#robotics Logs
Oct 16 2017
#robotics Calendar
08:24 AM edmoore: what is the current state of the art in lidar's in the sort of <3k bracket? for mostly indoor robotics. Is it still those hokuyo units?
09:02 AM rue_bed: none
09:03 AM rue_bed: no progress expected for about 3 years
09:04 AM rue_bed: evilroot, your in vancouver?
09:06 AM edmoore: rue_bed: oh well then
09:06 AM edmoore: why three years, specifically?
09:24 AM rue_mohr: time to market
09:28 AM rue_mohr: same as if you had asked about accelerometers in 2002
09:29 AM SpeedEvil: rue_mohr: Well.
09:29 AM SpeedEvil: rue_mohr: There is always the low-rent option available now.
09:30 AM SpeedEvil: chip-LIDAR with a leetle lens and servo or spinning mirror
09:45 AM edmoore: oh well, 3 years it is then
10:07 AM armyofevilrobots: Make sure to put a really sturdy bumper on it. Hate to smash it’s brains out on the first fall.
10:25 AM armyofevilrobots: (speaking from experience on a similar project :( )
10:27 AM edmoore: armyofevilrobots: at me?
10:27 AM armyofevilrobots: No, at branjb^
01:00 PM mrdata_ is now known as mrdata
01:07 PM evilroot: rue_bed, naw NC
01:07 PM evilroot: US
07:48 PM rue_shop3: Tom_itx, does your program work out speed/feed rates?
07:49 PM rue_shop3: armyofevilrobots, does yours?
07:49 PM armyofevilrobots: Program?
07:49 PM rue_shop3: I have a 1/8" bit, 6040 aluminum, and up to 23000 rpm
07:50 PM armyofevilrobots: Oh. Hmmm. Flutes?
07:50 PM rue_shop3: ah, 2
07:50 PM rue_shop3: I was just dialing down the speed, I had been at 8k, it looks like it might be ok with downwards of 3k
07:50 PM rue_shop3: chatters a lot at 8k
07:51 PM rue_shop3: not that nice metal-being-shaved-away sound
07:52 PM armyofevilrobots: So… 10ipm and 10kRPM?
07:53 PM rue_shop3: uh
07:53 PM armyofevilrobots: Hold on, I think I messed something up.
07:54 PM rue_shop3: 254mm/min sounds kinda high
07:54 PM rue_shop3: I can only go up to about 90?
07:54 PM armyofevilrobots: Really? This isn’t on the sherline then?
07:54 PM rue_shop3: 90 or 60
07:54 PM rue_shop3: my new mill
07:55 PM rue_shop3: the sherline jobs pretty good under grbl tho
07:55 PM rue_shop3: jogs
07:55 PM armyofevilrobots: You don’t wanna under-speed because it’ll gum up the bit.
07:55 PM rue_shop3: crisco? :)
07:55 PM armyofevilrobots: But if you’re getting chatter, then maybe it’s a rigidity issue? Is anything getting loose?
07:56 PM rue_shop3: gave it a strangle and shake test, seems pretty good
07:56 PM rue_shop3: maybe I need spiral paths :)
07:56 PM armyofevilrobots: Alright. Well, maybe the lower RPM is a a good plan then.
07:56 PM rue_shop3: I'll sit down and play feed-rate-chicken sometime
07:57 PM rue_shop3: see who gives up first
07:57 PM armyofevilrobots: You don’t wanna heat it up, and you don’t want start rubbing, so if you only get 3.5IPM flat out, then maybe 3500RPM and REALLY SHALLOW cuts?
07:58 PM rue_shop3: cuts are...
07:58 PM rue_shop3: .4mm
08:00 PM armyofevilrobots: That’s shallow all right.
08:01 PM armyofevilrobots: but maybe experiemnts are in order...
08:02 PM rue_shop3: but its telling you almost 1k/ipm eh?
08:03 PM armyofevilrobots: That was a combination of memory and a quick check on a calculator.
08:03 PM armyofevilrobots: BUt I would de-rate on the sherline quite severely, and wrangle the spindle speed as it was working to figure out the sweet spot.
08:03 PM armyofevilrobots: You probably have to do the same.
08:04 PM evilroot: Yay!
08:04 PM evilroot: Almost all my spare bots are sold!
08:04 PM rue_shop3: it seems that side force on the bit is the more limiting factor, and I'v not seen any calculators take that in mind
08:04 PM armyofevilrobots: All the online calculators are really based on some super-rigid cast-iron machines that are running larger tools and have spindles that won’t slow down.
08:04 PM rue_shop3: so I'v had no luck with the 1mm bits
08:04 PM evilroot: Then I can get started with more fun stuff
08:05 PM armyofevilrobots: Our old hamai machines would happily hog 1/4 inch cast iron with the TOOLHOLDER if you screwed up the tool depth.
08:05 PM armyofevilrobots: but only once.
08:05 PM rue_shop3: hehehe
08:10 PM armyofevilrobots: http://sherline.com/test-cuts/ <- maybe useful?
08:11 PM armyofevilrobots: Agh, nope, wrong machine.
08:27 PM Tom_itx: rue_shop3, yes it does feed/speed
08:28 PM Tom_itx: http://zero-divide.net/index.php?page=fswizard#
08:29 PM Tom_itx: you have to hunt a little there for it now but that's a decent one too
08:29 PM Tom_itx: or put it on your android
08:37 PM Tom_itx: 3k rpm 95mm/min? with a .0159mm/tooth chip load
08:39 PM Tom_itx: that's for mild steel though
08:42 PM armyofevilrobots: Weirdly, aluminum is more difficult than steel (IMHO), since it loads up the tool with gooey aluminum much easier.
08:42 PM armyofevilrobots: But those numbers sound reasonable for me, esp. if running a shallow cut.
08:42 PM Tom_itx: yeah the online thingy isn't being nice to me
08:43 PM Tom_itx: and i'm used to inch chiploads
08:43 PM armyofevilrobots: I don’t think they’re really that useful once you get to narrow little tools either.
08:43 PM armyofevilrobots: Or at least, their accuracy is tuned for bigger endmills.
08:43 PM Tom_itx: on his little machine i'd say .002 or .003" chipload for aluminum is reasonable
08:44 PM armyofevilrobots: Yeah. I was guesstimating .002 earlier.
08:46 PM Tom_itx: http://tom-itx.no-ip.biz:81/~webpage/cnc/pendant/milling2.jpg
08:47 PM Tom_itx: i did that ~2500-3000rpm at around 2.5 ipm
08:47 PM Tom_itx: on my sherline
08:47 PM Tom_itx: and it did good
08:47 PM Tom_itx: 2 flute carbide
08:47 PM armyofevilrobots: but it’s tricky, since he’s gonna get more deflection (a lot more) than his engagement.
08:47 PM Tom_itx: http://tom-itx.no-ip.biz:81/~webpage/cnc/pendant/pendant2.jpg
08:47 PM armyofevilrobots: Nice^
08:48 PM Tom_itx: very useful too :)
08:48 PM Tom_itx: http://tom-itx.no-ip.biz:81/~webpage/cnc/pendant/profile.jpg
08:48 PM Tom_itx: nearly done cutting there
08:49 PM armyofevilrobots: Cannot wait until I finish my current workshop upgrades so I can get a metal machine again.
08:50 PM evilroot: What kind of machine you looking at?
08:50 PM Tom_itx: wish i had time/funds to make a more rigid one
08:50 PM armyofevilrobots: I am probably going to homebuild again.
08:51 PM Tom_itx: it's a big letdown going from the big machines to my little sherline
08:51 PM evilroot: I do still have two bots left
08:51 PM evilroot: Industrial grade Cartesian goodness :-D
08:51 PM Tom_itx: rue's welded frame one should do ok i would think
08:51 PM Tom_itx: i'm running linuxcnc on my sherline
08:51 PM evilroot: I run LinuxCNC on my bots too
08:52 PM evilroot: Use them for milling aluminum
08:52 PM evilroot: Thinking of making one a giant 3D printer
08:52 PM Tom_itx: yeah i see you over there
08:52 PM rue_mohr: hmm
08:52 PM rue_mohr: 3 of us cnc eh>?
08:52 PM rue_mohr: 4, you didn't count me
08:52 PM evilroot: The two I have left are 600x400x200mm bots
08:52 PM rue_mohr: oh, sorry
08:52 PM Tom_itx: rue_mohr, did you see what s/f i used on that face for my pendant?
08:52 PM armyofevilrobots: Once this is done: https://files.armyofevilrobots.com/f/3eee90b09d/
08:53 PM evilroot: They don't make em like they used to
08:53 PM rue_mohr: yes, I prefer a wheel
08:53 PM armyofevilrobots: Upgrading to all linear rails, and there is a 15W laser for marking in there too.
08:53 PM evilroot: https://images.craigslist.org/00U0U_49lRDkBG89p_1200x900.jpg
08:53 PM rue_mohr: armyofevilrobots, did you remember a pilot laser?
08:53 PM rue_mohr: I have a small box of them
08:53 PM evilroot: https://images.craigslist.org/00K0K_hhj6sJhnL4x_1200x900.jpg
08:53 PM armyofevilrobots: rue_mohr: Yep. Got 3.
08:54 PM Tom_itx: wish i had some decent rails like that
08:54 PM evilroot: These ones use THK SR-W series
08:54 PM armyofevilrobots: evilroot: Neat stage! What’s it out of?
08:54 PM Tom_itx: you think those are rigid enough for steel?
08:54 PM evilroot: About the best you can get
08:54 PM evilroot: Tom_itx: yes
08:54 PM rue_mohr: is that a geared dc drive?
08:54 PM armyofevilrobots: Ah, NM,. I see.
08:54 PM Tom_itx: double slides on both axis?
08:54 PM evilroot: Yes
08:55 PM evilroot: One all three
08:55 PM evilroot: Plus a 360" high precision rotating toolhead mount
08:55 PM evilroot: rue_mohr: not geared. Direct drive DC servo
08:55 PM evilroot: 70V 500W on the Y
08:55 PM rue_mohr: odd, with a pitch that low
08:56 PM evilroot: 350W X
08:56 PM evilroot: They're beasts . . . 60 micron X/Y, 40 Z
08:56 PM evilroot: 1000mm/sec speed
08:56 PM rue_mohr: whats the pitch? 20mm?
08:56 PM evilroot: Something like that, not sure off the top of my head
08:57 PM evilroot: Payload cap on them is 15kg at the toolhead
08:57 PM evilroot: Fricking monsters
08:57 PM evilroot: Bought them at auction from a fab shop that was closing down . . . had to buy ALL of them though
08:57 PM evilroot: 14 total
08:58 PM Tom_itx: http://www.ebay.com/itm/US-Ship-20mm-Square-Block-Linear-guide-rail-3-Ballscrew-1605-400-700-1000-BK-BF-/142517080387?hash=item212eae1143:g:wmsAAOSwZfFZeFJ~
08:58 PM Tom_itx: those look ok or not?
08:58 PM evilroot: I'm down to just 5 now
08:58 PM rue_mohr: were they g-code?
08:58 PM evilroot: Three I use
08:58 PM rue_mohr: controllerless?
08:59 PM evilroot: I have the original controllers
08:59 PM evilroot: They use a proprietary language called DARL
08:59 PM rue_mohr: ah
08:59 PM rue_mohr: I didn't name the proprietory language I came up with for mine, shame
08:59 PM Tom_itx: good i can patent it then..
08:59 PM evilroot: I have the manuals, but personally I just used a few Geckodrive modules and a breakout for LinuxCNC
09:00 PM rue_mohr: hah
09:00 PM Tom_itx: evilroot using steppers or servos?
09:00 PM evilroot: The encoders hook right up to the modules, so easy
09:00 PM evilroot: Tom_itx: they're high precision brushed DC servos
09:00 PM rue_mohr: did they use a 8051 and some pid co-processors?
09:00 PM Tom_itx: $$$
09:00 PM evilroot: I got a good deal on them
09:01 PM evilroot: I've been selling the ones I have for $800-1200 depending on the size
09:01 PM rue_mohr: huh
09:01 PM evilroot: Sold 9 so far, down to only two I don't need
09:01 PM Tom_itx: rue_mohr, did you try that zero offset thingy?
09:01 PM Tom_itx: set zero here..
09:02 PM rue_mohr: ?
09:02 PM rue_mohr: oh no
09:02 PM rue_mohr: all the machines are playing
09:02 PM Tom_itx: G something L20
09:02 PM evilroot: The original controllers were 1991, so they use a mashup of giant H-Bridges and all manner of discreet logic
09:02 PM rue_mohr: well, hmm
09:02 PM rue_mohr: the sherline isn't , but I'm also half asleep
09:02 PM Tom_itx: so tell the other half to get busy
09:03 PM evilroot: One guy I sold one to is using the original controller and a pendant out of sheer stubborness, but it's a hobby thing to him
09:03 PM rue_mohr: trying, consuming tea
09:03 PM evilroot: One guy was using his with steel, never did catch up with him
09:03 PM rue_mohr: manual machining with it?
09:03 PM evilroot: I don't know what he's actually doing, think he just likes playing with it
09:04 PM Tom_itx: evilroot, do these look decent or not: http://www.ebay.com/itm/US-Stock-3Set-Ballscrew-1605-400-700-1000-Square-Linear-guide-rail-BKBF-Nut-CNC/112600628788?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D41375%26meid%3D873ac0c672d545a88b3f555fabd5759f%26pid%3D100011%26rk%3D2%26rkt%3D4%26sd%3D142517080387&_trksid=p2047675.c100011.m1850
09:04 PM evilroot: Of the ones I've sold two guys are doing cabinets/furniture
09:04 PM rue_mohr: oh I have to email the meuseum and tell them they have to get their stuff
09:04 PM rue_mohr: I got two relay racks that I want to load up with 3d printers
09:04 PM evilroot: One aluminum, one art, one kayaks
09:04 PM evilroot: And one PCB milling and pick and place
09:05 PM rue_mohr: neat
09:05 PM evilroot: Tom_itx: hard to say
09:05 PM evilroot: All off-brand Chinese stuff
09:05 PM rue_mohr: the sweet stuff that comes up as the countrys manufacturing slowly dies
09:06 PM evilroot: But good feedback
09:06 PM evilroot: I'd say a decent bet
09:06 PM evilroot: rue_mohr: yeah
09:06 PM evilroot: I've been shopping surplus auctions for decades
09:07 PM evilroot: Just sold two bot last week, they shipped out today. Gotta love how cheap LTL freight is now
09:07 PM evilroot: $230 to ship one of those suckers strapped to a pallet from coast to coast
09:09 PM Tom_itx: a guy that builds cnc in UK uses them
09:11 PM Tom_itx: how long are the rails in the pic you posted?
09:11 PM Tom_itx: is that gonna be a wood router?
09:12 PM Tom_itx: or just using it as a workbench..
09:34 PM jason__: anyone know a reasonable assumption for the kerf of a laser cutter? cutting 5mm MDF
09:36 PM Tom_itx: someone in #linuxcnc would if anybody's awake there
09:36 PM jason__: I'll give it a shot, thanks
09:37 PM Tom_itx: http://nyclasercut.com/getting-started-laser-cutting/kerfs-and-laser-thickness%C2%AD/
09:37 PM Tom_itx: or try that
09:38 PM Tom_itx: ~.008"
09:38 PM jason__: hmm that works thanks
10:27 PM Tom_itx is now known as Tom_L
10:27 PM evilroot: o.O
10:27 PM evilroot: He's here too
10:27 PM evilroot: Oh, or was here first
10:27 PM Tom_L: was here first
10:29 PM evilroot: I told him .2mm
10:29 PM evilroot: So about the same, heh