#qi-hardware IRC log for Tuesday, 2014-07-08

DocScrutinizer05poatao salad05:59
whitequarkadded capacitors. X/Y used to have small deviation, somewhere around ±0.06mm--accumulated, this actually probably fucked up my holes on PCB!--that has now completely disappeared08:21
whitequarkI can touch off, make some rapids, then probe it back and go to 0.00008:21
whitequarkmaybe 0.000±0.005, which is really good08:21
whitequark5 micron!08:21
whitequark(though there's some unknown measurement accuracy in action)08:22
whitequarkbut with Z it didn't work... I wonder why08:22
whitequarkso, swapped X/Z, Z is still imprecise08:59
whitequarkthe problem is therefore not electronics, but mechanics or configuration...08:59
DocScrutinizer05I guess your spindle motor is too heavy for the stepper09:04
DocScrutinizer05you could attach a simple counterweight09:05
DocScrutinizer05string and wheel09:06
DocScrutinizer05maybe 2 wheels09:06
DocScrutinizer05this paired with an assumption in software or by operator that Z-up can get done at max speed, will result in steps skipped09:08
DocScrutinizer05(this == too heavy)09:09
DocScrutinizer05whitequark: maybe when you reduce ramp-up speed for Z-up and also reduce max speed for the same movement, you might already be fine09:13
DocScrutinizer05ramp-up is relevant from spindle motor introduced inertia09:14
DocScrutinizer05max speed is relevant since torque force of stepper motors significantly goes down with increased speed and you need a clearly defined force to make the spindle motor come up09:15
DocScrutinizer05clearly define *minimum* force09:16
DocScrutinizer05if the motor power gets near that needed force, odds are steps are skipped on uniform high speed as well09:17
DocScrutinizer05but more likely is losing steps on ramp-up09:17
DocScrutinizer05spindle motor inertia is a significant component to consider09:18
DocScrutinizer05for inertia also no counterweight will really help - of course it can take away the mere weight and thus the inertia alone may be small enough a force for stepper to handle it correctly09:20
DocScrutinizer05but then counterweight effectively doubles inertia of the system09:21
DocScrutinizer05btw you know how to calibrate spindle motor fixture so it's 100% perpendicular to your table resp PCB surface?09:28
DocScrutinizer05you use a hole saw alike toolbit of some cm radius and check which side it touches your PCB surface first when you go Z-down slowly with running spindle motor09:29
DocScrutinizer05since there are basically zilch requirements for the "hole saw" toolbit, you can build it by yourself09:33
DocScrutinizer05an acrylic disc with one center hole for mounting an axis and a pin attached to the perimeter somewhere to make the "tool" scratch the PCB surface09:34
whitequarkthe table is pretty parallel already09:36
whitequarkhrm, I wonder if microstepping on Z should be turned off10:00
whitequarksince it greatly lowers max torque, probably yes10:01
hozerthe potato salad guy is going to spend $100 on potatoes and $25,000 on fines to the FDA for being an unlicensed food manufacturer :P15:07
whitequarkswapped X/Z motors, now Z skips steps so hard, I can see it and hear it15:08
whitequarkI don't even15:09
hozerwhat are you building15:10
whitequarkI'm not building, I'm fixing my CNC machine15:10
whitequarkCNC mill even15:10
wpwrakhozer: you mean that's the fines before his potatoes even leave the country ? ;-)15:11
hozerno, the state :P15:12
hozerpotatoes as 'product of the farm' are fine. But if you process them, and ship across state lines, the FDA makes a headache15:12
hozerso what about the vocore (rt5350) http://vonger.cn/ and https://www.indiegogo.com/projects/vocore-a-coin-sized-linux-computer-with-wifi15:21
whitequarkhm, the X motor continues to heat up. so the X channel in electronics is somehow busted15:22
whitequarkthough it doesn't appear to have worse effect than just a motor heating up15:22
hozershorted drive fet?15:22
hozerh-bridge fet, maybe?15:22
whitequarkhozer: it's a driver IC, TB656015:22
whitequarkwhich does implement an h-bridge indeed15:23
whitequarkI guess I could resolder the IC...15:24
hozerthis is interesting.. http://www.homediystuff.com/fixing-a-chinese-made-cnc-stepper-motor-driver-board-tb6560-chips/15:25
hozersomeday I am going to build an open-source silicon motor driver chip15:25
whitequarkoh yes, I've read people following his advice15:26
whitequarkbut it doesn't quite seem to be right in my case, I clearly have some mechanical trouble here15:26
Action: whitequark pulls out a bunch of hair from the leadscrew15:27
whitequarkokay, that might have been it15:27
hozerdo you have cats15:27
whitequarkmy hair.15:36
hozerso do you think a vocore-like thing with a power-over-ethernet port and a stepper driver IC would be a good kickstarter?15:37
whitequarkjust install linuxcnc on beaglebone and you're done15:38
whitequarkplug into literally any lpt cnc control box on market15:38
hozerI want to have the linux-cpu on the same board as the CNC control box15:38
whitequarkso you could fry two at once? good idea15:38
whitequarkand you WILL fry the CNC drivers15:39
whitequarkor you'll want to upgrade15:39
hozerthe idea is you have a power-over-ethernet CNC driver15:39
whitequarkyou want to power CNC via PoE?15:39
hozereach motor has it's own dedicated driver board15:39
whitequarkthat's the most ridiculous idea I've heard in a while15:40
hozerwhy so15:40
whitequarkmy terribly underpowered CNC eats 50W just for motors15:40
whitequarkand 200W more for spindle15:40
hozer50w per stepper?15:40
whitequark50W per three steppers15:40
whitequarkbut it's actually rather low, I'd like to have steppers with higher torque so I could do microstepping15:41
hozerwell, I would not try to drive the main spindle with POE (although I have seen a 200W POE converter)15:41
whitequarkso PoE delivers 25.5W max15:41
whitequarkper cable15:41
whitequarkdo you intend to make a CNC mill for ants?15:42
hozerone cable per stepper, so you'd have a 75w power budget for 3 motors15:42
whitequarkthat's idiotic15:43
hozerrealistically, what I'd want is something that can do say 4inx4in milling out of a pcb15:43
hozerwell the only way I'm going to find out how idiotic it is will be to build it15:44
whitequarkyeah, but don't put it on kickstarter. you're free to suffer the consequences of your own bad decisions, but dragging everyone else is plain malicious.15:45
hozerhow's that different than the vocore/rt5350 ;)15:46
hozerif some guy can do potato salad I should be able to do ethernet steppers15:46
whitequarkdid you deliberately combine the worst possible ideas in order to parody kickstarter crap?15:47
whitequarkif yes, congratulations. if no and you mean this seriously, I'm sorry15:47
hozerand no, I'm not going to put this on kickstarter, until I have something running because nobody will believe it until I have video and schematics showing it running15:49
hozerand if there's something wrong with the rt5350, please tell me know before I waste a lot of time on it15:50
whitequarkhm, so15:53
whitequarkballscrew assembly is fucked15:53
whitequarkI rotate it by hand and while going down, it blatantly skips steps15:54
whitequarkthis has been masked by the Z stepper mount, which actually put the entire weight of spindle on the Z stepper axle and stepper mount!15:54
whitequarkhozer: don't forget to share the ground of rt5350 and the stepper drivers, this is absolutely crucial to success15:59
hozeryou joke about that but it may be necessary for thermal management :P16:01
hozernot that I'm going to try that on rev0.1 though16:01
hozerbut to make this work I need a working board with just some ethernet-capable chip in KiCad to start breaking16:04
hozerooooooohhhh, you know what would be even better than a stepper... a Tesla coil!!!16:05
hozerback to thermals though, has anyone talked about how you'd integrate thermal modeling with KiCad?16:06
whitequarkI have sheared a screw while trying to disassemble the spindle mount :/16:10
whitequarkor maybe it already was sheared16:10
whitequarkwhat the *fuck*16:13
whitequarkthe screw surfaces don't match and whatever is screwed there is actually a non-sheared screw16:13
whitequarkso basically they fucked up and then covered their mistake with a slightly bigger screw that doesn't actually fix anything16:14
whitequarkI'm *so* going to complain16:14
wpwrak(underpowered) well, for example my MDX-15 is WAY weaker than your machine. still sufficient for PCBs and acrylic16:23
whitequarkI wanna aluminium and mild steel and copper...16:23
whitequarkargh. screwed out that stub. yeah, it's a completely new non-sheared16:23
wpwraki can do Al, but veeerry sloooowly :)16:23
whitequarkscrew one mm bigger.16:23
whitequarkwpwrak: actually that probably means that you don't, or rather don't do it well16:24
whitequarkbecause the tool rubs Al and it sticks to the tool, quickly destroying it16:24
whitequarkwhat is "quickly" may vary. but chances are that you can make 5 parts before it breaks rather than 500.16:24
wpwraki use oil to help with that16:24
whitequarkI see16:24
wpwraksmall quantities :)16:26
whitequarkit is not actually a ballscrew16:28
whitequarkit is just some threads in aluminium16:28
whitequarkwell, that explains the poor Z accuracy I had earlier. the reason is, plain and simple, backlash16:29
wpwrakwhitequark discovers the ancient asian secrets of low-cost design ;-)16:29
whitequarkwait no, it's not even aluminium16:31
whitequarkit is... PTFE?!!!16:31
whitequarkalso apparently the jerky motion is due to linear bearings sticking to the shaft16:34
whitequarkdo you in general oil linear bearings? they don't seem to have any16:34
whitequarkwtf, they didn't lubricate the linear bearings at all17:49
whitequarkand the balls have made a groove in the rails17:49
wpwrak"pigfucker", russian expression of respect and admiration, directed towards a culturally, socially, and intellectually superior master craftsman20:49
wpwrakmeanwhile, i wonder what is happening in belo horizonte ...20:50
larscI'm wondering what is happening outside20:52
wpwrakgermany vs. brazil is currently 5:020:52
zrafawpwrak: in belo horizonte there is just mourn20:52
zrafawpwrak: I just hope we win tomorrow and wolfspraul does not watch a possible match arg-ger20:54
wpwrakzrafa: remember wolfgang's visit ?20:54
wpwrakah yes, you do :)20:54
zrafawpwrak: I will not forget that for sure20:54
zrafawpwrak: for ever in my mind.. that match was similar to the today's20:55
zrafafor brazil20:55
wpwrakwe MUST win tomorrow. revenge for the 3rd of july 2010 is near ...20:55
wolfspraulzrafa: hey everybody!21:05
wolfspraulof course I'm watching21:05
wolfspraultoo bad cannot repeat the asado on werner's rooftop21:05
wpwrakhe's alive !!! :)21:05
wpwrakwolfspraul: welcome back ! :)21:06
wolfspraulalways here21:06
wolfspraulI keep the server running21:06
wolfspraul5:0 what is that?21:06
wolfspraulhas the NSA hacked the stream?21:06
wpwrakzrafa: so you were right - he's watching ... and 5:021:06
zrafawpwrak: hey!21:08
zrafawolfspraul: hey21:08
zrafawolfspraul: we can repeat the asado on werner's.. but without matches arg-germ21:08
wpwrakand maybe when it's a little bit warmer. these days it's still a bit chilly.21:09
wpwrakwolfspraul: how's life treating you these days ? still in china ?21:10
zrafawolfspraul: germany is winning the today's match 5:0 to brazil21:10
zrafawolfspraul: ah.. you are watching as well21:10
wolfspraulwpwrak: life is good, thanks!21:14
DocScrutinizer05hi wolfgang!21:14
wolfspraulDocScrutinizer05: hi!21:24
DocScrutinizer05what been the bet? 8:1?21:25
DocScrutinizer05might pan out21:25
wolfspraulthe nsa inserted another goal into my stream21:25
DocScrutinizer05nah, they already control the matrix21:26
DocScrutinizer05does it take a few minutes still?21:35
wpwrakwell, the 8 seems quite possible. how things are going, i wouldn't be so sure about the 1, though ...21:35
DocScrutinizer05yeah, needs a tad more effort from Brasilians to reach the :121:39
DocScrutinizer05maybe somebody in German defense helps a bit? ;-)21:39
DocScrutinizer05or Neuer goes pissing21:41
DocScrutinizer05or has a hotdog21:41
DocScrutinizer05or phones his wife21:41
DocScrutinizer05no way there will be a :121:44
pcercueiS2a 8: maybe :)21:45
DocScrutinizer05WTF! they made it!21:46
DocScrutinizer05now the 8: please!!!21:46
wpwrakat least a little less embarrassing21:47
DocScrutinizer05yes, I been hoping for that very much. Don't want to see them getting shot by their "fans"21:49
wpwrakto add injury to insult, they'll have to play once again, for 3rd and 4th place21:49
DocScrutinizer05otherwise they could hide in some cave for the next 2 years21:50
DocScrutinizer05but now they actually might get shot21:50
DocScrutinizer05I guess whole Brasilia is quite shocked, desperate and angry now21:51
wpwraki guess it would have been better to lose against colombia ...21:55

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