#linuxcnc Logs

Jun 23 2018

#linuxcnc Calendar

01:54 AM IchGucksLive: hi all from a nice sunrise in Germany
01:58 AM IchGucksLive: Lcvette_1, you need a bigger mashine
01:58 AM IchGucksLive: on that toolsetup
01:58 AM IchGucksLive: the toolstorige is larger then the intirer mill
01:58 AM IchGucksLive: im off 2 Garden Bye
01:58 AM Lcvette_1: That's my little mill
02:02 AM XXCoder: ich always say that
02:03 AM Lcvette_1: Lol
02:27 AM Deejay: moin
02:37 AM gloops: howdy
03:24 AM gloops: hmm, getting to the point where im thinking of making a bandsaw for slicing logs
03:25 AM XXCoder: woodgear one?
03:25 AM gloops: my old router skate bearings can be adapted for the moving rails, in fact its basically a gantry
03:25 AM gloops: similar idea
03:26 AM gloops: ive got two old fashioned car jacks with travel of about 13 inches to raise the blade up and down lol
03:27 AM gloops: just have to put ruler/line markings on either side and rely on those for setting
03:30 AM gloops: got a scrap 8 inch bandsaw - all the adjustable wheels etc ready to go
03:30 AM XXCoder: not bad, could do it yeah
03:31 AM gloops: might be a bit of a dream but theres a lot of logs laid around that could be turned into good sign boards
03:31 AM gloops: the machine is easy to make though
03:32 AM gloops: hardwood is staggeringly expensive here, oak boards of any width are like £30 a foot
03:33 AM XXCoder: ow
03:35 AM RyanS: I think it's pretty expensive here too, we get Tasmanian oak
03:36 AM Deejay: hr, its oak :D its always expensive
03:38 AM RyanS: recycled timber costs heaps, definitely not as cheap as youd think, I guess anything used in trendy shop fitting commands a high price
03:39 AM gloops: well, an old oak railway sleeper is £15 - 12x8 inch 10 foot long
03:40 AM gloops: the outside is hammered in creosote and tar oil, but if you slice that off theres a pretty valuable beam inside
03:40 AM gloops: nobody has the saw to cut them up though, not diyers
03:41 AM RyanS: could make a chainsaw jig
03:41 AM Wolf__: probably eat blades cutting that coating
03:41 AM gloops: could do, chainsaws are noisy and dangerous though, not much of an option for UK back yard operations
03:42 AM gloops: bandsaw is very little resistance and quiet
03:42 AM gloops: Wolf blades might get tarred up yes
03:42 AM RyanS: yeah maybe a portable bandsaw
03:43 AM XXCoder: oak isnt that bad here, I guess easier to get
03:43 AM XXCoder: still quite a bump in price
03:44 AM Wolf__: usa has a bit more land mass for lumber
03:45 AM gloops: used to be a rule here that every field had to have an oak tree planted at a set distance - was for the old wood naval ships
03:45 AM gloops: theyve mostly gone now
03:46 AM RyanS: hmm, I wonder if my 3d printer dislikes this 5 meter USB extension lead..
06:33 AM jthornton: 6 pound field cannon parts had to be made from white oak, I have a copy of the plans
06:39 AM miss0r: why? :D
06:40 AM XXCoder: because.
06:41 AM unterhausen: white oak is strong, rot resistant
06:42 AM unterhausen: there was a pallet manufacturer near here that always had huge piles of white oak sitting outside
06:43 AM unterhausen: white oak has closed pores, most oaks are open pore
06:43 AM XXCoder: nice
06:43 AM XXCoder: price compare with say regular oak?
06:43 AM jthornton: white oak is regular oak
06:44 AM XXCoder: sorry I meant compared with others
06:44 AM jthornton: dang a cold front i moving through
06:44 AM jthornton: white oak is the only one you see for sale
06:44 AM jthornton: oh no you can get red oak too
06:45 AM XXCoder: yeah thats what I was thinking about lol
06:45 AM XXCoder: I was wondering if I misremembered lol
06:45 AM jthornton: I forgot when I was building the cannons I got some red oak then read the plans again lol
06:50 AM Tom_itx: 60F
06:50 AM Tom_itx: nice rain cooled things off
07:14 AM Lcvette: Hot and muggy here
07:29 AM jthornton: .weather
07:29 AM theCockerel: Yahoo! Weather - Poplar Bluff, MO, US: Mostly Cloudy, 18°C (64°F), Humidity: 97%, Light air 1.8m/s (↙)
08:00 AM alex_joni: nifty ;)
08:00 AM alex_joni: .weather
08:00 AM theCockerel: I don't know where you live. Give me a location, like .weather London, or tell me where you live by saying .setlocation London, for example.
08:01 AM alex_joni: .setlocation Timisoara
08:01 AM theCockerel: alex_joni: I now have you at WOEID 881802 (Timisoara, Timis, Romania)
08:01 AM alex_joni: .weather
08:01 AM theCockerel: Yahoo! Weather - Timisoara, Timis, RO: Mostly Cloudy, 18°C (64°F), Humidity: 48%, Gentle breeze 4.9m/s (↘)
08:27 AM Lcvette: NC
08:27 AM Lcvette: Wilmington,NC
08:41 AM gloops: think ive finally settled on how im going to have my garage laid out, got all the stuff for the bench and shelves here
08:41 AM gloops: having the vision and it becoming reality are two different things though lol
08:41 AM Lcvette: pcw_mesa: new tuning advice for drive to give more headroom on gain and ff... "P101=(if no use, decrease until motor shake) P100=(increase until motor noise)" soooo... What's that sound like?
08:42 AM Lcvette: Maybe those filters?
08:50 AM Lcvette: Also I'm now curious about velocity mode, would that be smoother than position mode? Or
08:50 AM Lcvette: Gloops: lay it out in cad
09:11 AM gloops: well it isnt going to be anything precise and only a small space really Lcvette, ive just worked it out by looking round and saying 'if that was here and this was there' etc
09:16 AM Lcvette_1: Small spaces can be maximized sometimes with careful planning
11:22 AM Lcvette_1: pcw_mesa: i read through the drive manual looking for how it could be used in velocity mode without the ability to accept an analog reference and was unable to find what you were seeing. The only input type this model drive accepts is a pulse, so I'm assuming you saw that it could convert a pulsetrain to a voltage signal? Or was i misinterpreting?
11:49 AM Lcvette: pcw_mesa: http://imgur.com/gallery/nHde2QS
11:49 AM Lcvette: Everything seems to want it to switch to analog for velocity mode
12:48 PM pcw_home: Its just tuning, you can do velocity mode with step/dir
12:51 PM pcw_home: you just take the position feedback out of the loop (by setting the drives position feedback gain to 0)
12:58 PM IchGucksLive: hi all
12:58 PM IchGucksLive: pcw_home, do you know if the china Hss86 suports this mode
12:59 PM IchGucksLive: .weather Zweibrücken
12:59 PM theCockerel: Yahoo! Weather - Zweibrucken, RP, DE: Cloudy, 18°C (64°F), Humidity: 48%, Moderate breeze 6.3m/s (↓)
01:02 PM IchGucksLive: jthornton, got the same weather here
01:02 PM IchGucksLive: but it will head up from tomorrow
01:06 PM pcw_home: There is _NO_ connection between velocity mode and analog
01:07 PM pcw_home: it all in how the control loop runs in the drive
01:08 PM pcw_home: if you set velocity feed forward to 100% and position mode feedback to 0 you have a velocity mode drive even if it gets velocity commands via carrier pigeon
01:11 PM MrHindsight: CP-PID as we used to call it
01:11 PM IchGucksLive: thanks i need to get my brain behind this pid systems
01:12 PM Lcvette: Ah i see
01:13 PM IchGucksLive: i try to stay till real pention on stepeprs conventional as we got so many peple upset by updating there configs and then nothing goes forward as the ini changed dramaticly
01:14 PM IchGucksLive: i personly feel that in the new education year i might loose 400+ mashines i build on linucnc to arduino
01:15 PM Lcvette: I guess that would make sense if the fact that changing the speed loop gain and speed loop integral time constant has a direct effect on the position gain range and position FF
01:15 PM IchGucksLive: and if we are only 2 handfull of active we will get lost in space
01:16 PM IchGucksLive: Lcvette, you are the man in frontline to test this out male a video and write a advice
01:17 PM MrHindsight: IchGucksLive: sounds like the dumbing down of educational systems has reached your department
01:17 PM IchGucksLive: im off 2 beergarden to watch a soccer game kicking germans worldchampion of the championchip ;-)
01:18 PM IchGucksLive: MrHindsight, im the only one that takes action on cnc
01:18 PM IchGucksLive: MrHindsight, in 200miles range i think
01:18 PM IchGucksLive: bye
01:21 PM roycroft: i found an a3 autocad template that does the scaling properly
01:21 PM roycroft: interestingly, it does the metric-inches conversion in the plotter manager
01:21 PM MrHindsight: they could save even more money by just offering virtual CNC machines to students
01:21 PM roycroft: so i am making progress
01:22 PM Lcvette: Yeah i will certainly be making some video of all of this
01:23 PM Lcvette: I think it would be helpful for those like me who learn easier with some visual representation
01:23 PM Lcvette: Popup books and the like
01:25 PM Roguish: roycroft: hey, i'ld like to see how that's done.
01:29 PM Gerhard is now known as Guest89134
01:29 PM Guest89134: hallo !
01:32 PM Guest16235: Hi, anybody knows where i can find a small simple python script for linuxcnc which can just do some simple movement of X, Y and Z axis?
01:33 PM cpresser: Guest16235: http://linuxcnc.org/docs/2.6/html/common/python-interface.html#_sending_commands_through_tt_linuxcnc_command_tt
01:34 PM Guest16235: cpresser: yeah i actually tried running that script, but its broken
01:34 PM cpresser: there is the .mdi and the .jog function
01:34 PM cpresser: what is broken?
01:34 PM Guest16235: that script
01:35 PM cpresser: details plz
01:35 PM Guest16235: its using an undefined variable: program_start_line
01:35 PM cpresser: obviously, because its undefined. delete all those commands that make no sense.
01:35 PM cpresser: keep the .mid function call
01:36 PM Guest16235: hmm ok...but its difficult to know which lines makes no sense for a beginner...essentially its all of them in the beginning :)
01:36 PM Guest89134: vielleicht liest trotz fussball ein deutscher mit. ich habe ein problem mit timingeinstellungen bei verwendung von unterschiedlichen controllern. dcs810 für x und y und tb6600 für z separat laufen beide sorten gut, die dcs mit 50ns und die tb mit5500. die tb benötigt eine größere signaldauer und die legt meine servos quasi lahm wenn ich für die schrittmotorenkarte einstelle.
01:37 PM Guest16235: Guest89134: axis is also undefined
01:37 PM cpresser: Guest16235: i could answer in german, its my native language. _but_ i think you need to learn to read that code. and its in english
01:37 PM cpresser: try to help yourself. it takes some time
01:37 PM cpresser: but its worth the effort :)
01:37 PM Guest16235: cpresser: ich sprecht deutch
01:38 PM Tom_itx: Lcvette, video hell... you should write a book by now :)
01:38 PM cpresser: ich auch, aber ich mache dir vermutlich keinen gefallen wenn ich dir das auf deutsch erkläre und das problem löse. ich helfe lieber menschen zu lernen wie sie selbst probleme lösen können.
01:40 PM cpresser: Guest16235: where are you located in germany? go visit a hacker/makerspace. they like cnc-machines, and can help you lern/understand python
01:40 PM Guest16235: cpresser: no, i am in denmark so i am not native in german but i understand quite a lot
01:41 PM cpresser: Guest16235: ah sorry. anyway, see if there is a hackerspace close to you.
01:41 PM Guest16235: hmmm
01:41 PM Guest16235: i dont think there is
01:42 PM Guest16235: ok,...guess im on my own then
01:42 PM Guest16235: thanx
01:43 PM cpresser: https://www.python.org/about/gettingstarted/
01:46 PM cpresser: https://wiki.hackerspaces.org/denmark
01:51 PM Guest16235: it sounds like a coffee shop :)
01:54 PM Guest16235: Ok...i have done my stepconf wizard and my axes are moving when i am testing them in stepconf wizard. I save my config file....then i open linuxcnc and choose my config file, which then opens the program Axis. In axis I try pressing "Toggle Emergency Stop" - but it has no effect. What am I missing?
01:58 PM Guest89134: 16235 did you do homing ?
01:58 PM cpresser: did you configure the e-stop?
01:58 PM cpresser: there is also a machine on-off button in axis
01:58 PM Guest16235: cpresser: in stepconf wizard?
01:58 PM cpresser: in axis
01:58 PM Guest16235: cpresser: ah hmm no i did not. Where is that done?
01:58 PM cpresser: on-off is next of the estop button in axis
01:59 PM Guest16235: cpresser: yes but this button is greyed out so i cannot click it
01:59 PM cpresser: but you need to configure the on/off and e-stop in stepconf to work properly. usually on/off is tied to the enable pins of the drivers
01:59 PM Guest16235: aha ok
02:00 PM cpresser: perhaps your drives have an enable pin
02:00 PM cpresser: anyway, you should try to setup estop-in and estop-out in stepconf
02:00 PM Guest16235: cpresser: yes pin1 is ESTOP out and pin 10 is ESTOP in
02:01 PM cpresser: then the next step is checking their function with a multimeter
02:01 PM Guest16235: i dont have a multimeter
02:01 PM cpresser: any other device to measure voltage?
02:01 PM Guest16235: no
02:03 PM cpresser: shit. that would be the natural next step for debugging
02:03 PM Guest16235: cpresser: i actually have both my pin1 and pin14 set to ESTOP Out (pin1 is inverted and pin 14 is not). Is that a problem?
02:04 PM cpresser: that might be an issue.
02:05 PM fragalot: Hi
02:05 PM Guest16235: cpresser: hmm but how do people set up these CNC machines so they actually work....it seems like really impossible.....it was only by pure luck that i actually made the axis move around in stepconf wizard
02:06 PM cpresser: to be honest, i cant answer that. i already know how to do it. so i can't really imagine not knowing how to do it
02:06 PM cpresser: i am biased to 'its easy to do'.
02:06 PM fragalot: I can - it's either luck or perseverance
02:07 PM Guest16235: cpresser: :( I wish i had your knowledge on these machines
02:07 PM cpresser: bu i am also an electrical engineer
02:08 PM Guest16235: i just want these axes to move so that i can begin writing software....but getting the axis to move is just not possible it seems...so many unknowns, so many errors
02:08 PM fragalot: I've never gotten the axis to actually move in stepconf
02:08 PM fragalot: i'm fairly confident there's a bug somewhere that nobody seems to fix
02:08 PM gloops: Sweden have scored ...oh Germany
02:08 PM Guest16235: fragalot: mine actually does move in stepconf heh
02:09 PM fragalot: oh :P
02:09 PM Guest16235: fragalot: but nowhere else.....thats not true...in winXP everything worked perfectly out of the box :D easy peacy
02:09 PM cpresser: stepconf also worked fine for me on my first machine.
02:09 PM fragalot: cpresser: it worked on my first machine many years ago, but my recent one using mesa cards did not
02:10 PM Guest16235: cpresser: say i actually had a multimeter (i can buy one on monday) How would that then help me?
02:11 PM cpresser: my advice is: get the schematic of your controller; learn the basics required to read it. redo stepconf with that knowledge. get a multimeter to debug it
02:11 PM Guest16235: cpresser: its a chinese mill (3040)...i dont think there are any schematics
02:11 PM cpresser: multimeter should be used to measure the voltage on estop-out. it should change when estop-in is toggled
02:12 PM cpresser: if there is no schematic, reverse-engineer it using eyes, pen&paper and a multimeter
02:12 PM Guest16235: heh
02:12 PM Guest16235: can i hire you to do it :D
02:13 PM cpresser: i can do it for free; just come to the aachen hackerspace :)
02:13 PM Guest16235: i might just do that
02:13 PM Guest16235: actually
02:13 PM Guest16235: haha
02:14 PM Guest16235: its just a 9 hour drive
02:14 PM gloops: sling the random BOB out and get the standard mach3 BOB, everyone is familiar that
02:15 PM Guest16235: When do you guys meet up next time in Aachen Hackerspace
02:15 PM gloops: decent match on for anyone who likes football - sweden v germany
02:21 PM cpresser: Guest16235: every wednesday and friday
02:22 PM cpresser: but seriosly, that seems stupid, 9h drive.
02:26 PM gloops: the only time id consider a 9 hour drive to help someone out would be if Gill Ellis Young was having trouble with a faulty bikini
02:27 PM hazzy-dev: lol gloops
02:50 PM ziper: who the heck
02:51 PM hazzy-dev: Ok, OT question: I am working on an "adjustable depth" pool. It is a rather large 10ft deep pool with a slatted platform in it that can be raised up and down by hydraulic powered winches at each corner to adjust the depth. It can go all way up to flush with the surrounding deck so you don't have that big hole in your yard when it's not swimming season. Also good to make a wading pool for the smaller kids ..
02:52 PM hazzy-dev: Problem is, for some reason the hydraulic power unit is not building pressure any more, or the motors have worn so they are leaky, anyway, the result it that the deck no longer can be raised up
02:52 PM hazzy-dev: The hoses are also shot, and they'd have to break up the pool deck to replace them ..
02:53 PM hazzy-dev: So I am thinking about replacing the hydraulic motors with electric ones to simplify the system
02:54 PM hazzy-dev: it only takes about 150in-lbs to turn the input shaft on the gear box, so I am thinking a gear motor should be able to do that
02:56 PM hazzy-dev: I am having trouble finding motors that can supply that torque though, most are puny little things, or much bigger than needed. Any ideas for motors that would be a near drop in replacement for hydraulic motors?
02:56 PM hazzy-dev: https://i.imgur.com/pVP6v2M.jpg
02:57 PM hazzy-dev: 12 N-m steppers with a little timing belt reduction would work, but thats overkill ..
03:00 PM XXCoder: dang the rust
03:06 PM hazzy-dev: XXCoder: Yeah, it's a salt water pool .. I'm going to redo all those parts
03:06 PM XXCoder: wonder if you could set it to be protected more
03:06 PM XXCoder: like say powder coat or something
03:08 PM hazzy-dev: It was powder coated, but not very well. Thinking about making it out of stainless, I could simplify it so it would not use as much material
03:08 PM XXCoder: stainless with powder coat would last long time I guess
03:09 PM gloops: no need for any control of the shaft angle though - so no need for stepper type motors
03:14 PM XXCoder: interesting. someone hacked trump hotel website
03:15 PM gloops: Germany down to 10 men!
03:15 PM hazzy-dev: gloops: That's right, but I can't find any motors that have have the needed low speed high torque and and small size
03:17 PM fragalot: hazzy-dev: I think i've got some small DC motors with a little planetary gearbox on 'm that can give out around 60Nm, at around 60rpm I think?
03:17 PM fragalot: came with a tiny encoder too :P
03:18 PM hazzy-dev: fragalot: That's exactly what I am looking for! Would it be difficult to get the name/model?
03:19 PM fragalot: let me go look if they're still marked
03:20 PM Tom_itx: i can't imagine anything lasting too long in that environment
03:20 PM fragalot: faulhaber minimotor SA, and a portescap
03:20 PM fragalot: can't read the partnumbers
03:22 PM fragalot: (and those are 2 separate motors, the portescap is a bigger one)
03:23 PM hazzy-dev: Thanks fragalot, looking
03:23 PM hazzy-dev: faulhaber has some interesting little motors
03:23 PM fragalot: yeah really high quality too
03:24 PM gloops: stairlift motor
03:24 PM fragalot: doubt those can stand any type of harshish environment, but sure those are pretty beefy too
03:25 PM Tom_itx: grain auger motor
03:27 PM gloops: http://www.dumoremotors.com/dm40-dc-magnet-motors.html
03:27 PM hazzy-dev: Humm, and grain auger would be perty weather proof too ...
03:27 PM gloops: good for pumps
03:28 PM Tom_itx: or something designed for marine use
03:30 PM enleth: damn it, why didn't the soviet block make any small benchtop surface grinders?
03:31 PM enleth: there's loads of tiny cute surface grinders in the US, absolutely none here
03:31 PM hazzy-dev: I wonder is a HD windshield wiper motor would have enough oomph, it might
03:34 PM Gerhard is now known as Guest84692
03:36 PM enleth: oh, interesting, some people are turning chinese mini-mills into surface grinders
03:37 PM cpresser: enleth: pics or it didnt happen
03:38 PM enleth: https://i.pinimg.com/originals/f3/95/91/f3959124983bd98cb51e983bca407fea.jpg
03:39 PM Guest84692: hi. is there a way to set different steplengths for each axes in the .hal-file ?
03:39 PM enleth: this is obviously a Sieg or something very similar
03:40 PM enleth: this actually looks like something I need https://www.alibaba.com/product-detail/benchtop-surface-grinder_1865341387.html
03:41 PM enleth: I wonder, how likely it is to be a complete piece of shit
03:43 PM XXCoder: you'll probably need to rebuild it
03:43 PM XXCoder: after that probably fine?
03:48 PM enleth: not a bad price for a kit, if the castings are machined semi-decently
03:48 PM gregcnc: there was a milwaukee delta of that size
03:49 PM gloops: Guest84692 steplen
03:49 PM enleth: still, I'd be happier to get one of those vintage benchtop grinders that no one sells in my area
03:50 PM gloops: http://wiki.linuxcnc.org/cgi-bin/wiki.pl?TweakingSoftwareStepGeneration
03:50 PM Roguish_shop: hazzy-dev: .. all depends on the budget.....and expectations.
03:51 PM gloops: https://www.ebay.co.uk/itm/Surface-Grinder/123198453084?
03:51 PM enleth: ugh, local resellers have this chinese unit - for ~$3200
03:51 PM Guest84692: gloops: i changed the values of steplen in the .hal but without any effect.
03:52 PM gloops: Guest84692 you are saving and restarting linuxcnc after a change?
03:54 PM Guest84692: gloops: yes i think so. i am not at the machine at the moment. i tried the stepconf and checked the hal - file. steplen is always only between 0 and 1, never the 6500 ns i would need on one axe.
03:54 PM gloops: this is relative to BASE PERIOD and so on, you need to get your head round how it works, bit of reading and so on, im not really in a position to explain atm
04:00 PM pcw_home: If you use stepgens reset option the steplength value is usually just set to 1
04:01 PM Guest84692: gloops. the page you mentioned seems to help. thanks.
04:22 PM unterhausen: gfci breaker blew, there is a hipot failure between hot and ground
04:22 PM unterhausen: I think I know where, going to be a pain to fix
04:57 PM Tecan: http://www.netpipe.ca/zen/3D-Printing/bridge.png http://www.netpipe.ca/zen/3D-Printing/bridge.jpg , 10 inch string of pla from my part after it was done.... i gotta learn to be able to do that
04:59 PM gloops: theres some pro 3d printing people in here Tecan
04:59 PM gloops: just catching them around
05:00 PM Tecan: 10" bridges are unherd of i thought
05:00 PM Tecan: i wonder how reliable it can be done
05:03 PM gloops: that looks like a beer pump
05:35 PM Deejay: gn8
06:21 PM Lcvette: pcw_home: tried the setting changes they suggested but not really any improvement over the previous drive plots
06:22 PM Lcvette: One thing i have noticed is in feedback mode this thing really has some buzz and hum now from the motors
06:22 PM Lcvette: Table even vibrates
06:22 PM Lcvette: I tried changing settings to get rid of it but could figure out what was causing it
06:23 PM Tom_itx: too much P?
06:23 PM Tom_itx: and or D
06:23 PM Lcvette: Lowered P
06:23 PM Lcvette: Didn't help much
06:23 PM Tom_itx: it's crossing the setpoint apparently
06:23 PM Tom_itx: causing the noise
06:24 PM Lcvette: Tried removing d lowering d raising d
06:24 PM Lcvette: I tried several things in strategic order so i as not to overlook anything
06:25 PM Tom_itx: just remember what your "best" one was
06:26 PM Lcvette: Wondering if velocity mode would also have that?
06:40 PM andypugh: You could try setting a small deadband in the PID
07:35 PM enleth: eh, finally managed to understand how the Celtic's feed gearbox works
07:35 PM enleth: https://hackerspace.pl/~enleth/celtic-feed-gearbox.pdf this schematic is horrible
07:36 PM enleth: someone tried to draw a kinda-sorta-planar projection of a set of four gear shafts that are anything but in a single plane
07:37 PM enleth: the first stage looks fine, the second stage is kinda iffy but readable
07:38 PM enleth: but the last stage where feed reverse happens is drawn in a way that doesn't hint in any way as to what meshes with what
07:41 PM enleth: the side view in the lower right corner shows the actual relative positions of the shafts (I, II, III, V - no idea what happened to IV, it's nowhere to be seen)
07:42 PM enleth: II and V are actually permanently geared together even though they're not adjacent on the projection at all
07:44 PM enleth: I can see how this lathe was considered "cool but overengineered" when it was introduced
08:03 PM SpeedEvil is now known as Guest49805
08:50 PM Tom_itx is now known as Tom_L
09:16 PM Tom_itx: https://www.mmsonline.com/articles/a-new-milling-101-milling-forces-and-formulas
09:16 PM Tom_itx: haven't found part 3 but that set is fairly interesting
10:28 PM Lcvette: I spent the afternoon reading about velocity, position and torque control and it appears to have many varying opinions on which method is best to use for machines
10:29 PM Tom_L: the very best one is the one that works best for you
10:30 PM Lcvette: Seems position control is ideal for robot arms and velocity control used to be the primary control method for machining centers but that has gravitated towards torque control or a combination of two of the control types blended by internal switching
10:31 PM Lcvette: Well position control does not seem near as smooth
10:32 PM Lcvette: Feedback control actually
10:33 PM Lcvette: With position
10:35 PM Lcvette: This does track with what I've read
10:36 PM pcw_home: All CNC/Robotic systems use position control (there is always position feedback) how this is partitioned between drives and controller varies by system
10:36 PM Lcvette: I read velocity with feedback control is speed be smoother in motion
10:36 PM pcw_home: there are no velocity only CNC systems
10:37 PM pcw_home: there is always position feedback
10:37 PM Lcvette: I understand I'm referring to the control your
10:37 PM Lcvette: Type
10:38 PM pcw_home: a typical control system has 3 nested loops (position --> velocity --> torque)
10:38 PM Lcvette: That's what i was reading
10:39 PM pcw_home: This is nearly universal
10:40 PM Lcvette: I was reading that each of those methods have different characteristics
10:41 PM pcw_home: Each loop is different but the total systems end up the same
10:41 PM pcw_home: +- how well each part is done
10:43 PM pcw_home: that is you cannot have a CNC system with servos without position feedback
10:43 PM Lcvette: Of course
10:44 PM Lcvette: Or there would be no loop
10:44 PM pcw_home: that feedback may be in the drives or in the controller (same math applies +- loop rates etc)
10:45 PM Lcvette: I completely comprehend this
10:45 PM Lcvette: The methods internally were fuzzy
10:46 PM Lcvette: The velocity, torque, position method of control
10:46 PM Lcvette: How they differed from each other
10:47 PM pcw_home: They are all there in a typical system
10:47 PM Lcvette: True
10:48 PM pcw_home: Different partitioning may convey advantages on simple system with full drive communication to the host
10:48 PM pcw_home: s/with/without/
10:49 PM Lcvette: So you don't think it will make any difference?
10:49 PM pcw_home: for example if you wanted to limit torque while homing (or measure torque required for maintenance reasons) you might want a torque controlled drive
10:52 PM Tom_L: is modbus pretty generic or model specific for control?
10:52 PM pcw_home: If you change the drive mode, it will change the tuning and might move parts of the loop to the host that may information the the drive doesn't have
10:52 PM pcw_home: s/may/may have/
10:53 PM pcw_home: s/the the/that the/
10:54 PM Lcvette: Not sure i follow
10:55 PM Lcvette: I assumed it would be returning from scratch starting with the drive itself and it's following error and drive settings in open loop
10:56 PM Lcvette: Do you mean it would require different Hal config?
10:58 PM pcw_home: If you setup the drive for velocity mode, the hal tuning would be somewhat different
10:59 PM pcw_home: if you setup the drive for torque mode, the hal tuning would be very different and would likely require 2 nested loops
10:59 PM Lcvette: stepgen has two control modes, which can be selected on a channel by channel basis using ctrl_type. Possible values are "p" for position control, and "v" for velocity control.
10:59 PM pcw_home: (velocity and position)
11:00 PM Lcvette: That's what i was researching earlier
11:00 PM Lcvette: Trying my hardest to learn
11:00 PM pcw_home: yes its identical to a servo drive (in position mode the stepgen has its own position loop)
11:01 PM pcw_home: (embedded in the driver)
11:01 PM Lcvette: So i was leaning towards velocity mode
11:02 PM pcw_home: at its base, the stepgen is a velocity controlled device
11:03 PM pcw_home: as its base, a servo drive is a torque controlled device (though the torque control loop is almost always in the drive)
11:04 PM pcw_home: ( The stepgen is "massless", a servo motor rotor is not )
11:05 PM Lcvette: By the way.. short vid from just after the drive tuning but before going closed loop, everything was silky smooth
11:05 PM Lcvette: https://youtu.be/sRoxu4CiuaM
11:05 PM Tom_L: pcw_home would the pwmgen drive your little analog +- converter?
11:05 PM Lcvette: Yes, that's a good point
11:06 PM pcw_home: silky smooth and inaccurate are easy...
11:07 PM pcw_home: just lower the gain and put a lowpass filter on the command...
11:07 PM Lcvette: That was open loop with the .08mm ferror
11:09 PM pcw_home: What well its still closed loop but only locally at the drive
11:10 PM pcw_home: what was the error with closed loop? (it seemed negligible except for jerk peaks)
11:10 PM pcw_home: Tom_L: yes its PWM+DIR
11:11 PM Lcvette: The jerks at worst peak at rapid were .02mm
11:12 PM pcw_home: So whats the issue with closed loop?
11:12 PM Lcvette: At cutting speed of 5000mm/m it was around 0.015mm
11:13 PM Lcvette: And 0.0003mm everywhere flat
11:13 PM Lcvette: Not smooth
11:13 PM Lcvette: Vibrates
11:13 PM Lcvette: Noi
11:13 PM Lcvette: Noisy
11:13 PM Lcvette: Sounded harsh
11:14 PM Lcvette: Only when in closed loop
11:14 PM pcw_home: well the higher the loop gain, the crunchier it will be
11:14 PM Lcvette: Read as to controller
11:14 PM Lcvette: Yeah
11:15 PM pcw_home: noisy when in motion or idle?
11:15 PM Lcvette: Both
11:16 PM pcw_home: dithering when idle can often be eliminated with a small deadzone
11:16 PM Lcvette: Yeah i saw Andy post about that
11:17 PM pcw_home: Higher gains and more accuracy will result in more noise
11:19 PM Lcvette: What you said earlier about a lowpass filter
11:19 PM Lcvette: Is that something you think i need?
11:19 PM Lcvette: Or that would help?
11:19 PM Lcvette: Thought filters were bad?
11:20 PM pcw_home: some noise may be the result from the drives electronic gearing (which will likely cause a beat if it is not a straight multiple/ divide of the encoder signals)
11:21 PM pcw_home: yes filters in the command will reduce accuracy (increase following error)
11:21 PM pcw_home: but probably make it quieter
11:22 PM Lcvette: I tried removing the eg
11:23 PM pcw_home: you can probably also make it quieter by lowering LinuxCNCs P term (and lower accuracy at the same time)
11:23 PM Lcvette: Linuxcnc gave me a message saying my sett
11:24 PM Lcvette: Settings were too high fo
11:24 PM Lcvette: For the new stepdcale
11:24 PM Lcvette: 3333.33
11:24 PM Lcvette: So i changed it back
11:24 PM Lcvette: I tried going down on P
11:25 PM Lcvette: Didn't seem to have much effect
11:25 PM pcw_home: The message means you cannot generate pulses that fast with your current steplength and stepspace
11:26 PM pcw_home: if those values are minimum for you stepgen, the drive cannot be run at the requested speeds with that high of a step/mm scale
11:27 PM pcw_home: P will have an effect (in fact if you set P (and D)to 0 you are completely open loop = encoder is ignored)
11:28 PM Lcvette: So i need to make a change
11:28 PM pcw_home: I would also not use any D as it will cause noise and will not help much if any
11:28 PM Lcvette: Maybe that's part of where my problem is stemming from?
11:29 PM Lcvette: I pulled it out
11:29 PM pcw_home: yeah if you have D, drop it
11:31 PM Lcvette: So on the steplength and stepspace
11:31 PM Tom_L: pcw_home are the +-10 reference voltages built in the 7i33/7i33TA ?
11:31 PM Tom_L: i could use a single channel of that to control it probably
11:31 PM pcw_home: ISTR you hall file had 1 usec for steplength and stepspace this would limit you to 500 KHz or 150 mm/sec at 3333.333 steps/mm
11:32 PM pcw_home: No, the 7I33 has a +5V reference
11:33 PM pcw_home: (mult by 2 by the opamp filter/buffer)
11:33 PM Tom_L: do i need to supply the +-10v to the board is what i'm asking i guess
11:34 PM Lcvette: So i would need 2usec for 300mm/sec
11:35 PM Lcvette: Would that be ok?
11:35 PM pcw_home: no you would need .5 usec each (or 1 usec total) and actually a bit less since the stepgen needs some headroom
11:37 PM pcw_home: Tom_L: assuming it works you could also have a single (floating) 20V supply (the device has a built in 1/2 way up virtual ground generator)
11:37 PM pcw_home: untested...
11:38 PM pcw_home: sleepy time for old guys...
11:38 PM pcw_home: bbl
11:38 PM Lcvette: Night Peter!! Thanks as always!!