#linuxcnc Logs
Jan 02 2019
#linuxcnc Calendar
01:37 AM Loetmichel: mornin'!
01:41 AM XXCoder: morning
02:14 AM Deejay: moin
03:09 AM gloops: right, just a couple of bandsaw blade guides to design and make
04:50 AM jthornton: morning
04:51 AM XXCoder: hey jt
05:10 AM Tom_L: morning
05:11 AM XXCoder: yo
05:13 AM Tom_L: 22°F Hi 37
05:13 AM XXCoder: 31f
05:13 AM XXCoder: been freezing last 2 days but today is last day
05:13 AM XXCoder: rest of it all low 40s f and rain
05:13 AM XXCoder: its been clear/cloudy 3 days. wow land got dry!
06:27 AM veek: could you use a 5-8 ton jack to make stampings? Transformer and such? from rolled steel.. would the pressure be enough to punch the metal
06:29 AM Loetmichel: depends on the size
06:30 AM Loetmichel: also on the material thickness
06:30 AM Loetmichel: but trasnformer cores are made of soft iron. not steel
06:30 AM Loetmichel: steel doesent work that well there
06:30 AM veek: CRGO?
06:31 AM syyl: there are basic formulas to calculate the forces for stamping
06:31 AM syyl: you need the circumference of the shape you want to cut out
06:31 AM syyl: and material / thickness
06:32 AM veek: well small stampings.. the size of a 250V 24v transformer at 5A
06:32 AM Loetmichel: veek: usually iron with up to 3% Si
06:33 AM syyl: ah sorry, not circumference, its actually the surfacearea of your part
06:33 AM Loetmichel: yes, CRGO
06:34 AM syyl: force(N) = partarea(mm^2) * 0,8 * Rmax(N/mm^2)
06:34 AM veek: i'm trying to figure out if the 5-8 ton jack will do or if i need a 50 ton jack..
06:35 AM syyl: http://www.wisetool.com/formular/formula.htm
06:35 AM syyl: theres your formulas :D
06:35 AM Loetmichel: syyl: ahem: no material thickness in that formula?
06:35 AM Loetmichel: HOW?
06:35 AM veek: what Rmax
06:36 AM syyl: tensile strength of your material
06:36 AM syyl: material thickness comes into play when calculating the shear-work
06:37 AM Loetmichel: really? interesting
06:38 AM syyl: i didnt invent those formulas ;)
06:38 AM Loetmichel: gut feeling was that you need a LOT more force to punch something out of 10mil steel then out of 0.5mm steel
06:39 AM syyl: thats what i would expect too ;)
06:39 AM gloops: hmm i looked into this years ago for coin making
06:39 AM gloops: cant remember a bloody thing though
06:39 AM gloops: thing is, striking a coin is a whole different ball game to pressing a coin
06:39 AM veek: https://www.machinemfg.com/punching-tonnage-calculation/
06:40 AM gloops: hammer = shock loading, press does not, a lot more relative force needed
06:42 AM Loetmichel: our local sheet metal guy has a Trumpf CNC punch... with a hadraulic pressure gauge... you can barely see the needle move on 1mm galvanized... same punch tool in 6mm and the needle does a 270° every punch... and you feel that in the whole workshop in your feet
06:43 AM Loetmichel: -a+y
06:44 AM veek: what books would cover this topic?
06:44 AM veek: tool and die making?
06:45 AM syyl: yes, any book on tool/die design
06:45 AM syyl: probably machinists handbook has some basics
06:48 AM gloops: 'the art of medieval coin striking' by Olaf Brasssunn
06:48 AM veek: ah thanks :)
06:49 AM veek: darn you broke google - that brings up nothing
06:49 AM Loetmichel: veek: btw, as a rough guideline: said CNC punch can do a maximum of 6mm mild steel with the largest tool about 30*5mm... and that thing can press 20 tons
06:49 AM gloops: very rare book
06:50 AM syyl: my gut feeling tells me that you will make only transformers for ants with 5tons ;)
06:51 AM veek: Loetmichel, hmm i don't get it.. who only 20T? don't car jacks lift 50T? there's one selling for like $100-200???Torin Big Red Hydraulic Bottle Jack, 50 Ton Capacity
06:52 AM veek: s/who/why
06:52 AM syyl: a 20t press that can do 1 stroke a second or faster is a complete different beast to a jack that does 50ton very slowly
06:52 AM Loetmichel: syyl: wouldnt say that. i would say with 5 ton he can maybe do about 100*100mm cores out of 0,5mm "elektroblech"
06:52 AM veek: syll ah okay
06:52 AM Loetmichel: if he has a tool with very small "schnittspalt"
06:52 AM Loetmichel: veek: a cnc punch usually doesent do a whole part
06:53 AM syyl: 100x100, no way with a flat faced punch and single digit tonnage ;)
06:53 AM Loetmichel: it has small "cutters" and round punches and "nibbles" the countour out
06:53 AM Loetmichel: and does that MANY times a second
06:53 AM gloops: for diy i mean what you want is a die holder, put the blank under punch, then whack it with a sledgehammer
06:54 AM gloops: 50 ton shock
06:54 AM Loetmichel: it does our 1.5mm aluminium sheet PC front doors... 100s of 3mm holes. literally in less than a minute:
06:54 AM gloops: to recreate that you need some very quick pneumatic ram or something, far more involved
06:54 AM Loetmichel: http://www.cyrom.org/palbum/main.php?g2_itemId=16940
06:54 AM Loetmichel: these
06:55 AM veek: gloops, how would i make the die.. i'm a total noob at this
06:55 AM gloops: assuming you havent got a cnc mill - die grinder
06:55 AM veek: ah die grinder I can afford!
06:55 AM gloops: but even then..thats some work for a coin with lettering etc
06:55 AM syyl: probably machine it out of toolsteel, harden and grind it
06:55 AM gloops: incredibly fine work
06:56 AM syyl: and then you need to make the die plate with the negativ cutout of your die too
06:56 AM gloops: right
06:56 AM syyl: with a fairly precise gap between die / die plate
06:56 AM syyl: depends on your material thickness
06:56 AM veek: isn't there a gentle introduction to all this.. like a book..
06:56 AM Loetmichel: sync: and a "growing" hole in the bottom ;)
06:57 AM syyl: any book on tool&die design
06:57 AM gloops: there were tutorials online when i looked, 10 years or more ago, we struck some coins in the Jorvik centre at York, got interested
06:57 AM Loetmichel: veek: have you considered milling those cores?
06:58 AM veek: Loetmichel, i don't have a milling machine
06:58 AM Loetmichel: could be cheaper and more flexible than a punch die
06:58 AM syyl: have them lasercut
06:58 AM veek: actually i don't even own an angle grinder.. (just to be clear)
06:58 AM Loetmichel: syyl: IIRC lasercutting electro steel means you have to heat treat it afterwards
06:58 AM rmu: this seems more plausible https://www.pass-ag.com/pass-stanzkraftberechnung.html
06:58 AM syyl: not sure, Loetmichel could be
06:59 AM gloops: https://www.youtube.com/watch?v=h0fc2BDEy1I one way
06:59 AM syyl: our laserguy cuts transformer iron for us
07:00 AM gloops: you only need the power to raise the hammer, inertia does the rest, but a sledgehammer is gear to move a lot faster - more shock
07:01 AM Loetmichel: gloops: i wouldnt like to have my fingers under THAT contraption at any given time
07:01 AM gloops: lol, i wouldnt be in the same room Loetmichel
07:02 AM gloops: view of a viking punch there https://www.youtube.com/watch?v=TLhx2ul2BEM
07:02 AM gloops: you just need someone to hold it while you hit it
07:04 AM Loetmichel: gloops: i would have more trust in a person NOT hitting my hands than i would have in that carabiner holding the fall hammer up in the last video .-)
07:05 AM gloops: well the basic setup is ok, make a rigid punch holder, to hold it steady while you apply force - in some way
07:07 AM gloops: back to my own tedious project
07:31 AM The_Ball: Got my first "real" operations on my machine https://studio.youtube.com/video/hY0dUcev8qc
07:36 AM gregcnc: cool https://youtu.be/hY0dUcev8qc
07:48 AM The_Ball: I have a sticky air solenoid valve, so I have to pulse the ATC arm multiple times before it retracts
08:02 AM gloops: veek https://www.youtube.com/watch?v=ZJUAFnqE4eg
08:03 AM gloops: oh hes gone
10:21 AM MacGalempsy: good morning
01:26 PM SpeedEvil is now known as Guest91662
01:36 PM fragalot: anyone here care to weigh in on servo watts VS stepper motor torque? (No idea how the 2 compare)
01:36 PM fragalot: looking for a servo with an equivalent torque of >3Nm
01:39 PM fragalot: Eh I'll just go for closed loop stepper.. RPM is quite low.
01:41 PM gloops: 950w
01:41 PM TurBoss: and $ per W
01:41 PM TurBoss: lol
01:41 PM fragalot: gloops: how'd you get to that number?
01:42 PM gloops: https://www.ebay.co.uk/itm/Delta-CNC-AC-Servo-Motor-Drive-kit-750W-2-39NM-ECMA-C10807RS-ASD-A2-0721-L/121983062230?
01:43 PM gloops: no im wrong lol
01:43 PM gloops: https://www.ebay.co.uk/itm/950W-6NM-Servo-Motor-Driver-1500RPM-220V-Nema52-Encoder-Cable-for-CNC-Router/282811179713?
01:43 PM gloops: or someone is wrong 950w = 6nm according to that
01:44 PM gloops: but 750w = 2.39nm
01:44 PM fragalot: yea i'm just going to get one of those chintsy chinese £90 closed loop stepper kits on fleabay
01:44 PM fragalot: since I have no idea if this is going to work out or not
01:46 PM gloops: whats it for? a lot of people seem to prefer closed steppers to servos anyway
01:46 PM BitEvil: Naively, 1/6 nm@ 1 rev a second is 1W. So, 6NM@1rev a second is 36W, and 950W would be 1500RPM
01:46 PM gloops: yes thats how i got it BitEvil..
01:46 PM BitEvil: You can compute it simply as force*distance = energy
01:47 PM BitEvil: ah
01:47 PM fragalot: gloops: I'm going to ATTEMPT to replace the change gears on my lathe with a DIY electronic equivalent
01:47 PM gloops: i see
01:47 PM fragalot: and I don't really like the overcomplication that the commercial units have
01:48 PM gloops: you do need to achieve quite accurate angle control for thread cutting
01:49 PM fragalot: which is why i'm not bothering with an arduino
01:49 PM gloops: or when i have looked into this, for a wood lathe, its obvious that much better accuracy is require for metal turning, than a stepper and a timing belt
01:49 PM fragalot: but going for an STM32F303K8 which should give me _VERY_ accurate timing
01:49 PM BitEvil: Sodium is a metal too!
01:50 PM BitEvil is now known as SpeedEvil
01:52 PM gloops: im interested in these low melting point allows XXCoder speaks of
01:52 PM gloops: allows = alloys
02:39 PM gloops: prolonged drinking and eating crap is not commensurate with cad drawing
02:49 PM gloops: but what would you make on it https://www.ebay.co.uk/itm/Mini-Watchmaker-Lathe/323631436208?
03:01 PM XXCoder: watch gears maybe heh
03:02 PM gloops: actually doesnt look like it would cut much - pen bodies maybe
03:04 PM XXCoder: watch gears is much smaller
03:04 PM XXCoder: expecially if its for wristwatch
03:05 PM XXCoder: in fact I think I saw similiar setup in arcivist picture
03:06 PM gloops: ive no real application for watch gears heh
03:09 PM XXCoder: 5 euro lol guess nobody wants those nowdays
03:09 PM XXCoder: maybe arcivist but hes not been in here for quite a while
03:11 PM gloops: no tailstock, looks like its been knocked up by someone, still, could be used for something
03:12 PM gloops: motor got to be worth £10
03:13 PM XXCoder: think its commerical product, or in least was
03:13 PM XXCoder: wood board and motor added of course
03:13 PM XXCoder: I guess so guy can move it around
03:14 PM XXCoder: price of less precision but I guess it doesnt affect that much
03:17 PM gloops: i might indulge if it stays for nothing, some slides for something maybe
03:18 PM fragalot: gloops: i wonder what someone would cut on a WATCHmakers lathe. :P
03:18 PM gloops: thats not a watchmakers lathe, too coarse
03:18 PM fragalot: that depends on the size of watches you make
03:19 PM syyl_: a real 6 or 8mm watchmakers lathe will take a suprisingly heavy cut
03:19 PM gloops: difficult to estimate the size, but that chuck and tool
03:19 PM XXCoder: gloop that lathe looks like archivist picture of one, and hes one
03:19 PM syyl_: but that thing in the ebay link looks hacked together
03:20 PM XXCoder: too bad he dont come in anymore
03:20 PM gloops: some of the parts look ill fitting and tool room made to me
03:20 PM gloops: yes archivist helped me with my project
03:20 PM gloops: spindle threaded behind the chuck with some kind of bent shim
03:21 PM syyl_: headstock obviously built from barstock
03:22 PM gloops: if thats how he makes lathes i dont have much faith in his timepieces lol
03:22 PM syyl_: lol :D
03:23 PM XXCoder: lol
03:23 PM XXCoder: well google shows most dont have jaws like that
03:23 PM XXCoder: but similiar has found
03:23 PM syyl_: on a watchmakers lathe you use the chuck basicaly never
03:23 PM XXCoder: https://www.watchrepairtalk.com/applications/core/interface/imageproxy/imageproxy.php?img=https://uploads.tapatalk-cdn.com/20170909/177801f6d2374a80c0fb6a00a9b72ff0.jpg&key=cb93322c46f1b11b61a9a2098665c5f55ab3d4ec3695d35d93a55a2e9fcb4045
03:24 PM syyl_: either collets or faceplate
03:24 PM syyl_: yeah, that a real one
03:24 PM gloops: probably made for some specific little job
03:24 PM syyl_: with a WW-style bed
03:24 PM XXCoder: other one is si,iliar just modified to have jaws. probably modified for non-watch jobs yeah
03:26 PM gloops: yes some of those watch lathes were very nicely made, very expensive for the size too
03:26 PM syyl_: i recently rebuilt one
03:27 PM syyl_: newprice (still made) around 10k eur
03:27 PM syyl_: and i was suprised how shity is was made in some places
03:27 PM gloops: hmm
03:29 PM fragalot: syyl_: say that to clickspring :P
03:29 PM gloops: i think the chuck on that cheap one is probably on a MT
03:29 PM fragalot: (the never using the chuck part)
03:29 PM gloops: so maybe mount a collet chuck on the threads
03:30 PM XXCoder: gloops: if that thing is modified watchmaker lathe, you could unmodify
03:30 PM gloops: i could modify it to be the z axis on a wood lathe
03:31 PM gloops: alu plates £60 - that £10 maybe
03:32 PM gloops: take headstock off, fit spindle clamp to where toolpost is
03:38 PM gloops: hopefully the old maker wont haunt me for dismantling his lathe
03:39 PM XXCoder: lol
03:42 PM gloops: i want to make something along those lines https://ibb.co/d57dVv0
03:42 PM XXCoder: interesting
03:43 PM Deejay: gn8
04:01 PM gloops: was just curious XXCoder - which low melting point metals did you have in mind for casting?
04:01 PM XXCoder: oh nothing specific but theres nice list a second
04:02 PM gloops: just glancing at some, tin is quite low, 230C
04:03 PM XXCoder: cant find
04:04 PM gloops: pewter around the same
04:04 PM gloops: could melt that on electric cooker ring at a guess
04:04 PM XXCoder: ranges I was looking was 100c to 150c
04:05 PM XXCoder: there was fanastic list. oh well. gonna go to work later
04:07 PM gloops: have a nice day
04:23 PM Nick001-Shop: Using m102,m103 to operate a collet. Putting in 2 manual switches,how do I keep them from activating anything while machine is in auto mode?
05:49 PM The_Ball: Is there somewhere where I can see what's coming up in LinuxCNC 2.8?
06:23 PM flyback is now known as star2018
06:23 PM star2018 is now known as flyback
06:26 PM Tom_itx: look at the changelog
06:27 PM jthornton: that won't have what's coming up just past history
06:27 PM Tom_itx: hard to say what somebody may decide to work on
06:28 PM jthornton: aye
06:28 PM Tom_itx: you can tell them you want something and may get a 'do it yourself' reply :)
06:29 PM jthornton: that's how it's done if you want something you do it
06:38 PM MarcelineVQ: Or have a persuasive argument
06:45 PM jthornton: who are you going to argue with?
06:51 PM MarcelineVQ: Well the do it yourself responder, though the ideal order would be to present the persuasive argument before getting the do it yourself response
07:22 PM flyback: dammit
07:22 PM flyback: first superdave osborne dies and now the captain in Captain & Tennille :/
07:32 PM renesis: wtf superdave
07:40 PM flyback: yeah you knwo who that is right?>
07:40 PM * flyback blames HighInBC
07:40 PM flyback: renesis, also mean jean from wwf died
07:40 PM flyback: gene
07:41 PM * flyback blames HighInBC for all 3 celeb deaths today
07:42 PM HighInBC: rule of 3s... keep on my good side
07:42 PM renesis: wtf mean gene, i cant believe i know who you are talking about
07:42 PM renesis: wtf is captain and tennile
07:42 PM flyback: keep us together
07:42 PM flyback: I WILL
07:42 PM flyback: I WILL
07:42 PM flyback: I WILL
07:42 PM flyback: that song ring a bell?
07:43 PM flyback: they used in some recent movie
07:43 PM flyback: OH I KNOW WHAT IT WAS
07:43 PM flyback: THE FINAL EPISODE OF HAVEN ON SYFY
07:44 PM flyback: oh he had parkinsons ouch
07:51 PM MarcelineVQ: superdave? sad news
08:07 PM gloops: cant say ive heard of him
08:07 PM gloops: i heard of superted
08:09 PM norias: hmmm...
08:09 PM norias: i'm seeing some people using brushless dc motors for spindles
08:09 PM norias: is this somehow better or worse than an induction motor?
08:16 PM gloops: i dont know, but ac motors work
08:17 PM norias: oh, for sure
08:17 PM gloops: veek https://www.youtube.com/watch?v=ZJUAFnqE4eg
08:17 PM norias: i'm mostly looking at AC because that's what's on production machines
08:17 PM norias: afaik two speed (star / delta) induction motors
08:17 PM norias: (constant horsepower)
08:17 PM gloops: someone in diycnc was adapting rc dc motors for using as a spindle norias
08:18 PM norias: yes, but i'm not sure why.
08:18 PM gloops: cheaper mainly, also higher speeds, for pcb cutting etc
08:19 PM gloops: 50000 rpm +
08:20 PM norias: i'm surprised it would be cheaper
08:20 PM norias: given the magnets required
08:21 PM norias: maybe they don't need much torque
08:21 PM gloops: im not buying a 3 phase spindle for my next router, im just going to use a .5 hp motor with stepped pulleys to a shaft, i only use 2 or 3 speeds anyway
08:21 PM norias: hmmm. right on.
08:37 PM flyback: YOU KNWO YOU Can make your own 3 phase converter
08:37 PM flyback: also some vfd's do it automatically
08:38 PM norias: what do you mean?
08:44 PM flyback: if you don't have 3 phase power
08:44 PM flyback: you can make a phase converter using 2 motors or get a vfd that does single 3 conversion
09:04 PM veek: norias, using SCR/triac and such (solid state device)
09:05 PM veek: hey gloops, ty :p
09:08 PM norias: yeah, i'll look in to that
09:08 PM norias: right now, i'm working backwards
09:08 PM norias: from some common milling scenarios to generate a horsepower / torque requirement spec for the motor
09:09 PM norias: then see what kind of motors fit that
09:14 PM veek: norias, how are you doing that? working out that power requirements for milling)
09:15 PM norias: uh, rather standard formula
09:15 PM norias: it's in machinery's handbook
09:15 PM norias: i stuck in an excel sheet at some point
09:15 PM veek: oh hmm.. i don;t have enough knowledge to understand the handbook
09:15 PM norias: basically take MRR divided by a "K" factor
09:16 PM norias: which is material dependent
09:16 PM norias: in reality it's material / tool combination dependent
09:16 PM norias: note HP requirements will increase as the edge on the tool wears
09:16 PM norias: but, you can take the K factor from the book
09:16 PM norias: get the HP requiremnet at the tool
09:17 PM norias: then divide by the efficiency of the drive train for the spindle
09:17 PM norias: (another look up in a table thing)
09:17 PM norias: geared systems are less efficient than belts, generally
09:17 PM norias: so belts are like 90%
09:18 PM norias: that gives you the HP at the motor
09:18 PM norias: i use it as a sanity check
09:18 PM veek: hmm won't gears be more efficient.. i thought belts slip?
09:18 PM norias: i.e. can the machine even generate that much power, in theory, for what i want to do
09:18 PM norias: no, actually
09:18 PM norias: belts do slip, but when they don't, they are more efficient
09:19 PM norias: if the belt system is designed right, they won't slip until you get pretty close to the HP max of the motor
09:19 PM norias: in my experience
09:20 PM norias: so, i usually do that and back off to 60% of whatever feed i came up with as using max HP
09:20 PM norias: then creep up to 80% if everything holds
09:20 PM norias: keep in mind, there are a ton of things that can go wrong before you even get to using 80% of HP on production machines
09:21 PM norias: I've done it using ER-32 collets with a torque wrench and ball bearing nuts
09:21 PM norias: which generate a lot more holding force than regular collet nuts
09:21 PM norias: plus, i usually have to have six bolt / clamps on a regular 6" vise
09:23 PM norias: sorry, that was long
09:23 PM norias: i like machining
09:24 PM veek: yeah lot of google involved.. i know what a collet is .. but ER32
09:25 PM norias: ER collets are double angle collets
09:25 PM norias: they have different size ranges
09:25 PM norias: ER 32 goes from.. i think 1/6" to 3/4"