#linuxcnc Logs
Nov 18 2022
#linuxcnc Calendar
12:53 AM -!- #linuxcnc mode set to +v by ChanServ
01:03 AM -!- #linuxcnc mode set to +v by ChanServ
05:33 AM JT-Cave is now known as reporter
05:34 AM reporter is now known as JT-Cave
10:34 AM pere: hi
10:40 AM roguish[m]: hey, anyone here good at sniping on ebay? i need a special graphics card for the wife....
10:50 AM roycroft: i don't know what "good at sniping" means, but i tend to have decent success at it, doing it manually
10:51 AM roycroft: there are software apps that automate the sniping, but i'm not sure they work as well as my manual method
10:52 AM roycroft: my method is to wait until a minute before the end of the auction, and then do a refresh on the bid status, and get a sense of how long the refresh takes
10:52 AM roguish[m]: looking at the automated ones now. what's your manual method?
10:52 AM roycroft: i then put my bid in extimated latency + a tiny bit before the end
10:52 AM Tom_L: you sly dog you
10:52 AM roycroft: i don't know if the automated tools do a latency check
10:53 AM roycroft: my method has a major drawback though:
10:53 AM roycroft: i have to remember to bid
10:54 AM roguish[m]: this one looks good. has lots of referals.... https://bidslammer.com/?source=spencehaw0
10:54 AM roycroft: but when i remember, i usually get a bid in 1-2 seconds before it ends
10:55 AM roycroft: which sniping software pays you a penalty if you lose the auction?
10:55 AM roycroft: that's the one you want
11:17 AM roguish[m]: just created a new ebay account, had to give bidslammer access... it snipes at 10 secs to end.
11:23 AM CaptHindsight[m]: I just had a supplier ask me to send them a CC form over email. They also said that they get cyber security training bi-monthly. :)
11:23 AM CaptHindsight[m]: secure for me but not for thee
11:24 AM CaptHindsight[m]: i guess the training is not working
11:36 AM CaptHindsight[m]: https://www.amazon.com/dp/B0BLXWXSQQ Rpi4 replacement
11:37 AM CaptHindsight[m]: 4GB ram version is only $69
11:38 AM CaptHindsight[m]: easily paired with Mesa or Remora over SPI or Ethernet
12:05 PM CaptHindsight[m]: RTAI kernel 5.4 Debian packages are up!
12:05 PM CaptHindsight[m]: https://github.com/NTULINUX/RTAI/releases/tag/v5.3.3-delta
12:14 PM sensille: is it common to have linear encoders on the axes and do a closed loop that way, instead of using closed loop motors?
12:14 PM sensille: or in addition to?
12:15 PM CaptHindsight[m]: sensille: it depends on how much accuracy you want or need
12:15 PM sensille: so for higher end machines it is done?
12:15 PM CaptHindsight[m]: encoders only on the motors will only give you the exact position of the motors
12:16 PM sensille: i could imagine that a closed loop all the way is much harder to control
12:16 PM CaptHindsight[m]: you can disconnect the motors from the machine and still have the motors position
12:16 PM CaptHindsight[m]: sensille: not really much harder
12:17 PM CaptHindsight[m]: it just has to deal with the delay and play of the mechanical system
12:17 PM sensille: and for encoders you use only glass scales, or also magnetic ones?
12:17 PM CaptHindsight[m]: either
12:18 PM CaptHindsight[m]: it depends on the design
12:19 PM CaptHindsight[m]: glass scales also shrink and grow over temp, mag encoders can have issues with surrounding magnetic fields and chips
12:19 PM sensille: so magnetic tapes can be accurate enough
12:19 PM CaptHindsight[m]: I have had to go as far as adding lasers to movements to account for temp drift
12:19 PM CaptHindsight[m]: sensille: yes
12:19 PM sensille: they're so much cheaper, i was thinking if adding some for fun
12:19 PM sensille: s/if/of
12:20 PM sensille: but yes, chips ...
12:20 PM CaptHindsight[m]: https://www.ligo.caltech.edu/page/what-is-interferometer
12:20 PM sensille: on the other hand, i can only cut al anyway
12:21 PM CaptHindsight[m]: https://www.linearmotiontips.com/where-are-glass-scale-linear-encoders-used/
12:29 PM CaptHindsight[m]: sensille: if you only need 1-2 thousandths of an inch res (25-50) magnetic scales are more than fine
12:29 PM CaptHindsight[m]: (25-50um)
12:30 PM CaptHindsight[m]: sensille: https://www.linearmotiontips.com/how-do-magnetic-linear-encoders-differ-from-optical-versions/
12:32 PM sensille: a while ago i added magnetic tape and sensor chips to my 3d printer, for measurement only. the results were disheartening
12:33 PM CaptHindsight[m]: sensille: did you find out how wobbly they are?
12:33 PM sensille: and racking!
12:34 PM sensille: even though it is corexy, 0.2mm racking
12:34 PM sensille: and backlash
12:34 PM CaptHindsight[m]: don't even try and tell them, they won't listen
12:35 PM CaptHindsight[m]: "but it works, see right here, and it also cuts metals"
12:35 PM sensille: exchanging belts and pulleys with genuine gates helped immensly, but still ...
12:35 PM sensille: hehe, "cuts metals"
02:21 PM Rhine_Labs: Sup all
02:33 PM Guest57: Wow... it's been a LOOOOONG time since i've been on IRC... :)
02:33 PM sensille: ... and IRC is still there, but slowly eroding
02:34 PM sensille: see all the [m] here ...
02:34 PM Guest57: amazing enough that it's still there... don't worry... it'll come back once twitter crumbles (apologies to any twitter employees here - i know you're trying:) )
02:35 PM Guest57: so i do have a topical question...
02:36 PM Guest57: I've been setting up a lathe on linuxcnc (sherline - you do what you can)... but i'm still rather vague about how to set up the axes (the limits specifically) ... and the home location.
02:36 PM Guest57: thotz?
02:38 PM Guest57: i have the steppers configured correctly now... and motion is working well enough for now... but i'm not clear how to establish a proper "starting point" and envelop within which to work.
02:39 PM CaptHindsight[m]: Guest57: limits go on the axis on a place that detects position before it can crash
02:39 PM CaptHindsight[m]: a limit may also be a home
02:39 PM CaptHindsight[m]: a home may also be in the middle
02:39 PM CaptHindsight[m]: is up to you
02:40 PM Guest57: so basically everything else is based on the touch off? (and I don't have limit switches - yet? ... they don't seem common on cnc lathes, small ones anyways)
02:41 PM CaptHindsight[m]: yes it often is
02:41 PM CaptHindsight[m]: using some common sense
02:41 PM Guest57: *shrug* well... guess it's "MOSTLY" working then.
02:41 PM Guest57: oh god no... not THAT!!!
02:41 PM Guest57: "Common sense .... isn't" :)
02:41 PM CaptHindsight[m]: sorry
02:42 PM roycroft: if you're running a bit low on common sense we can sell you some for a reasonable fee
02:42 PM Guest57: shmeh... gettin' there... i have it generating quite acceptable tapers... i'll take it
02:42 PM CaptHindsight[m]: be careful who offers you their common sense
02:42 PM roycroft: well, we can rent you some
02:42 PM Guest57: i'm usually the one supplying it... (my wife calls it "flapping cape syndrome"... yeah, well)
02:43 PM CaptHindsight[m]: it might be hokum
02:43 PM * roycroft is rather uncommon, and is thus unlikely a source of common sense
02:43 PM Guest57: trade fer bzzr.
02:43 PM Guest57: right on
02:43 PM roycroft: but if you might find a weird sense useful, i can probably help
02:44 PM CaptHindsight[m]: roycroft: oh the gas and crime crisis are over now
02:44 PM Guest57: I'll let you know after my machine eats itself... Hell's bells... nothing's worse than the lathe example functions... had to rewrite those so it would stop crashing!
02:44 PM CaptHindsight[m]: now it's two more years of Hunters laptop ending the world as we know it
02:44 PM Guest57: oh that's good to hear... i was worried about gas crimes...
02:45 PM Guest57: (preparing to duck before it get politrical)
02:45 PM * roycroft has had no beans today
02:45 PM CaptHindsight[m]: be wary of an "uncle" that asks you to pull his finger
02:45 PM Guest57: nuh huh.
02:46 PM CaptHindsight[m]: ah no we don't discuss politics or the beliefs of stupid or crazy people in any shape or form
02:47 PM Guest57: I try not to consort with stupid or crazy people at all
02:47 PM CaptHindsight[m]: we don't wish to upset the SCP community
02:47 PM Guest57: ... aaaand so i remain locked in my basement...
02:47 PM roycroft: so you don't live in america, guest57?
02:47 PM CaptHindsight[m]: Guest57: what size mill/router?
02:47 PM Guest57: continental, yes... geopolitical... no.:)
02:48 PM Guest57: it's a sherline lathe for now (i was bored and i got tired of changing gears for threading ... and i needed [ I'm a Canuck
02:48 PM Guest57: ] ... needed parts for a telescope i'm also building )
02:49 PM Guest57: ... but it's just therapy until i build a full size CNC lathe - 3' bed, linear rails, larger spindle
02:50 PM CaptHindsight[m]: as you can see i was paying close attention
02:50 PM CaptHindsight[m]: Guest57: oh we have several of those in here
02:50 PM JT-Shop_ is now known as JT-Shop
02:50 PM Guest57: think - RotarySMP's Schaublin 125, but with linear rails
02:50 PM Guest57: i suspected.
02:51 PM Guest57: the Sherline, as well made and fun as it is, is just WAAAAAY too unstable for anything I want to throw at it.
02:52 PM Guest57: I just took your question as a strategic change of topic :)
02:54 PM CaptHindsight[m]: some conversations get too silly and the chat police show up and shut it down
02:54 PM Guest57: :)
02:55 PM Guest57: ... has anyone used a largeish - let's say, 8-12 N-m closed loop stepper (nema 34) as a lathe spindle drive?
02:55 PM Guest57: trying to decide if it's worth farting with ... i have a couple, but i don't know if it's worth the effort
02:55 PM CaptHindsight[m]: you can but speed limit
02:56 PM CaptHindsight[m]: you mean like cobbling a motor mount, adding a pulley and belt?
02:57 PM Guest57: sortakinda... I have the motor, pulleys and belts - it's not a lot of work to do, but I don't know if it's worth boring out the pulley to the spindle and getting it up and running
02:57 PM CaptHindsight[m]: I would do just that if I was going to make a lathe for threading
02:57 PM Guest57: or does it just stall at any reasonable speed.
02:57 PM CaptHindsight[m]: the noise would bother me
02:58 PM Guest57: Hm... interesting point... hadn't thought of that.
02:58 PM CaptHindsight[m]: waahh, weeee, wahhh
02:58 PM Guest57: yeahhhh they are noisy little jugs
02:58 PM CaptHindsight[m]: but some are winers
02:58 PM CaptHindsight[m]: err whiner
02:58 PM CaptHindsight[m]: some are both
02:59 PM CaptHindsight[m]: but think of the repeatability on a spindle
03:00 PM CaptHindsight[m]: and lots of holding torque at rest
03:00 PM Guest57: that's kinda what I'm thinking... can take lathe and add live tooling / mills (okay, not on the sherline... ... OR CAN I!)... I'm having a Krieger moment... :)
03:00 PM CaptHindsight[m]: oh yeah, 3rd axis fun
03:01 PM Guest57: you could use it for some rather wiggy machining
03:01 PM Guest57: oh fine... i'm going to go try it... wish me lunch.
03:02 PM CaptHindsight[m]: viel Glück
03:02 PM JT-Shop: too late for lunch, be supper time soon
03:03 PM CaptHindsight[m]: never too late for the Bavarian restaurant, al la clown
03:04 PM CaptHindsight[m]: Guest57: what is your other lathe going to be for when it grows up?
03:06 PM CaptHindsight[m]: Guest57: https://www.forum.linuxcnc.org/38-general-linuxcnc-questions/42728-stepper-motor-like-a-spindle
03:25 PM JT-Shop2: in mesact you just select a stepper spindle...
04:57 PM -!- #linuxcnc mode set to +v by ChanServ
05:36 PM -!- #linuxcnc mode set to +v by ChanServ
06:03 PM -!- #linuxcnc mode set to +v by ChanServ
06:17 PM Centurion_Dan1 is now known as Centurion_Dan
06:48 PM Guest57: Hi again...
06:49 PM Guest57: Okay, i'm well and truly... sort of ... stuck... I have a mesa 7i76e running my lathe, and I have two mpg encoder wheels. (quadrature output - six wire... yah)... how do I interface that to the mesa... do you run that through the GPIO inputs?
07:14 PM Guest57: k... think i get it... use the A / B outputs on GPIO and bin the A' and B' ... don't need them...
08:22 PM roycroft: are there any parametric 3d cad geeks about?
08:23 PM roycroft: i'm trying to figure out how to do an assmbly as simply as possible
08:23 PM roycroft: i have two pieces of 1" square tubing, and i need to connect them in a "t"
08:24 PM roycroft: i.e. is connected perpendicular to the other, and centered
08:24 PM roycroft: that's all easy
08:24 PM roycroft: except the cross piece needs to be twisted 45 degrees
08:24 PM roycroft: so i can't do the usual kind of mates to locat it
08:25 PM roycroft: my only solution so far is to create some extra planes at a 45 degree angle to the standard ones, and make mates that are symmetric with those auxiliary planes, but when i start to do that it gets complicated and messy
08:25 PM roycroft: this is with sw 2018, btw
08:26 PM fluffywolf: off-topic, but I don't know where else to ask... can anyone ID this quick-change toolpost? https://imgur.com/a/wMr9oNp
08:26 PM roycroft: and i should say "rotated", not "twisted"
08:27 PM roycroft: that looks shop made to me, fluffywolf
08:28 PM fluffywolf: could be, but it's quite well done if so.
08:28 PM roycroft: shop made decently, or manufactured poorly
08:29 PM fluffywolf: I picked it up at an estate sale for a $50 gamble, as it's about the right size for my lathe/mill combo and had a bunch of toolholders...
08:30 PM roycroft: if it works for you i'd say it was a win
08:31 PM roycroft: there are quite a few tool holders with it, and they are probably worth at least $50 each
08:31 PM fluffywolf: I figured it was a standard design, but I can't find anything like it, which means I'd need to make any more toolholders for it.
08:31 PM fluffywolf: the dovetail is backwards from every single other one I can find.
08:32 PM roycroft: well i'm still voting for shop made
08:32 PM roycroft: but my vote doesn't mean much
08:33 PM fluffywolf: that's certainly an option, but wouldn't most people clone a popular product so they can buy more pieces for it if they're not in the mood to make them? lol
08:33 PM fluffywolf: I mean, that's what I would do...
08:34 PM fluffywolf: that is, even if it's shop made, I would expect it to be interchangable with something else.
08:36 PM fluffywolf: oh well, I'll give up googling for any other toolpost like it.
08:37 PM roycroft: that could be someone's prototype of a product that was going to make them wealthy beyond imagination, but never panned out
08:37 PM roycroft: if you're really curious, do a patent search, and you might find something that was invented but never made it to market
09:33 PM Tom_L: roycroft, edge and angle constraints
09:33 PM Tom_L: or add a center axis to pivot with as i read more...
09:35 PM Tom_L: can't quite picture what you need but maybe a point constraint with 2 angular ones
09:36 PM Tom_L: it should be able to be done without the extra planes but i may need a scribble note to see what you're wanting
09:38 PM Tom_L: you may need a couple more construction lines to work with
09:38 PM xxcodery: is it one peice or assemly of 2 parts?
09:39 PM Tom_L: 2 parts
09:39 PM Tom_L: <roycroft> i'm trying to figure out how to do an assmbly.....
09:39 PM xxcodery: ah yeah
09:40 PM Tom_L: instead of a T, he want's a 45 rotate in one of them at 90 deg in the other plane
09:41 PM Tom_L: so add 2 axis lines for the rotate point and constrain them concentric or whatever it's called..
09:41 PM Tom_L: surface constrain the end to the side
09:42 PM Tom_L: angle constrain the other part
09:43 PM Tom_L: at 45
09:43 PM xxcodery: while im pretty good on designing models, I dont have much experence with assemblies sadly
09:43 PM Tom_L: it's fairly straighforward
09:44 PM xxcodery: cool :)
09:44 PM Tom_L: it might take me a bit since i haven't had cad open in a while now
09:45 PM Tom_L: it also helps to draw the parts where zero x y is the handiest for later use
09:46 PM xxcodery: yeah, I try to do that also when designing
09:46 PM Tom_L: whether it's the center of the tube or a corner etc
09:47 PM xxcodery: if youre curious how I design, I have bunch of freecad files at printables lol (same nick as my normal one here)
09:47 PM xxcodery: im still waiting for my motherboard so still cant fix pc. BAH
09:48 PM Tom_L: and draw the tube with formula so it can be resized and remain centered with one parameter change
09:48 PM Tom_L: i've got loads of files
09:48 PM xxcodery: nice
09:49 PM xxcodery: was you formally trained on modeling?
09:49 PM Tom_L: i took a couple catia classes
09:50 PM Tom_L: i've got 140+ mechanical drawings i can model and have modeled most of them
09:50 PM Tom_L: in catia and sw
09:50 PM Tom_L: but memory fades as time moves on
09:50 PM xxcodery: nice. I had to learn it by mysekf lol. I have pdf models which looks fun but havent worked up to model em due to constant dizzyness
09:52 PM Tom_L: you've seen some of them
09:54 PM roycroft: the sw toolbox doesn't have tubing as small as i'm using
09:54 PM roycroft: i had to draw the tubing from scratch
09:54 PM Tom_L: awww
09:54 PM xxcodery: cant just sketch and exr er yeah lol
09:54 PM Tom_L: http://tom-itx.no-ip.biz:81/~webpage/cnc/practice_drawings/Problem52.jpg
09:54 PM Tom_L: that one was fun
09:54 PM roycroft: i drew the profile centered around 0,0,0
09:54 PM roycroft: and then i extruded it
09:55 PM xxcodery: ouch yeah tom I think its in that pdf also
09:55 PM Tom_L: maybe i know the source of the pdf
09:56 PM xxcodery: likely lol
09:57 PM Tom_L: to be drawn correctly, they had to match the volumetric size
09:58 PM roycroft: one of the problems with what i'm doing is that the tubing is not square
09:58 PM roycroft: i.e. there are not four faces
09:59 PM roycroft: the corners are rounded, so there are actualy eight faces
09:59 PM Tom_L: should make it easier to get the 45
09:59 PM roycroft: and what i need to do is create mates relative to a tangent line on the fillets
09:59 PM roycroft: and sw doesn't seem to have a way to do that
09:59 PM roycroft: if they were chamfered it would be trivial
10:00 PM Tom_L: draw your constuction lines before the fillets X
10:00 PM Tom_L: and use them
10:00 PM xxcodery: you should be yeah like tom said lol
10:00 PM roycroft: i tried creating some tangent construction lines, but sw doesn't let me select a construction line as a mate feature
10:00 PM Tom_L: change them to axis
10:01 PM Tom_L: and try that
10:01 PM roycroft: that is a possibility
10:02 PM * roycroft will try that next time he's in the office
10:02 PM * Tom_L tucks his tired ass into bed
10:03 PM xxcodery: tuck rest of yourself too
11:35 PM Centurion_Dan1 is now known as Centurion_Dan