[Emc-users] Custom kinematics module and changes in Axis GUI [was: Question 3 Axis Machine(w/4 step motors)]
Hello! Let's start with change of the topic - now it should be more appropriate. 2010/6/6 Dave e...@dc9.tzo.com: Something else to consider ... you can make the PyVCP panel a stand alone window. I believe there is a sample config that has that setup. Dave 2010/6/6 Andy Pugh a...@andypugh.fsnet.co.uk: Yes, it is possible. But everything is possible when you have the source code. I don't think that with the standad code the pyVCP can be anywhere other than the right. However, I think you might be able to omit the coolant and spindle pins from the standard HAL file so that the buttons do not appear on the left, and then add buttons with the same functions to a PyVCP on the right. I _think_ but have not checked that you can still access the M3 etc signals through HALUI and direct them to the requisite pins in HAL Thank You, Dave! Actually that might be something easier to implement for what I would like to achieve. I just have to find out, if it is possible to make such a standalone window in a way that user cannot close it - I would like it to be a part of Axis GUI in a way that only way to close my pyVCP window is exiting EMC/closing Axis window. In that case that might work. Andy, I know that I can put pyVCP on the right side, and in my previous e-mail I have attached screenshot of my Axis window. Currently there is a lot of unused space on the left side between axis, spindle and coolant sections and the section, where jog speeds and overrides are indicates. Placing pyvcp on the right side, I will have a panel from the top to bottom of the screen with 2 or 3 buttons and all the rest - again unused space. I prefer the preview window to be as large as possible and also use the remaining space efficiently. I would like to sell the machine, once this conversion is completed, so my interest is making it not only working as good as possible, but also look and feel as user-friendly and convinient as possible. And the setup of GUI screen is one of the parts that a potentian user will have to work with. For example, if you want to change the coolant and spindle buttons to say something else, have a look in src/emc/user_intf/axis/scripts/axis.py for the word spindle in a quoted string somewhere, change it to abrasive rebuild and see if it has worked. (for simplicity I would not suggest changing the variable or label name, just the button text) So thank You for a suggestion on changing the appropriate words in the script of Axis GUI. I will probably install it on another PC and try to play around with it! By the way, a question just came into my mind: Is it possible to copy pyvcp panel code in the axis script so that it gets placed somewhere on the left side of the screen? You might think that this means changing from being a user to being a developer. You would be right, but it's a very fine line with EMC. FWIW I had never programmed in C or compiled anything until a few months ago, and whilst it felt daunting at first, it soon feels perfectly normal to root around in the code. The thing I like most about the EMC is that I as a simple user can make changes to it. I had the situation with my previous controlling system that I was not able to get any information or support from its authors, so now I am delighted that there is a chance for me to adjust it as I want. The problem is that I have no experience in programming and I do not know, where and how to start. That is why I have so many questions - I am trying to understand it. Unfortunately user and integrator's manuals have a drawback that they do explain some technical details, but lack some broader coverage - just like the case of kinematics modules - the way, how to do the calculations and partially also syntax is explained, but - where and how to put that code is not explained. On the other hand, I completely understand, that it is not possible to write a manual that would explain EVERYTHING, so that is why I appreciate having this mailing list - the place for asking questions :)) I feel it not that much as becoming a developer instead of being user, but more like contributing my effort to EMC - I am using this application and I feel that I owe the authors something for using their work. The limiting factor is my lack of knowledge :)) I was thinking and now am willing to ask - what are the options to develop some kind of filter/preprocessor for EMC, in which I would input the tilt angle (B axis) and it could calculate the direction for C axis from X and Y coordinates and then recalculate the same for A and B axis - bit more of trigonometry to get those angles. I think that would be harder than a kinematics module. Finding the instantaneous tangent to a curve in progress is much easier than working it out from the G-code. My own preference (which is irrelevant, as it isn't my machine) would be for a kinematics module that takes X, Y, Z, A where the A is an angle set by the Gcode, but isn't directly
Re: [Emc-users] Custom kinematics module and changes in Axis GUI [was: Question 3 Axis Machine(w/4 step motors)]
On 6 June 2010 10:36, Viesturs Lācis viesturs.la...@gmail.com wrote: Just to make sure that we understand each other correctly - I do not mean usual override that I control a button, which overrides current state of M3/M5 or M8/M9 commands. I would like to make it like a two-level controls - water jet valve gets open only when BOTH of the buttons turn it on - I control one, M3/M5 controls another. Water valve or abrasive valve gets closed as soon as ANY of those buttons are engaged - either I press my button, or EMC receives M5 or M9 command. Yes, that was what I was meaning. If you don't link iocontrol.coolant-flood in the main HAL file then the button won't appear. However the pin still responds to the M8 / M9 commands. If you create a pyvcp panel with a button called abrasive and an LED called abrasive-is-on for example, you can then in your postgui hal file add the following lines. loadrt and2 count=2 addf and2.0 servo-thread addf and2.1 servo-thread net ab-command iocontrol.coolant-flood = and2.0.in0 net ab-interlock pyvcp.abrasive = and2.0.in1 net ab-led and2.0.out = pyvcp.abrasive-is-on parport.0.pin-09-out Should do what you want for one pin. You need to copy the setup and use the and2.1 function for the other. http://www.linuxcnc.org/docview/html//man/man9/and2.9.html Incidentally, your previous query about joint-mode and axis-mode looks to be solvable using the halui.mode.joint, halui.mode.manual etc pins -- atp -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Detecting limits without switches
Many printers plotters do not use limit switches. Instead, they move the print head slowly towards the end stop until the motor stalls, and then back off from that point a certain distance and that's the home position or soft limit. What, roughly, do I need to do with EMC to get this behavior? Neil -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Detecting limits without switches
On Sunday 06 June 2010, Neil Baylis wrote: Many printers plotters do not use limit switches. Instead, they move the print head slowly towards the end stop until the motor stalls, and then back off from that point a certain distance and that's the home position or soft limit. What, roughly, do I need to do with EMC to get this behavior? That generally does work well at all. The reason is that when it jams, it jams at the steppers max torque, and it takes a random number of steps in the other direction, and even some hand help at times, to break it loose again. Neil -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) Old soldiers never die. Young ones do. -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Detecting limits without switches
I'm using servos, not steppers. I have real position feedback. Neil On Sun, Jun 6, 2010 at 9:28 AM, Gene Heskett gene.hesk...@gmail.com wrote: On Sunday 06 June 2010, Neil Baylis wrote: Many printers plotters do not use limit switches. Instead, they move the print head slowly towards the end stop until the motor stalls, and then back off from that point a certain distance and that's the home position or soft limit. What, roughly, do I need to do with EMC to get this behavior? That generally does work well at all. The reason is that when it jams, it jams at the steppers max torque, and it takes a random number of steps in the other direction, and even some hand help at times, to break it loose again. Neil -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) Old soldiers never die. Young ones do. -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- http://www.pixpopuli.com -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Detecting limits without switches
On Sunday 06 June 2010, Neil Baylis wrote: I'm using servos, not steppers. I have real position feedback. Neil Nevertheless, when in that search mode, I think I would try to see if the servo torque could be reduced to about 1/4 just for that mode. On Sun, Jun 6, 2010 at 9:28 AM, Gene Heskett gene.hesk...@gmail.com wrote: On Sunday 06 June 2010, Neil Baylis wrote: Many printers plotters do not use limit switches. Instead, they move the print head slowly towards the end stop until the motor stalls, and then back off from that point a certain distance and that's the home position or soft limit. What, roughly, do I need to do with EMC to get this behavior? That generally does work well at all. The reason is that when it jams, it jams at the steppers max torque, and it takes a random number of steps in the other direction, and even some hand help at times, to break it loose again. Neil --- --- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) Old soldiers never die. Young ones do. -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Cheers, Gene There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) Also, the Scots are said to have invented golf. Then they had to invent Scotch whiskey to take away the pain and frustration. -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Detecting limits without switches
I could maybe see monitoring following error... When the servo hit the limit - the error would increase. You could then use some logic that says when the following error reaches a certain amount - trip the 'virtual' limit switch. Maybe.. I could see lots of issues and as gene says - you would want to limit the output to the servos. If you have any I (in the pid) the pid loop will 'wind up' pretty quick sending the servos to maximum. Big picture it seems possible... :) (but I am just thinking out loud) sam On 6/6/2010 11:09 AM, Neil Baylis wrote: Many printers plotters do not use limit switches. Instead, they move the print head slowly towards the end stop until the motor stalls, and then back off from that point a certain distance and that's the home position or soft limit. What, roughly, do I need to do with EMC to get this behavior? Neil -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Axis on Debian Squeeze crashes
Hi,
I'm trying to get EMC2 and Axis running on Debian Squeeze, but I ran
into some serious difficulties. Axis crashes on initialization of a GL
widget. I tried this on an x86_64 machine (rtai mode) and on PowerPC
(simulation). Both crashes with an X error.
m...@maggie:~/develop/git/emc2/scripts$ ./emc
EMC2 - 2.5.0~pre
Machine configuration directory is '/home/mb/develop/git/emc2/configs/sim'
Machine configuration file is 'axis_mm.ini'
Starting EMC2...
X Error of failed request: BadWindow (invalid Window parameter)
Major opcode of failed request: 3 (X_GetWindowAttributes)
Resource id in failed request: 0x
Serial number of failed request: 691
Current serial number in output stream: 692
It crashes here:
lib/python/rs274/OpenGLTk.py:
24 class Togl(Widget):
...
36 def __init__(self, master=None, cnf={}, **kw):
37 _togl.install(master.tk)
38 Widget.__init__(self, master, 'togl', cnf, kw) #
This crashes
So I am wondering whether a fix or workaround could be done to get Axis
started.
I know that this might be a bug in a system library (tkinter, tcl, tk,
etc...), but anyhow a workaround would be appreciated (as installing a
different tcl/tkinter is a major pain). So I'm happy about anybody
telling me what could possibly go wrong here.
The crash happens with EMC 2.4 and 2.5-git.
--
Greetings Michael.
--
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GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the
lucky parental unit. See the prize list and enter to win:
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Re: [Emc-users] Detecting limits without switches
On Sunday 06 June 2010, Neil Baylis wrote: Just wanted to point out that there are millions of inkjet printers and plotters in operation right now that use this exact technique. And I would point out that those are 100% steppers, driving the carriage by toothed belts with solid plastic stops at the end of the carriage travel. They would have no problem backing away from such a stop as there is zero chance of binding the drive screw. Not to mention that those are generally mouse powered steppers, with only 1-2% of the power available that we use as a matter of fact. I only know of two printers in a history span of 50 years that actually had servos, and I own one of them, a xerox 1650-ro, the worlds fastest daisy wheel ever, and both the carriage return and the daisy wheel driver are servos. Stout ones too, it does 40cps so the daisy motor is pretty decent, and the carriage can do a full 18 return in about 80 milliseconds. It will make the table dance and eventually loosen every glue joint in it. Great printer, but I can't get its film ribbon cartridges anymore. The other was an IBM printer about the size of a 20' chest freezer. We had to place it over a wall, so the carriage moved in line with the wall, or it jiggled coffee cups out of the cabinets in the kitchen, 50 feet down the hall. Poorest quality dot matrix printer I ever saw. It's certainly practical. I think the reason they do it is to lower the cost. I imagine it also improves reliability by eliminating failure-prone parts (switches, connectors, etc). The reason I would do it is to lower the moving mass, as I'm attempting to build a very agile machine, and every ounce counts. If it's too complicated though, I'll rig up some optical sensor that can have low mass. On the other axis, I already have a reflective optical sensor that adds no moving mass and works well, but that's more difficult on this axis. Sam's point about the Integral term is important, and raises another question: is it possible to alter the PID tuning parameters after the .ini file has been read. I think the answer must be yes, because the calibration tool in the GUI does this, but not having read the code yet, I don't know how that works. But even assuming that's possible, I don't have a clear idea of where I would need to hook into EMC to do what I want. Neil On Sun, Jun 6, 2010 at 1:25 PM, Viesturs Lācis viesturs.la...@gmail.comwrote: Can You explain the reason, why would You want to do it this way? I think that such approach is breaking machine, it creates unnecesary loads and stresses to the construction of machine and simple switches are cheap and wiring them is easy. I think that it is trying to reinvent the wheel in some painful way. No offense, just my personal opinion :)) Viesturs 2010/6/6 sam sokolik sa...@empirescreen.com: I could maybe see monitoring following error... When the servo hit the limit - the error would increase. You could then use some logic that says when the following error reaches a certain amount - trip the 'virtual' limit switch. Maybe.. I could see lots of issues and as gene says - you would want to limit the output to the servos. If you have any I (in the pid) the pid loop will 'wind up' pretty quick sending the servos to maximum. Big picture it seems possible... :) (but I am just thinking out loud) sam On 6/6/2010 11:09 AM, Neil Baylis wrote: Many printers plotters do not use limit switches. Instead, they move the print head slowly towards the end stop until the motor stalls, and then back off from that point a certain distance and that's the home position or soft limit. What, roughly, do I need to do with EMC to get this behavior? Neil -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo
Re: [Emc-users] Detecting limits without switches
On Sun, 6 Jun 2010, Gene Heskett wrote: Date: Sun, 6 Jun 2010 21:18:52 -0400 From: Gene Heskett gene.hesk...@gmail.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Detecting limits without switches On Sunday 06 June 2010, Neil Baylis wrote: Just wanted to point out that there are millions of inkjet printers and plotters in operation right now that use this exact technique. -And I would point out that those are 100% steppers, driving the carriage by -toothed belts with solid plastic stops at the end of the carriage travel. -They would have no problem backing away from such a stop as there is zero -chance of binding the drive screw. Not to mention that those are generally -mouse powered steppers, with only 1-2% of the power available that we use as -a matter of fact. Umm, not any more, all the inkjets I've seen are really cheap servo systems (battery toy type motors and a linear mylar strip encoder) I think homing against a stop is OK with a torque controlled system (move slow and limit torque when homing) If your encoder has an index then this would give an accurate home. Of course without limit switches, theres nothing to stop such a system from slamming into the stop at full torque with drive or software error.. Peter Wallace -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Detecting limits without switches
On Sun, Jun 6, 2010 at 6:44 PM, Peter C. Wallace p...@mesanet.com wrote: Umm, not any more, all the inkjets I've seen are really cheap servo systems (battery toy type motors and a linear mylar strip encoder) Yes, they really cut the cost out of these things. The motors generally don't have ball bearings, just bushings. The worst kind of motor to use with continuous radial loads, but there ya go, that's what they use. One printer I recently gutted (Canon, I think) had no feedback at all. There was just a simple DC motor to drive the carriage. They were depending on the motor moving at constant speed with constant voltage, I guess. No limit switches, either. Perhaps they monitor motor current to know when it's at the limit. I think homing against a stop is OK with a torque controlled system (move slow and limit torque when homing) If your encoder has an index then this would give an accurate home. Actually, I hadn't thought of that. My encoder does have an index, but I don't have torque control. The drive does have a current limit, so maybe I could use that. Of course without limit switches, theres nothing to stop such a system from slamming into the stop at full torque with drive or software error.. Yes. I was planning to not have drive or software errors ;-) -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Detecting limits without switches
I was the coder for a version of printer based on the Canon A1210 and later the PJ1080 they were very early ink jets from the mid 1980's, they had servo drive and optical strip and we drove them as fast as possible but were limited by the possibility of burning out the motor. The optical strip had had two images the one for the servo loop(regular bars) and the other for home at each end. Just had to look at my old code to remind myself. Bugs did have the unfortunate bang when ther head hit the end stop the anti copy code I put in messed with the timing and a large bang was the result, it kept the ripoff merchants at bay. Dave Caroline On Mon, Jun 7, 2010 at 3:10 AM, Neil Baylis neil.bay...@gmail.com wrote: On Sun, Jun 6, 2010 at 6:44 PM, Peter C. Wallace p...@mesanet.com wrote: Umm, not any more, all the inkjets I've seen are really cheap servo systems (battery toy type motors and a linear mylar strip encoder) Yes, they really cut the cost out of these things. The motors generally don't have ball bearings, just bushings. The worst kind of motor to use with continuous radial loads, but there ya go, that's what they use. One printer I recently gutted (Canon, I think) had no feedback at all. There was just a simple DC motor to drive the carriage. They were depending on the motor moving at constant speed with constant voltage, I guess. No limit switches, either. Perhaps they monitor motor current to know when it's at the limit. I think homing against a stop is OK with a torque controlled system (move slow and limit torque when homing) If your encoder has an index then this would give an accurate home. Actually, I hadn't thought of that. My encoder does have an index, but I don't have torque control. The drive does have a current limit, so maybe I could use that. Of course without limit switches, theres nothing to stop such a system from slamming into the stop at full torque with drive or software error.. Yes. I was planning to not have drive or software errors ;-) -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Detecting limits without switches
Dave, do they use the optical strip transitions to time the firing of the ink droplets, or is it only used to control the print head? On Sun, Jun 6, 2010 at 7:55 PM, Dave Caroline dave.thearchiv...@gmail.comwrote: I was the coder for a version of printer based on the Canon A1210 and later the PJ1080 they were very early ink jets from the mid 1980's, they had servo drive and optical strip and we drove them as fast as possible but were limited by the possibility of burning out the motor. The optical strip had had two images the one for the servo loop(regular bars) and the other for home at each end. Just had to look at my old code to remind myself. Bugs did have the unfortunate bang when ther head hit the end stop the anti copy code I put in messed with the timing and a large bang was the result, it kept the ripoff merchants at bay. Dave Caroline On Mon, Jun 7, 2010 at 3:10 AM, Neil Baylis neil.bay...@gmail.com wrote: On Sun, Jun 6, 2010 at 6:44 PM, Peter C. Wallace p...@mesanet.com wrote: Umm, not any more, all the inkjets I've seen are really cheap servo systems (battery toy type motors and a linear mylar strip encoder) Yes, they really cut the cost out of these things. The motors generally don't have ball bearings, just bushings. The worst kind of motor to use with continuous radial loads, but there ya go, that's what they use. One printer I recently gutted (Canon, I think) had no feedback at all. There was just a simple DC motor to drive the carriage. They were depending on the motor moving at constant speed with constant voltage, I guess. No limit switches, either. Perhaps they monitor motor current to know when it's at the limit. I think homing against a stop is OK with a torque controlled system (move slow and limit torque when homing) If your encoder has an index then this would give an accurate home. Actually, I hadn't thought of that. My encoder does have an index, but I don't have torque control. The drive does have a current limit, so maybe I could use that. Of course without limit switches, theres nothing to stop such a system from slamming into the stop at full torque with drive or software error.. Yes. I was planning to not have drive or software errors ;-) -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- http://www.pixpopuli.com -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Detecting limits without switches
Neil Baylis wrote: Well, I just figured out how to add an optical sensor without adding any moving mass. This is the Y axis I'm working on, which is carried by the X axis. If I home the X first, then I can use a fixed optical sensor to home the Y axis. It would not be possible to home Y unless X was already at its home position. I think that should be OK. Ah HA! Thinking outside the box, VERY good! Jon -- ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
