 MrCurious MSNBC is showing bill nye the science guy debating a politition on climate change
13:41 MrCurious we are still debating if climate change is real, while the chinese have already taken measures to remove the smog-appocolypse they were having
13:42 MrCurious can we agree to stop letting hillbillys get the mic when it comes to climate change
13:55 GuShH_ rue_house: the thread on your toolpost handle is M8 or M10?
13:55 GuShH_ I noticed it's the same as the belt tensioner
13:56 GuShH_ and the toolpost bolts
13:56 GuShH_ these lathes are mostly held together with M6, M8 and M10 it seems
13:56 rue_house M10
13:56 rue_house at the bottom
13:57 rue_house the top thread is smaller, prolyl M8
13:57 GuShH_ latest little "mod" I added two grub screws where the follow steady goes, so the threads will keep clean
13:57 rue_house ah, good idea
13:57 GuShH_ they were STUFFED, I had to chase the threads
13:57 GuShH_ the grub screws wouldn't turn
13:57 rue_house yea I was picking bits out of mine last week thinking about it
13:58 GuShH_ one less thing to worry about I say
13:58 GuShH_ now I need to figure out why the motor squeaks when it's off, must be the centrifugal switch inside
13:59 GuShH_ it really busts my balls they didn't use sealed motors
13:59 rue_house mine is closed
13:59 GuShH_ you know the blast proof ones, I forgot the rating
13:59 rue_house you have a dc?
13:59 GuShH_ but the fans catch shit
13:59 GuShH_ it's AC
13:59 rue_house k
14:00 GuShH_ I'm going to change it for a 3 phase 1 hp
14:01 GuShH_ soft start will also help extend the life of the gear train
14:02 rue_house I'm a bit worried
14:02 rue_house I dumped oil into the headstock oiler, and the oil that came out the bottom with BLACK with material
14:02 GuShH_ I just need to figure out what size motor I need, and that probably means taking the current one off and I hate that, takes quite some time to get it set right
14:02 rue_house according to the book, it uses a ball bearing, there is a LOT of junk comming out of it
14:02 GuShH_ hmm mine has two oilers for the heatstock (two bearings there obviously)
14:03 GuShH_ first time stuff came out was dark green
14:03 GuShH_ possibly the packing grease
14:03 rue_house this is black with shiny bits
14:03 GuShH_ I oil it every time I use it
14:03 GuShH_ that's bad
14:03 rue_house yea
14:03 GuShH_ I assume casting sand got in the bearings
14:03 GuShH_ and pickled them
14:03 GuShH_ but I'm a pessimistic asshole.
14:03 rue_house I dont think I have anything fatal to worry about, it looks like I can repalce the bearings down the road if it comes to it
14:04 rue_house I cant find any play yet
14:04 GuShH_ I do see metal dust regularly but that's just from the aluminum, it sticks on the chuck
14:04 GuShH_ even with sharp tools I get surprising amounts of this powder
14:04 rue_house do you have any sot23-5 on any of your pcb's labeled ADIU ?
14:04 GuShH_ rue_house: they didn't give you the pre-loading tools for the bearings, did they? because they never give those out
14:05 GuShH_ I would have to make them
14:05 GuShH_ come the day I need to adjust the tension on the bearings... or replace them
14:05 GuShH_ they are two hook type tools
14:06 GuShH_ as long as it offers a bit of resistance when turning freely (without a belt) it should be ok though, I'm not sure the manual states the procedure
14:07 GuShH_ I doubt they're ball bearings they should be roller bearings, tapered.
14:07 GuShH_ ok time to head back up on the roof... painting the wood sides
14:08 GuShH_ yesterday I went up with a small bucket of paint inside a bag, the bucket somehow managed to open itself and spill half the paint into the bag... not good.
14:09 GuShH_ I would use the spray gun but a) I don't have such long air hoses b) I need to get thick coats in and I don't want overspray (which would mean masking, complete waste of time IMO) ...
14:13 GuShH_ rue_house: any thoughts on how to get a structure to slowly go back up vertical, without accelerating rapidly and slamming -- as a common spring would do?
14:16 GuShH_ it's for reactive shooting targets,
14:33 rue_house spring with fluid damper
14:33 rue_house make a leaky cylinder with water in it, easy lathe project
14:37 GuShH_ meanwhile in russia http://www.armoryblog.com/firearms/hand-guns/homemade-glock-in-9x18-makarov/
14:37 GuShH_ robotustra_: robotustra!
14:37 GuShH_ rue_house: but it has to reset
14:38 GuShH_ rue_house: auto reset / reactive target, I don't want to dangle them from a cord
14:38 GuShH_ rue_house: look at the prices on these http://www.lvsteeltargets.com/
14:38 GuShH_ bastards
14:39 GuShH_ I might go for something like this design http://www.mrtargetonline.com/shop/mini-dueling-tree/
14:39 GuShH_ what a ripoff look at those price tags...
14:39 GuShH_ there's hardly 10 bucks in steel assuming you bought it brand new
14:40 ShH_ shakes
14:40 GuShH_ oh sure so they've got a cnc plasma cutter and that gives them the right to charge 280 fucking bucks...
14:40 GuShH_ FOR ANGLE IRON AND SOME THIN STEEL ROD
14:41 rue_house can it be wind-up?
14:42 GuShH_ rue_house: it's far away it has to work on it's own
14:42 GuShH_ using the energy transferred by the projectile
14:42 GuShH_ and or stored (therefor) on a spring or other mechanism
14:43 GuShH_ I'll probably copy that thing, it's for the backyard
14:43 GuShH_ but seriously 280 dollars... holy shit.
14:44 rue_house make it a challange, drinking bird
14:44 GuShH_ they claim it's AR500 steel, but there's no way it should cost over 80 bucks and that would be expensive IMO
14:44 GuShH_ rue_house: nothing that looks like an animal, just round or square targets.
14:45 GuShH_ they make an electric target that's basically a little buggy on a track, goes back and forth...
14:45 GuShH_ quite lame as it's always the same speed
14:46 GuShH_ http://www.mrtargetonline.com/shop/armored-dueling-tree/
14:46 GuShH_ 450 bucks!
14:47 GuShH_ that's just abuse.
15:14 MrCurious SURVEY: what do you put on fish and chips?
15:16 GeDaMo I prefer a white pudding and chips and I don't put anything on it
15:16 MrCurious no salt/vinegar?
15:16 GeDaMo Nope
15:16 MrCurious and what is white pudding? is that a sweet desert?
15:16 GeDaMo Oatmeal
15:17 GeDaMo https://en.wikipedia.org/wiki/White_pudding
15:17 bsilvereagle Sirachi or honey mustard
15:17 bsilvereagle if it's spicy breading then bbq sauce
15:17 MrCurious looks like klingon food
15:17 MrCurious thats true... Sirachi works everywhere
15:19 GargantuaSauce tartar sauce and sometimes ketchup
15:20 GargantuaSauce i havent tried sriracha but that sounds pretty good
15:20 MrCurious makes me think of tobasco sauce on egg-based breakfasts
15:20 GargantuaSauce frank's is the best with eggs
15:20 MrCurious which is nice and tasty
15:21 MrCurious everyone hungry now?
15:22 GargantuaSauce yes
15:23 MrCurious i bet that white pudding would be good with a spicy hot sauce
15:23 MrCurious imagine it is somewhat like saussage
15:26 MrCurious Prosecutor primises to retry dunn for first degree murder
15:26 MrCurious i think the prosecutor should have tried the first time...
18:37 ShH_ slaps MrCur
18:38 MrCurious cut that out
18:38 ShH_ slaps some
18:41 ilvereagle distracts everyone with http://www.twitch.tv/twitchplayspokemon
18:42 m_itx doesn't distract easily and refuses to c
18:49 ShH_ brutally stabs bsilvereagle for good mea
18:50 ilvereagle rocks the Darwin Danger Sh
21:21 robotustra_ http://www.youtube.com/watch?v=-Vg-BdXps50
21:30 KimLaroux http://www.youtube.com/watch?v=gcIwrdeP21s
21:36 rue_house huh
21:38 GargantuaSauce wasnt impressed till i saw it pushing the van
21:41 KimLaroux What impresses me is it's made around a snowmobile track, so it can be fitted to any snowmobile to transform it into an electric vehicule
22:07 rue_shop2 I think the tailstock is high by 15 thou
22:08 rue_shop2 which would explain things
22:10 rue_shop2 over the course of 60mm, the front back alignment is out by 2 thou
22:12 rue_shop2 horizontal within 1 thou over the 60mm
22:12 Tom_itx put a last word in the spindle and check it
22:12 Tom_itx with a dead center
22:12 rue_shop2 so, if the tailstock is high, do I shim the headstock?
22:12 Tom_itx make sure
22:12 rue_shop2 later I'll take a ground bar between two centers
22:13 rue_shop2 this was a bit of a quick test
22:13 rue_shop2 when I drill stuff, I'v noticed wrongness
22:13 Tom_itx it's china, what do you expect?
22:13 rue_shop2 wrongness
22:14 Tom_itx ppl lap the surfaces all the time on them to make things right
22:14 rue_shop2 I dont think shimming the headstock up 15 thou would be that hard
22:14 Tom_itx scraping the ways etc
22:15 Tom_itx how do you know the headstock is square to the table?
22:15 rue_shop2 the roommate moved out
22:15 Tom_itx is that good?
22:15 rue_shop2 I hvae the dial indicator on the chuck
22:15 rue_shop2 well, I'll see, he just left today
22:15 rue_shop2 so much garbage....
22:17 Tom_itx http://www.travers.com/horizontal-dial-test-indicator?Category=UserSearch=axial||UserSearch=block%20id%2082638%20and%20class%20level3%20id%20298988
22:17 Tom_itx something like that
22:18 rue_shop2 msxml3.dll error '80072efe'
22:19 rue_shop2 I think, to sense current on this supply, I'm gonna take some of the isaolated dc-dc Ihave, run a supply above the + output, give me a constant current line down to ground for the current sense
22:19 rue_shop2 sensing current on this supply is harder than i thought
22:19 rue_shop2 mainly having to bring everything back to ground for the microcontroller
22:31 Celelibi Is there a formula that would give me the torque I need in order to erect a 4 wheel robot into an inverted pendulum state?
22:40 GargantuaSauce i think the dynamics involved are a little too complicated to boil down into a single formula for the maximum required torque
22:41 GargantuaSauce start by pretending the wheels are fixed to the ground i guess
22:43 GargantuaSauce and then assuming the centre of mass is directly between the two pairs of wheels, the required torque is the half the distance between the wheels times the mass of the robot
22:43 GargantuaSauce ish
22:45 Celelibi Divided by the radius of the wheels, maybe?
22:45 GargantuaSauce doubtful
22:46 Celelibi Don't you think the radius of the wheel is an important factor?
22:46 GargantuaSauce that and about 10 other things
22:46 Celelibi With a size 0, I need an infinite force.
22:46 GargantuaSauce traction alone is a huge factor and very difficult to model effectively
22:48 Celelibi Maybe I could try to simplify the problem by wondering what should be the speed of the robot if I could fix its front wheel on the ground instantly.
22:50 Celelibi Yes, its exactly what you said. Except now I picture an instant stop, instead of an instant motion. :p
22:51 GargantuaSauce i mean pretending the wheel is not a wheel but an anchor
22:51 GargantuaSauce this will give you a lower bound
22:52 GargantuaSauce considering only the torque the motor needs to lift the front wheels, without any forward acceleration
22:55 GargantuaSauce in reality the requirement will be much higher but again it's a start
22:57 Celelibi I'm starting to picture triangles.
22:57 Celelibi One point is the center of mass, another point is the ground+wheel contact point.
22:58 GargantuaSauce yup
22:58 Celelibi The third point is defined by horizontal and vertical lines.
22:58 GargantuaSauce well, the axle of the motor works too
22:58 Celelibi When the sum of the initial force + gravity is colinear with the hypotenus of the triangle, I can start to lift.
22:59 Celelibi No, not the axle of the motors. It won't work.
22:59 Celelibi With wheels of size 0, I can't lift anything.
23:06 zhanx Hi
23:15 GargantuaSauce also Fiesta_ if you pretend the robot is free only to pivot about the wheel's axis, and can only exert torque into the wheel in order to counteract gravity and rotate itself by newton's third law
23:15 GargantuaSauce i think that'd be an upper bound
23:15 GargantuaSauce bluh i worded that poorly
23:16 GargantuaSauce (disregarding traction entirely)
23:23 GargantuaSauce i wanna try doing this now :x
23:23 GargantuaSauce shit's complicated
23:59 Fiesta wait was someone talking to me?