#robotics Logs

Mar 11 2014

02:20 Fiesta i have an urge to do the dumb thing
02:21 Fiesta to drive my steppers straight from the microcontroller, no driver circuitry
02:21 Fiesta i hear this is a bad idea
02:23 Fiesta they are really small steppers though
02:24 Hukka Sure, go for it
02:25 Fiesta i think their ISO size designation is: "Adorable"
02:25 Fiesta NEMA-Adorable
02:26 Fiesta have you done it?
02:26 Fiesta i'm trying to find info on ppl who have done it
02:27 Fiesta not really sure what search terms to use though, dunno what this is called
02:32 Fiesta www.ebay.com/itm/221343910653 such little things
02:37 Hukka "We do not have any info about it, pls make sure you can handle it before purchasing. thank you so mcuh! " Quite
02:37 Fiesta yeah :-/
02:38 Fiesta has a ton of different ones http://stores.ebay.com.au/Best-IC-store/_i.html?_nkw=stepper and doesn't have any info on any of them
02:38 Hukka But I'm sure they won't draw more than 20mA
02:40 GargantuaSauce i don't think it's unlikely that the inductive kickback from them will make the mcu latchup
02:40 Fiesta i want to drive as many as i can at once :)
02:41 Fiesta i might use a lot of small cheap arduinos though, to spread the load out.
02:41 Fiesta instead of one big mega
02:41 GargantuaSauce your idea has magic smoke written all over it
02:41 Fiesta yeah, but cheap magic smoke
02:42 Fiesta prolly best to test them once they arrive, see how much amperage they tend to pull.
02:42 Fiesta (these arduinos are only like $3 each)
02:44 Fiesta do you really think the inductive kickback even from these tiny things will be harmful GargantuaSauce?
02:44 GargantuaSauce potentially yes
02:45 GargantuaSauce MAYBE with external clamping diodes it will be ok but i dunno
02:45 Hukka But that's cheating
02:45 Hukka Has to be straight from micro (except it isn't... was arduino again)
02:45 Hukka I mean who would but capacitors when using a driver shield either
02:46 Hukka That's what the shield is for, right
02:46 Hukka *put
02:46 Fiesta i didn't think that was possible when working with this digital stuff. won't capacitors etc stuff up the signal?
02:47 Hukka Err, what?
02:47 Hukka I don't
02:47 Fiesta steppers
02:47 Hukka You don't even...
02:47 Hukka I give up
02:47 Fiesta <Hukka> I mean who would but capacitors when using a driver shield either
02:49 Fiesta your hyperbole is nice and all. but is that a yes or a no?
02:50 GargantuaSauce my answer is to do it properly with external circuitry
02:51 Fiesta that's your answer to everything
02:52 Fiesta sensible man
02:55 Fiesta to put it another way. i hear a lot of "don't do that you'll fry the chip", i'm sure you've all heard it too. Which is probably why we never do it. But has anyone here done it? maybe the result has more nuance, and one can be less careful than we have been if the dangers are properly navigated (instead of fleed from).
02:55 Fiesta so i guess no-one here has done it. mind you, channel is quiet atm
08:51 rue_house are you trying to drive steppers directly off an avr!?
17:55 ShH_ kicks robotustra_'s alien head to the gr
17:57 m_itx drops GuShH_'s lathe on his
18:04 GuShH_ Tom_itx: ouch!
18:04 GuShH_ Tom_itx: thoughts? http://mla-s2-p.mlstatic.com/fresadora-n-1-11272-MLA20041651456_022014-F.jpg
18:05 GuShH_ it's got the vertical head, but it doesn't have some of the cool things I'd like
18:05 GuShH_ it's not a real bridgeport, those are expensive here.
18:05 GuShH_ and yes it was made in argentina, back when we had industries and they were quite good (they still work fine)
18:06 GuShH_ if I add the cost of the vice, the rotary head with the tailstock... and collets, plus endmills and whatnot, it gets rather expensive. but only as expensive as one of the tiny chinese mills they resell around here.
18:06 GuShH_ and you can fit 3 of those on the table of this one.
18:07 Tom_itx one of the guys in linuxcnc has one quite similar
18:08 Tom_itx uses it for all sorts of things including a lathe
18:08 Tom_itx he's cnc'd his
18:09 Tom_itx https://plus.google.com/photos/108164504656404380542/albums/5901688686374813281
18:09 GuShH_ Tom_itx: of course he cnc'd his :p
18:10 GuShH_ I can make space if I get rid of the old safe the previous owner left behind, it's got the same footprint as that mill....
18:10 Tom_itx http://www.cnczone.com/forums/vertical-mill-lathe-project-log/109301-harrison-universal-miller-conversion.html
18:10 GuShH_ I think the size is "number 1"
18:10 GuShH_ smallest being number 0
18:10 GuShH_ I don't think I could house anything bigger
18:11 GuShH_ but surely it has to be sturdy for just about anything I'd do
18:11 Tom_itx yeah probably so
18:11 GuShH_ compared to the tiny china jobs
18:11 GuShH_ if they were cheaper I'd get one of the chinese mills, but they aren't here.
18:12 GuShH_ most of these cnc conversions are not cheap either!
18:12 Tom_itx you're probably better off with the one in the pic
18:12 GuShH_ some are plain hilarious, they spend more on the conversion than the machine is worth
18:12 Tom_itx yeah
18:12 Tom_itx i'm sure some do it just for a hobby
18:12 GuShH_ well most hobbies are expensive by definition
18:13 ShH_ doesn't mind surface rust, this mill is currently in use, the guy just wants to upgrade to a small, old cnc machine instead and is getting rid of some machines to pay fo
18:13 GuShH_ I asked him why don't you convert what you have, he said "I don't know how to do it, and if I hire someone it won't end up as good as I want it to be"
18:14 GuShH_ That's probably the reason why most conversions are made by the owners, otherwise it probably makes more sense to buy a real cnc
18:15 Tom_itx if you're in production you generally don't wanna take the time to do it
18:15 GuShH_ My only question is why is the vertical head blue http://mla-s2-p.mlstatic.com/fresadora-n-1-12299-MLA20057309883_032014-F.jpg probably from another machine or bought later on
18:15 GuShH_ why it -used to be- blue heh
18:16 GuShH_ rebuilding those things might not be a simple task, if the bearings / bushings are shot
18:16 GuShH_ 300mm travel I think on the bed
18:17 GuShH_ usable travel
18:17 GuShH_ I should go take a look at the machine first, see if it's what I want... the price is right for my pocket, but it's an investment nontheless.
18:17 GuShH_ and if I get it wrong, I'll end up crying myself to sleep for months.
18:17 Tom_itx yep
18:18 Tom_itx check it out for play etc
18:21 GuShH_ it ought to have some, it's very old
18:21 GuShH_ then again the new china ones also have play, right out of the factory.
18:21 GuShH_ at least in the backlash department.
18:21 Tom_itx some of those are pure shit
18:22 Tom_itx you can lap them
18:22 GuShH_ the other option was... http://mla-s2-p.mlstatic.com/fresadora-vertical-marca-ruizma-4399-MLA3534526760_122012-F.jpg but it's too expensive, and it's not a universal milling machine
18:22 Tom_itx scrape the ways etc to make them good again
18:22 GuShH_ but it does have the cool toys
18:22 GuShH_ the one on the back is massive by comparison
18:22 GuShH_ you can see they spray painted it for the picture
18:22 GuShH_ which is why I won't even bother going to see it.
18:23 GuShH_ paint doesn't mean anything to me, other than they're trying to dress it for some reason.
18:24 Tom_itx you should be showing these in the other channel
18:24 Tom_itx they're pretty sensible there really
18:27 GuShH_ oh?
18:27 GuShH_ they won't laugh at me for buying "toys" ?
18:28 Tom_itx hell no
18:28 Tom_itx they all get old junk to convert
18:28 Tom_itx or use
18:29 GuShH_ houses should come with a lathe and a mill by law.
18:29 Tom_itx ranges from wood routers to several ton size machines
18:29 Tom_itx plasma, laser etc
18:29 GuShH_ I'd be surprised if this one weighs over 350KG
18:30 GuShH_ but it probably does get close to half a ton
18:30 GuShH_ which begs the question, how to move it... using pipes on the ground to "roll it" is the only thing I can think of, but the floor is all uneven.
18:31 Tom_itx should still work ok
18:31 Tom_itx may take longer
18:31 GuShH_ the guy naturally has a guy that can transport it and drop it by the door heh
18:32 Tom_itx for how much?
18:32 GuShH_ no idea. he said "for a sensible fee"
18:32 GuShH_ I need to determine that.
18:32 Tom_itx you do
18:34 GuShH_ yes, small detail.
18:36 Tom_itx a mover i used alot moved my 80gal 5hp compressor over to my garage for free
18:38 ShH_ is as
18:38 GuShH_ Tom_itx: you and your magic friends
18:39 Tom_itx andy was the one that did that conversion
18:39 Tom_itx i actually met him once
18:40 Tom_itx he's in england
18:59 rue_more everyone paints equip when selling it
19:05 GuShH_ Tom_itx: did you have a cuppah with him?
19:05 ShH_ chuc
19:05 GuShH_ rue_more: most do, it gets my nerves.
19:05 GuShH_ ITS NOT A RESTORATION YOU ARE JUST HIDING THINGS
19:05 GuShH_ last thing you do is paint.
19:06 rue_more they want to make it look good for managers who aren't looking at details, they are just 'getting a machine'
19:06 GuShH_ get a part all cleaned up, new grease, fix whatever is wrong with it (hopefully before you put the new grease in, eh!) and THEN mask and paint.
19:06 GuShH_ I know I will restore whatever I buy
19:06 GuShH_ because... OCD.
19:10 Tom_itx he came over to the linuxcnc fest this last year
19:10 Tom_itx i stopped by for part of a day
19:11 Tom_itx met quite a few of the guys in the channel
19:13 rue_more ooo my next ebay arrival should be a reel of 2k resistors
19:15 ShH_ blinks at rue_
19:20 Faek They aren't all the same value are they?
19:21 Tom_itx i would hope so being on a reel
19:22 GuShH_ haha
19:22 GuShH_ they should be
19:23 ShH_ sighs and heads back to the "s
21:32 MrCurious those crazy germans invented pole dancing robots
21:33 MrCurious http://www.youtube.com/watch?v=wrBG8kIiMC0
21:51 GuShh_Lap2 MrCurious: what are you doing here? shouldn't you be watching Glee or something
21:51 MrCurious thats only popular in argentina
21:51 MrCurious its shunned here
21:52 GuShh_Lap2 it is popular?
21:52 GuShh_Lap2 I wouldn't know.
21:52 GuShh_Lap2 The fact that you know, worries me.
21:52 Shh_Lap2 turns his gaydar up t
21:55 robotustra_ salut
21:56 MrCurious who you aclling a salut....
21:56 MrCurious you horta
21:57 robotustra_ thinking about UPS with this battery http://www.ebay.com/itm/Lithium-Ion-Motorbike-Battery-Honda-Gyro-Canopy-Up-X-2000-Onwards-LIPO07B-/331103914344?pt=UK_Motorcycle_Parts_13&hash=item4d1754c968
22:31 rue_more do you need a light ups?
22:43 robotustra_ I need durable UPS
22:43 rue_more lead acid is more durable
22:43 robotustra_ LiPO does not degrade with the tile
22:43 robotustra_ time
22:43 robotustra_ I'm not sure
22:44 rue_more yea, in those conditions it wont last nearly as long as the lead
22:45 robotustra_ I need about 200 W of continious power for robot
22:45 robotustra_ at 24-60 V
22:46 GargantuaSauce lipos definitely do degrade with charge cycles
22:46 GargantuaSauce also any overdischarge = totally ruined
22:46 rue_more well if you need it as a robot you need it to be light
22:46 GargantuaSauce the only real reason to choose them over sealed lead acid is power density
22:46 GargantuaSauce yes
22:46 robotustra_ the problem is that UPS is usually doesn't discharge battery
22:47 rue_more if its a ups sitting on the floor, weight is not a factor
22:47 robotustra_ don't
22:47 GargantuaSauce i would definitely recommend lead acid
22:47 robotustra_ nowadays I don't have a lot of outage
22:47 robotustra_ like 1-2 per year
22:48 rue_more damn, how do I multiply fixed place numbers
22:48 robotustra_ LiPO is enough
22:48 GargantuaSauce you also don't want to keep lipos at 100% charge
22:48 robotustra_ lead acid degrade in 3 years
22:48 GargantuaSauce they degrade quite quickly if not kept at 70%
22:48 GargantuaSauce they are suitable for mobile devices
22:49 GargantuaSauce SLA is way way better for UPSes
22:49 robotustra_ if they are charged 100% they keep the charge very long time
22:49 GargantuaSauce rue_more: multiply them as integers, shift 2x the fixed point offset
22:49 robotustra_ I beleive in facts only
22:49 GargantuaSauce 1.00 -> 100, 100x100 = 10000 -> 1.0000
22:50 GargantuaSauce well then google it instead of asking our opinions
22:50 robotustra_ LiPo can be charged a year and does not dorp a garge
22:50 robotustra_ for this time led acid will loose the capacity
22:51 robotustra_ in 3 years led acid will die
22:52 rue_more your result is wrong
22:52 rue_more should be ... ah
22:52 robotustra_ I have 3 Lipos at home
22:52 robotustra_ they had being charged more that 1 year ago
22:52 GargantuaSauce rue_more: and be very careful about the input ranges of course
22:53 robotustra_ they are still show the same voltage
22:53 GargantuaSauce yes and instantaneous voltage is the ultimate and all-encompassing metric of a battery's performance
22:53 rue_more 3.14 * 2.0 314*200
22:53 GargantuaSauce bang on analysis dude
22:54 rue_more 62800
22:54 robotustra_ ok, I'll find a discharger
22:54 rue_more then shift two places
22:54 robotustra_ or make one
22:54 rue_more for 628
22:54 GargantuaSauce shift FOUR places
22:54 GargantuaSauce 2 + 2
22:54 GargantuaSauce 2 * 2
22:54 rue_more its decimal
22:54 robotustra_ I heed a DC power meeter as well
22:54 GargantuaSauce the base has nothing to do with it
22:55 GargantuaSauce my example was decimal or hex or whatever it doesn't matter at all
22:55 robotustra_ better if it will have rs232 interface
22:55 robotustra_ of rs485
22:56 robotustra_ or
22:56 GargantuaSauce rue_more: 314 = 3.14*100, 200 = 2.00*100, 62800 = 3.14*2.00*100*100
22:57 robotustra_ DC Power meeter with rs232
22:57 GargantuaSauce = 6.2800 * 100 * 100 = 6.2800 * 10000 blah blah i hope you get it at this point
22:58 GargantuaSauce also consider using soft floats, they aren't THAT slow
22:58 robotustra_ 3.14 100 * 314 =; 2.00 100 * 200 =;
22:58 GargantuaSauce (since this is just a ui thing)
23:00 GargantuaSauce rue_more: also i think gcc has builtin support for fixed point and it probably has architecture-specific optimizations
23:00 GargantuaSauce hell it looks like it has saturation math intrinsics
23:00 GargantuaSauce use those.
23:00 robotustra_ what are you doing guys?
23:01 GargantuaSauce actually i lied. looks like someone was working on it but the patches never made it into gcc
23:01 GargantuaSauce use a library instead
23:01 GargantuaSauce rolling your own fixedpoint without saturation is asking for trouble
23:02 GargantuaSauce http://sourceforge.net/projects/avrfix/
23:03 rue_more nonono
23:03 rue_more I'm using fixed point cause its easy to print
23:03 rue_more from current and voltage, I just need to calc wattage and maybe resistance
23:04 GargantuaSauce i don't see any reason in there not to use a decent solution
23:05 robotustra_ shit
23:05 GuShh_Lap2 Tom_itx: do these slip once they get past the threading point? http://mla-s1-p.mlstatic.com/roscador-porta-terrajas-universal-4175-MLA2619437104_042012-F.jpg how do they work? another view: http://mla-s1-p.mlstatic.com/roscador-porta-terrajas-universal-4166-MLA2619411892_042012-F.jpg
23:05 robotustra_ don't know where to start from
23:05 GuShh_Lap2 hopefully not by spinning on the morse taper...
23:05 robotustra_ either buy LiPo batteries or make a power meeter first
23:05 robotustra_ or make a charger for that
23:22 MrCurious yeah!
23:22 rue_more I wonder if its of use to have the power supply tell me the effective resistance of the load
23:23 GargantuaSauce i could see that being of use to napkin math
23:23 GargantuaSauce obviously it's less useful for anything nonlinear but still
23:24 rue_more I ahve it telling me the wattage
23:24 rue_more ... if I get this math right