#linuxcnc Logs
Nov 07 2019
#linuxcnc Calendar
12:13 AM CaptHindsight: samsagaz: https://imgur.com/zKNtBAg Z axis has ~1500mm travel
12:18 AM CaptHindsight: sorry 150mm
12:18 AM pink_vampire: light ON, light OFF, light ON, light OFF, light ON, light OFF, ...
12:18 AM CaptHindsight: 0.9 deg motor 2:1 pulleys to 800 steps per screw rev, 10 tpi
12:19 AM CaptHindsight: samsagaz: DLP printer
12:21 AM CaptHindsight: https://all3dp.com/2/what-is-a-dlp-3d-printer-3d-printing-simply-explained/
12:25 AM samsagaz: ah, i see :)
12:26 AM CaptHindsight: https://imgur.com/QoVC0eR
03:50 AM Deejay: hi
05:14 AM Tom_L: morning
05:34 AM jthornton: morning
05:34 AM XXCoder: heys
05:37 AM jthornton: I found out fatshark now makes fpv goggles for people that wear reading glasses
05:39 AM XXCoder: its annoying when some stuff isnt considered
05:39 AM XXCoder: like glasses and captioning
05:39 AM jthornton: yea
05:44 AM jthornton: yea it's Friday for me
05:44 AM XXCoder: huh
05:45 AM jthornton: 4 day weekend
05:47 AM XXCoder: oh same for me lol
05:48 AM XXCoder: im still on "wed" though
05:48 AM jthornton: we are going to Beaver Lake in Arkansas tomorrow for a few days of R&R
05:49 AM XXCoder: fun :)
05:53 AM jthornton: https://www.youtube.com/watch?v=zaMlLhgRggk
06:00 AM jthornton: 49°F with a high of 45°F today
06:01 AM XXCoder: hmmmm
06:01 AM XXCoder: lower high than current? ;)
06:01 AM XXCoder: 38f l;ow high 50f thurs
06:01 AM jthornton: yea cold front moving in today
06:02 AM XXCoder: 39f now
06:02 AM XXCoder: https://s3.crackedcdn.com/phpimages/photoshop/1/1/9/713119_v2.jpg lol
07:29 AM Tom_L: 32°F Lo 22
07:36 AM jthornton: damn debian logs are filling up my hard drive
07:36 AM jthornton: 5.7G yesterday 11G today
07:40 AM jthornton: maybe I need to upgrade the 164 packages lol
11:03 AM net|: https://github.com/tecan/Arduino-SOD compiles now, was thinking of making greeting cards with it.
11:03 AM net|: when it sees you smile it plays a sound
11:10 AM jymmmm: Greetings people of Earth (and other planets)
11:14 AM CaptHindsight: ZorbZak borata!
11:16 AM jymmmm: jthornton: I'm trying to replace my propane QC hose and run pipe. Can you see any reason I can't run 1/2" pipe instead of 3/4"? IT'll be feeding a 18K BTU heater and the generator (which has been running fine on a 1/4" QC hose) - this is all low pressure (after the main regulator)
11:20 AM Rab: <jthornton> https://www.youtube.com/watch?v=VmRUJk0ptN4
11:20 AM Rab: A+ tip
12:58 PM jthornton: which one is that?
01:04 PM Rab: jthornton, using a dowel to set Z-axis height.
01:10 PM JT-Shop2: ah yea cradek taught me that one
01:26 PM cradek: hi all! I've seen some steppers with built in drivers that hook right up to step/dir. anyone know a brand that works fine? size doesn't really matter, low power is good, they will be just holding a spool of wire.
01:30 PM JT-Shop2: not seen that before
01:30 PM Rab: cradek, some people seem to swear by Teknic ClearPath servos, which have an integrated controller with a step/dir interface...but I guess that's not exactly what you asked for.
01:31 PM JT-Shop2: ah yes I have seen them
01:33 PM JT-Shop2: http://www.fpeautomation.com/jvl/
01:33 PM cradek: I think seb had one with a DB9 that took power, enable, step/dir
01:34 PM JT-Shop2: JVL makes good ones
01:36 PM Rab: Looks like there are also aftermarket driver backpacks you can add to standard NEMA motors, e.g.: https://www.omc-stepperonline.com/integrated-stepper-motor/integrated-stepper-motor-driver-0-2a-10-28vdc-for-nema-8111417-stepper-motor
01:36 PM Rab: (Can't vouch for company or brand)
01:39 PM JT-Shop2: I've used the JVL in the past, just forgot about them
01:43 PM cradek: Rab: ha I was just looking at exactly those on ebay
01:44 PM cradek: adjustable current, adjustable microstep, looks pretty great
02:00 PM drdoc: cradek: stepperonline has a webstore that's often cheaper than their Ebay or Amazon listings
02:01 PM drdoc: https://www.omc-stepperonline.com/
02:01 PM drdoc: I've never bought from them
02:46 PM cradek: ebay was a few dollars more, but I get good return protection (since they're very cheap imported electronics I think this is worth paying a few bucks for)
02:59 PM Rab: Hey, you GD&T experts! I am producing a drawing for a part: http://reboots.g-cipher.net/g11708.png
02:59 PM CaptHindsight: OMC is in Nanjing on the way to my old factory, never used them though
03:00 PM Rab: Note that the top and bottom bolt hole circles will not line up in any cross-sectional view. However, is there any acceptable way to represent both sets of holes in a single cross-section?
03:01 PM Rab: The view at the bottom of the pic shows both sets of holes--if the LH circle were rotated 15 degrees.
03:02 PM Rab: I would prefer not to resort to 'A' and 'B' cross sections, but maybe that's the proper thing to do.
03:02 PM CaptHindsight: I've seen drawings with less info :p
03:03 PM CaptHindsight: I'd like A and B details if i was making the parts
03:05 PM Rab: That's a reasonable answer, and I guess I better go that way.
03:05 PM CaptHindsight: http://everyspec.com/NASA/NASA-GSFC/GSFC-General/download.php?spec=GSFC_X-673-64-1F_AUG1994.024768.pdf
03:05 PM CaptHindsight: Page 43 ^^
03:06 PM CaptHindsight: Offset Sections
03:08 PM CaptHindsight: but that's just NASA, they can't even convert from Metric to imperial :)
03:08 PM Rab: Hmmm, yeah. So I guess I'd omit e.g. the top left and bottom right hole in the cross-section, with plane lines to match.
03:10 PM methods_: you can do an aligned section view
03:11 PM methods_: https://i.imgur.com/qloRc37.png
03:11 PM methods_: https://i.imgur.com/SyLXq91.png
03:12 PM Rab: Yeah, I think that's what the NASA manual describes.
03:12 PM CaptHindsight: methods_: dats wut I just showdem
03:12 PM methods_: ahhh gotcha sorry didn't go to linkie
03:13 PM CaptHindsight: fabtech next week
03:13 PM methods_: yeah i'm not going this year
03:13 PM methods_: i'll go next year
03:13 PM CaptHindsight: Hazzy had some pics of the giant metal bending machine he's setting up there
03:14 PM CaptHindsight: for sheet
03:14 PM methods_: oh nice
03:15 PM CaptHindsight: too cold this year
03:16 PM CaptHindsight: Monday will be high of 21F
03:16 PM CaptHindsight: it's usually ~50F
03:16 PM methods_: yeah it's supposed to be 36f here saturday
03:16 PM methods_: i'm probably going to die or something
03:18 PM CaptHindsight: https://matrix.org/_matrix/media/r0/download/matrix.org/ThoTNyGfdEQcQNxDBCVvRoOB
03:18 PM CaptHindsight: big box
03:18 PM Rab: Riding low.
03:19 PM Rab: Maybe the suspension is pressured down.
03:19 PM CaptHindsight: 30F here now :(
03:20 PM CaptHindsight: hazzy-m: what was the clearance under that trailer?
03:20 PM CaptHindsight: looks like 6"
03:20 PM XXCoder: recent oct was warmest oct ever. quite funny that usa had one of colder octs due to votex
03:21 PM CaptHindsight: XXCoder: yeah it flipped us around, was just warm and the AC was on a few weeks ago
03:21 PM CaptHindsight: so no fall this year
03:21 PM CaptHindsight: will likely balance out ijn jan and be in the 30's vs 20's
03:21 PM XXCoder: it was fast yeah. here its at standard "late fall" weather
03:22 PM XXCoder: never had "early" and "mid-fall" weather here which is lots lots rain
03:22 PM EvilDMP: Hello, I use the cheapest SG90 (analog) servos very successfully in my plotter project, https://www.brachiograph.art - I'd like to try some digital servos, can you recommend something for a next experiment?
03:23 PM EvilDMP: I used some digital SG90 equivalents, but they are much too twitchy in this application.
03:24 PM CaptHindsight: hobby servos?
03:24 PM Deejay: gn8
03:24 PM EvilDMP: The dead band of analog servos helps prevent twitching, I am wondering if more powerful digital motors would avoid this behaviour.
03:25 PM CaptHindsight: aka RC servo
03:25 PM EvilDMP: CaptHindsight: yes, the cheapest of hobby servos.
03:27 PM XXCoder: lol this is evil https://i.imgur.com/J3KVqAI.jpg
03:27 PM XXCoder: not real one
03:28 PM CaptHindsight: EvilDMP: can you set up a digital equivalent of the analog dead band on your controller?
03:28 PM CaptHindsight: EvilDMP: are you sending twitches? it's PWM to the servos
03:29 PM EvilDMP: CaptHindsight: even if the servos are completely still, all I need to do is give one of the arms a gentle flick and it will start oscillating.
03:29 PM EvilDMP: So the slightest provocation causes it.
03:30 PM EvilDMP: The mechanical arrangement is not really what the servos are meant to be able to handle, even if the mechanism is extremely light.
03:30 PM CaptHindsight: too much load on them
03:32 PM XXCoder: EvilDMP: adjust your PID
03:32 PM XXCoder: or add it if it dont have
03:32 PM EvilDMP: XXCoder: what is a PID?
03:32 PM XXCoder: a second
03:33 PM XXCoder: https://www.youtube.com/watch?v=0vqWyramGy8
03:33 PM CaptHindsight: https://www.youtube.com/watch?v=MxJAPHxKgUg
03:33 PM CaptHindsight: XXCoder: he's using hobby servos without any position feedback
03:34 PM CaptHindsight: PWM version of Step and Dir
03:34 PM CaptHindsight: open loop
03:34 PM XXCoder: ah I guess cant use pid in this case
03:35 PM EvilDMP: oh, but I am not using any feedback...
03:35 PM EvilDMP: I am just driving the servos directly from the Raspberry Pi
03:35 PM CaptHindsight: http://www.robotplatform.com/knowledge/servo/servo_control_tutorial.html
03:35 PM XXCoder: that video is best for learning how pid work so recommanded watch anyway :)
03:36 PM CaptHindsight: my video is of a cheap robot arm
03:37 PM CaptHindsight: EvilDMP: your setup is like a SCARA
03:37 PM CaptHindsight: https://en.wikipedia.org/wiki/SCARA
03:37 PM EvilDMP: For this project, adding any cost or complexity to the basic design is not possible, because the key point of the design is to make both of those as low as possible
03:38 PM CaptHindsight: you're going to have to find the lowest cost Chinese servo that handles your loads
03:38 PM EvilDMP: Yes, SCARA does seem to have some in common.
03:38 PM CaptHindsight: https://www.alibaba.com/showroom/rc-servo.html
03:39 PM EvilDMP: CaptHindsight: I have already found the lowest cost motors - Tower Pro SG90s are pretty much that - and they work reall well
03:39 PM CaptHindsight: https://hobbyking.com/en_us/radio-servos/servos.html
03:39 PM EvilDMP: really
03:40 PM EvilDMP: I can build the entire plotter for €14 including the Raspberry Pi.
03:40 PM CaptHindsight: BUT is almost works
03:40 PM CaptHindsight: is / it
03:40 PM EvilDMP: It absolutely works, no almost about it.
03:41 PM EvilDMP: It works beautifully as you can see from the pictures.
03:41 PM EvilDMP: But, I'd also like to experiment with more expensive digital motors.
03:41 PM CaptHindsight: I thought you said that it twitches
03:41 PM EvilDMP: Only with digital motors.
03:41 PM CaptHindsight: could be noise
03:42 PM CaptHindsight: servo gets wrong data, moves unexpectedly
03:42 PM EvilDMP: Look at the examples on the page https://www.brachiograph.art
03:43 PM CaptHindsight: https://i.imgur.com/EAF5oPj.jpg working on something similar with a digital airbrush and 5 axis
03:44 PM EvilDMP: Noise could start an undesired movement, but I am pretty sure that what causes the oscillation is the digital motor trying to correct, overshooting, trying to correct, etc, because it is not powerful enough to control better.
03:45 PM EvilDMP: That is certainly a few steps in sophistication above mine...
03:45 PM CaptHindsight: so you are on the right track
03:46 PM CaptHindsight: off to the post office for me!
03:46 PM Rab: EvilDMP, are you seeing twitching in all joints, or just the middle one?
03:46 PM EvilDMP: someone built my design and posted a video https://twitter.com/BrachioGraph/status/1192491305210916868
03:46 PM Rab: Lemme rephrase...does one joint twitch more than the others?
03:46 PM EvilDMP: Rab: on the two am joints, and the shoulder joint is worst (as it has the mass of both arms and two motors)
03:47 PM EvilDMP: I mean, it "has to move the mass..."
03:48 PM Rab: Have you experimented with ways to reduce friction against the paper?
03:49 PM EvilDMP: Rab: no, but I have tried to *increase* it on the motor to damp the unwanted movement. There is almost no friction with the paper in practice, especially with a rollerball pen or a pencil.
03:50 PM XXCoder: I didnt expect it to be drawing turtle in real world ;)
03:51 PM EvilDMP: I will probably buy a couple of https://thepihut.com/collections/adafruit-robotics-cnc/products/towerpro-servo-motor-mg946r-metal-gear, but it will be a bit annoying if they turn out to suffer from the same oscillation as the cheaper digital motors.
03:52 PM CaptHindsight: the price of research and product development
03:52 PM EvilDMP: They have more torque, but they also weigh more... that could cancel out the advantage
03:52 PM CaptHindsight: run the numbers
03:52 PM EvilDMP: CaptHindsight: you'd be shocked how many motors I have destroyed in this project
03:53 PM CaptHindsight: how much time did you spend writing the software?
03:55 PM EvilDMP: CaptHindsight: most of this year.
03:55 PM EvilDMP: (not full time, I hasten to add)
03:56 PM EvilDMP: The first version was a pantograph, https://www.brachiograph.art/how-to/pantograph.html, which has some advantages, but is more complex.
03:58 PM Rab: Typo on that page, "BrachipGraph"
03:59 PM EvilDMP: SG92R: 9g, torque 2.5kg/cm. MG946R: 55g, torque 10.5kg.cm. Maybe the gain in torque will not make up for the weight.
04:00 PM EvilDMP: fixed, thanks.
04:03 PM Rab: Yeah, torque to weight ratio is worse for the bigger motor.
04:06 PM EvilDMP: Rab: on the other hand, it may have less sloppy gearing and overall tighter tolerances, that also helps control unwanted movement
04:07 PM Rab: EvilDMP, does performance improve if the arms are shorter?
04:08 PM EvilDMP: Rab: definitely.
04:10 PM SpeedEvil: I have not properly read up.
04:10 PM SpeedEvil: However, in principle adding preload - radial spring - could remove some of the slop.
04:12 PM EvilDMP: SpeedEvil: it definitely would, and I can prevent the oscillation just by gently putting a finger against the arm - but it would go against the cheap and simple principle.
04:12 PM SpeedEvil: Elastic bands are springs too
04:13 PM EvilDMP: I did try once, with elastic bands wrapped around the motor axis in fact.
04:13 PM gregcnc: RC servo vary wildly in quality
04:27 PM EvilDMP: Anyway, thanks everyone for the feedback and suggestions, it has been a much nicer experience than trying to ask the same questions on StackExchange and being told that I am stupid.
04:42 PM SpeedEvil: EvilDMP: https://spritesmods.com/?art=jello3dprinter
04:43 PM EvilDMP: Ingenious!
05:25 PM JT-Shop2: cutting a 3/23" deep 1 3/4" wide rabbet on a 10' pressure treated 2x4 was not as bad as I thought it might be
05:27 PM SpeedEvil: 3/23" ?
05:27 PM JT-Shop2: typo
05:27 PM JT-Shop2: actually I reverse numbers from time to time
05:31 PM Tom_L: what you makin?
05:32 PM SpeedEvil: Oh - you actually meant 3/32. I thought about that, and dismissed it as it was too silly.
05:38 PM jthornton: fitting the boards on the trailer
05:38 PM jthornton: each side board has to have a rabbet the width and depth of the angle on top of the cross angles
05:40 PM jthornton: I guess I need to make a plasma workbench for freecad lol
05:40 PM Tom_L: heh
05:41 PM Tom_L: if you can get the source install working, you could make a custom post for it
05:42 PM _unreal_: hello
05:42 PM _unreal_: There are finally getting stuff done
05:42 PM _unreal_: with my cnc build
05:46 PM jthornton: you can't add a custom post without building it?
05:47 PM Tom_L: you're running from an executable
05:47 PM Tom_L: i don't think you can add a .py file to it
05:48 PM Tom_L: appimage
05:49 PM jthornton: System post processors are in <freecadDirectory>/Mod/Path/PathScripts/post. If you write your own, you put it in your macro directory and name it <something>_post.py.
05:50 PM Tom_L: huh
05:50 PM jthornton: so yea the appimage still might work but where is my macro directory
05:50 PM Tom_L: https://discourse.appimage.org/t/adding-static-data-files-to-an-appimage/328
05:51 PM Tom_L: you would still need to be able to select it as your output post
05:51 PM Tom_L: i dunno how that would work
06:02 PM _unreal_: fdsasdf3245asdfasdfsadasdfsdf36
06:02 PM jthornton: exactly what I was thinking
06:02 PM _unreal_: wrong keyboard
06:02 PM jthornton: yea it's Friday!
06:03 PM Tom_L: heh
06:03 PM Tom_L: have fun
06:03 PM jthornton: I will try
06:03 PM Tom_L: where you off to this time?
06:04 PM jthornton: Beaver Lake Arkansas
06:04 PM Tom_L: gettin a bit chilly to hang out at the lake ehh?
06:05 PM jthornton: ah we just go for the view and to relax
06:06 PM jthornton: they have a big cat place, I think it's the larges bit cat rescue place in the US
06:06 PM jthornton: and Eureka Springs is only a few miles away
06:06 PM Tom_L: been there
06:06 PM Tom_L: been a while though
06:07 PM jthornton: did you eat at the old hotel?
06:08 PM Tom_L: no
06:08 PM Tom_L: we didn't get to stay that long
06:08 PM jthornton: best pizza I've had
06:08 PM jthornton: kinda hard to find the place
06:08 PM Tom_L: when the kids were young, we had someone watching them
06:08 PM Tom_L: so we went and just got settled in and got a call that one went to the hospital and had stitches
06:09 PM Tom_L: that was the end of the trip :)
06:09 PM Tom_L: drove back home thru the night
06:09 PM jthornton: crap
06:09 PM jthornton: 6-8h back?
06:09 PM Tom_L: we did have time to look around some and take a carriage ride etc
06:09 PM Tom_L: i don't remember now
06:10 PM Tom_L: that was ages ago
06:10 PM Tom_L: sounds about right
06:10 PM jthornton: yea we need to do the carriage ride when it's not so cold
06:11 PM Tom_L: went thru the hotel i think it is... the one that's supposed to be haunted
06:12 PM jthornton: Crescent Hotel
06:12 PM Tom_L: yeah that sounds right
06:12 PM Tom_L: went down in one of the caves
06:13 PM Tom_L: forget which one
06:13 PM jthornton: pizza restaurant is on the top floor so if the weather is ok you can sit outside
06:13 PM Tom_L: cool
06:13 PM jthornton: yea pretty good view of the area
06:14 PM jthornton: I should bring my phantom and take some aerial videos
06:22 PM Tom_L: gonna try to compile this on stretch
06:22 PM Tom_L: freecad..
06:24 PM jthornton: ok
06:33 PM jthornton: chili con carne time
06:37 PM Tom_L: well... i'm not going down dependency road tonight.
07:37 PM CaptHindsight: https://spritesmods.com/?art=jello3dprinter&page=1
07:37 PM CaptHindsight: Jello 3d printer, I didn't know I needed this
07:38 PM CaptHindsight: https://www.youtube.com/watch?time_continue=3&v=VluX6g63dqk
08:17 PM hazzy-m: CaptHindsight: not enough clearance under that trailer. He scrapped quite a bit leaving our parking lot, which is pretty much dead flat. I'd say he had 5" of clearance. Don't see how he does get stuck all the time
08:17 PM _unreal_: CaptHindsight, https://web.archive.org/web/20140824231131/https://spritesmods.com/?art=jello3dprinter&page=2
08:19 PM hazzy-m: He was oversize and overweight as well, bit he made it here to Chicago!
08:20 PM * hazzy-m uploaded an image: ima_12417d6.jpeg (179KB) < https://matrix.org/_matrix/media/r0/download/matrix.org/DfYoVpYXUnwrDpHyIvWFWSlj >
08:21 PM * hazzy-m uploaded an image: ima_20ac3e0.jpeg (194KB) < https://matrix.org/_matrix/media/r0/download/matrix.org/xoYhnUIdgWDBPUelSzSNxpjk >
08:21 PM * hazzy-m uploaded an image: ima_227ad53.jpeg (186KB) < https://matrix.org/_matrix/media/r0/download/matrix.org/rnKvFstWxFfSmvKRMNvNyMzg >
08:23 PM hazzy-m: It was a royal pain puting the crate back together... After the show we have to take it apart again to put the machine in for it's trip to it's final destination in Montreal
08:24 PM * hazzy-m uploaded an image: ima_020ab1d.jpeg (170KB) < https://matrix.org/_matrix/media/r0/download/matrix.org/CIXKwkTVyklfqkyagFxcAYBL >
08:25 PM hazzy-m: Tormachs booth, took some sneak peaks in the crates :)
08:25 PM * hazzy-m uploaded an image: ima_5ad6be0.jpeg (147KB) < https://matrix.org/_matrix/media/r0/download/matrix.org/rhvYDDNjuykBjhgNJYbIqrpx >
08:26 PM hazzy-m: Sorry for the spam lol
08:32 PM hazzy-m: If any of you all are going to FABTECH be sure to stop by the MetalForming booth (A2162) for a chat and demo!
08:34 PM hazzy-m: I brought plenty of demo parts, including various NEMA and machine tool control enclosures. I'll be folding up doors and wireing backplanes for them as well, if anyone is interested in free enclosures
08:36 PM hazzy-m: Also I can give you a registration token so you can get in for free
08:49 PM CaptHindsight: hazzy-m: can I bring my own materials to be folded? :)
08:52 PM CaptHindsight: _unreal_: mine will have all linear servos :)
09:02 PM _unreal_: hum
09:02 PM _unreal_: just finished din din, yuka in curry with pepper and garlic, with pork steaks
09:13 PM _unreal_: ! OMG rob shnieder is almost 60?? wtf
10:17 PM skunkworks: Kids I went to school with are dying... I swear I am not 'that' old.
10:19 PM Tom_L: i bet you're just a pup
10:29 PM skunkworks: 46ish
10:50 PM CaptHindsight: _unreal_: but his wife is only 31 https://www.imdb.com/name/nm2317437/
10:51 PM CaptHindsight: skunkworks: yeah, spooky at first, but it tends to be those that had a pretty hard life that go first