Re: [Emc-users] HNC Lathe Tuning
On Thu, 2007-10-11 at 20:53 -0500, Jon Elson wrote: Kirk Wallace wrote: What is the status of PID_MAX_VEL and PWM_OUTPUT_SCALE? My understanding is that they were created to fix persistence issues. I am using EMC 2.1.7 so should I still use them? Arrghhh! I don't actually know. PID_MAX_VEL is a standard part of the modern ini file, and should still be used. It is to allow the servo algorithm to have a little extra headroom for acceleration. So PID_MAX_VEL is not unique to the UPC? PWM_OUTPUT_SCALE is an anachronism, as you say above. The best way to find out if it is still active is to do the following, after doing a cd to the configs directory you are using: grep PWM_OUTPUT_SCALE *.hal This will scan all the hal files for use of this parameter. If it doesn't show up at all, then it is not being used. Ahh, I have done it for you : # set output scaling from ini file # note that these are using PWM_OUTPUT_SCALE - they should # use OUTPUT_SCALE, but right now EMC2 re-writes that to # 1 on shutdown for some reason. Once that is fixed, this # should be changed setp ppmc.0.pwm.00.scale [AXIS_0]PWM_OUTPUT_SCALE setp ppmc.0.pwm.01.scale [AXIS_1]PWM_OUTPUT_SCALE setp ppmc.0.pwm.02.scale [AXIS_2]PWM_OUTPUT_SCALE You can just change these lines in hnc_motion-3a.hal and remove the PWM_ from the 3 lines above. Then, remove the now redundant lines with PWM_OUTPUT_SCALE from your ini file. For some reason that I can't recall, the above did not work for me right away, so I put PWM_OUTPUT_SCALE back the way it was, set it to -1, zeroed out the pid/ff settings and started over. Now I have P set to ~50 and FF1 set to .25 and everything else set to 0. My FERROR is now .0050 and MIN_FERROR is .0013. Typically, I am getting .0005 difference between the commanded position and the actual position, which is better than a couple of days ago, but I am hoping to do better. I just need to put in more effort. But, then, I think you will find that if you turn OUTPUT_SCALE back down to -1, you will get MORE voltage out of the servo amp. OUTPUT_SCALE (which is just an ini parameter for the hal parameter ppmc.0.pwm.xx.scale is a DIVIDER, not a multiplier ... snip There's really no reason to mess with output scale, other than making the sign correct to close the loop, as P does the same thing (although it IS a multiplier). Jon -- Kirk Wallace (Hardinge HNC lathe, California, USA http://www.wallacecompany.com/machine_shop/ ) - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] HNC Lathe Tuning
Kirk, Just to add a data point on my minimill system, it has 128000 encoder counts per inch. I can get the following error down to about 200 uInch peak, up to 50 IPM or more. But, it takes some effort to tune it to that level. On my Bridgeport, I have 2 counts per inch on X and Y, and I usually get down to .0005 following error on that machine. At standstill, the error is usually +/- .0001 or less. Jon - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] HNC Lathe Tuning
Kirk Wallace wrote: On Thu, 2007-10-11 at 20:53 -0500, Jon Elson wrote: Kirk Wallace wrote: What is the status of PID_MAX_VEL and PWM_OUTPUT_SCALE? My understanding is that they were created to fix persistence issues. I am using EMC 2.1.7 so should I still use them? Arrghhh! I don't actually know. PID_MAX_VEL is a standard part of the modern ini file, and should still be used. It is to allow the servo algorithm to have a little extra headroom for acceleration. So PID_MAX_VEL is not unique to the UPC? No, any version that uses the servo mode of operation will have it. Only setups that use stepgen don't use PID, I think. You can just change these lines in hnc_motion-3a.hal and remove the PWM_ from the 3 lines above. Then, remove the now redundant lines with PWM_OUTPUT_SCALE from your ini file. For some reason that I can't recall, the above did not work for me right away, so I put PWM_OUTPUT_SCALE back the way it was, set it to -1, zeroed out the pid/ff settings and started over. Now I have P set to ~50 and FF1 set to .25 and everything else set to 0. My FERROR is now .0050 and MIN_FERROR is .0013. Typically, I am getting .0005 difference between the commanded position and the actual position, which is better than a couple of days ago, but I am hoping to do better. I just need to put in more effort. Hmm, I don't know why that didn't work. (I see I still have it this way on my downloadable configs directories on my web page, too!) But, I have definitely done it on my development systems. Anyway, to get the error down, you want to have the P gain as high as possible. You need to add a small amount of D to keep it stable as you raise P. You might have P set somewhere between 80 and 250, depending on all the other factors (motor, supply voltage, friction, etc.) As the encoder resolution rises, then the linear dimension of each encoder count is smaller. So, with a high res encoder, the P term and all others needs to be larger. Jon - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Backlash compensation on EMC 4.16?
I was wondering how to use this functionality. When I select Settings | Set Backlash, I get a baffling EMC Calibration dialog that asks for: Axis: 0 P Gain: 100.0 I Gain: 0.0 D Gain: 0.0 Pos FF Gain: 0.0 Vel FF Gain: 0.0 Acc FF Gain: 0.0 Backlash: 0.0 Bias: 0.0 Max Cum Error: 0.0 Deadband: 0.001 Of these, the only settings I understand are Axis and Backlash. I hope the others aren't relevant to me, or at least the defaults are OK. The problem is, I don't see any way to set the per-axis backlash. I tried entering X, Y, Z, ... and various numbers for the axis, but no matter what I choose, the modifications I make are made to axis 0. How do I set backlash on a per-axis basis? - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Re C programming and tuneup/PID HELP. (Kirk Wallace)
Hello Aram, It's a great world we live in when we can communicate even though we don't agree on how many letters in the alphabet. :-) I don't think the problem is quite that simple. For example, your approach doesn't take tool length or diameter compenstation into account. I don't think we would like the machine operator on the shop floor to have to go back to a very expensive program like Catia to generate a new program just because he broke a tool. By the way. There are 18 letters in the (Hawaiian) alphabet. :-) Ken [EMAIL PROTECTED] Mark Kenny Products Company, LLC 55 Main Street Voice: (888)ISO-SEVO (888)476-7386 Newtown, CT 06470Fax: (203)426-9138 http://www.MarkKenny.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of [EMAIL PROTECTED] Sent: Thursday, October 11, 2007 7:57 PM To: emc-users@lists.sourceforge.net Subject: [Emc-users] Re C programming and tuneup/PID HELP. (Kirk Wallace) Hello Kirk. My job is NC programmer. We have all type of machines and all imaginable CNC controllers in addition to that our company buys every several weeks one new machine. With that variety of controllers I can see real issue with postprocessor. As more machine in shop the more needs in postprocessor that should accommodate different controllers. Here is something from me! Our shop use CAD/CAM Catia ( right now I am in week long Catia training class in Renton WA) and most other shop also using some kind CAD/CAM package. Less and less shops use hand writing programming but there are many who still does that. Problem as I can see in that CAD/CAMs have their own G cycles and controllers their own. When I make CAD/CAM software generate code without cycles (canned cycle G81-G86 ?) and go with point to point option of motion generation I have less problems with successful generation of post processor. Question: why just drop all G code except of basic one what can be universally used for all controllers? To basic code I can relate: 1. G01 2. G02 3. G03 4. G04 (Dwell) Sintecs X move in x direction Y motion in y direction. Z motion in z direction U incremental motion in x direction. V incremental motion in y direction. W incremental motion in z direction A rotation motion around X axes. B rotation motion around Y axes. C rotation motion around Z axis. akA incremental rotational motion around X ases. akBincremental rotational motion around Y ases. akC incremental rotational motion around Z ases. With use of CAD/CAM software and basic code mentioned above I can generate all program up to 100 miles long but benefit is that it is universally will be used by all controllers. It is point to point motion only. 100 miles long program is no problem for EMC2, am I right? It is the same as alphabet 28 letters only and one can compose everything! ( grammer free too in this case) So, I want to create only incremental rotational motion for axes A B and C. wich I call akA akB and akC ( or what ever) and make EMC2 able to accept simple codes for point to point motion that is 100 miles long. This is my vision for the next level of developments. Please let me know all your?s objections for that idea. Thank you, Aram Kasparov (ak) - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Stepper motors and Gecko's
I posted last week about steeper motors maybe week? So I thought I would follow up and ask some more questions. Anyway I was using terminal #7 on the gecko 210 tied to my estop to ground to disable the drive. This pulls the motor windings to zero, (gecko doc,s) I always wonder why the drives were noisy and so were the motors. as I ran the machine more and more, the motors would quit down and run graet with no missed steps after about 5 min. or so. I disconnected terminal #7 and the problem was fixed. Anyone with any ideas what demons were at work here? Thought I was being extra safe! over thought . Thanks Again Al - Catch up on fall's hot new shows on Yahoo! TV. Watch previews, get listings, and more!- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] HNC Lathe Tuning
Kirk Wallace wrote: I was also thinking that it would be good to have EMC loop an axis move and have halscope update on the trigger, as it already does, and then be able to tweak the PID settings as EMC loops. When I do PID tuning I usually skip EMC completely. I just set up a simple single axis HAL configuration using siggen as the signal source. Run the siggen square wave output through a limit3 block and you get a classic trapezoidal velocity profile of whatever length and repetition rate you want. Then I use setp commands from the halcmd command line to tune. Once I have values I like, show param pid displays them, I jot them down, and enter them into the ini file or wherever they are needed. Regards, John Kasunich - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Stepper motors and Gecko's
Alfred Smart wrote: I posted last week about steeper motors maybe week? So I thought I would follow up and ask some more questions. Anyway I was using terminal #7 on the gecko 210 tied to my estop to ground to disable the drive. This pulls the motor windings to zero, (gecko doc,s) I always wonder why the drives were noisy and so were the motors. as I ran the machine more and more, the motors would quit down and run graet with no missed steps after about 5 min. or so. I disconnected terminal #7 and the problem was fixed. Anyone with any ideas what demons were at work here? Yes. You need a multi-pole relay, so you can use one pole for each Gecko drive. There are large current pulses flowing through the motor supply ground terminal as the drive switches each winding on and off. Due to the resistance and inductance of the wires connecting all these motor supply grounds together, they are not really held at the same voltage. You'd be amazed at the voltage that can be induced in a short length of heavy wire by these fast-rise current pulses, even 20 V or more can be seen. If you have even 6 V difference between two of the Gecko drives, then one drive can be enabled while another is disabled. So, you need to have no common connection between the drives, other than the motor supply wires. If your estop circuit de-energizes the relay coil when in Estop mode, then use a normally-closed contact for each Gecko. When the relay drops out, it shorts pin 7 to 12 on the same drive only. Use a 4PDT relay for up to 4 axes. If you want to know why things quieted down after 5 minutes, it may be the FETs warmed up and their conductivity decreased. Jon - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] HNC Lathe Tuning
On Fri, 2007-10-12 at 20:37 -0500, Jon Elson wrote: ... snip So at 5k cpi on my lathe, I should be able to get similar results, I hope. Thanks Jon. Well, 5000 is a lot less than 128,000, and 4 times coarser than my 20,000 counts/inch. So, it would be normal to expect the best following error you could achieve may be worse. One encoder count is .0002 so you will never get better than that. Jon Opps. It's really 50k cpi. I'm going to have to get a dog so I can blame my mistakes on it. I have a plot for X here: http://www.wallacecompany.com/cnc_lathe/HNC/emc2/p95i4d3ff1_1.png I started working on Z and totally missed it up. Hopefully, I'll be able to fix it tomorrow. -- Kirk Wallace (Hardinge HNC lathe, California, USA http://www.wallacecompany.com/machine_shop/ ) - This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now http://get.splunk.com/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
