This is corner lock and has nothing to do with the correction velocity of the Z axis.
JT On 7/8/2014 2:19 AM, Marius Liebenberg wrote: > Yes I will try. Even though the F word asked for say 3500mm/min, the > planner will slow the feed rate down when it comes to the end of a > segment. If the next segment is at an acute angle to the current one > then the velocity will slow down towards the corner. Once the corner is > turned, the velocity will accelerate again to match the F word. During > this slow down period the torch voltage will change due to the fact that > more metal is blown away and it then seems like the torch is to high. > The THC will bring the torch down and crash it into the job. > So its not the F word that changes but the way the planner accelerates > and decelerate the system as it moves with every Gcode request. > > If you have a very light weight gantry on a plasma you can set the > acceleration parameter very high and this problem becomes less > noticeable. But for bigger machines this is a real problem. If you look > at the latest work Les Newell (Sheetcam) has done on the plasma post > processors to enable users to include programmable codes that will stop > THC at a distance before a corner and resume at a distance after the > corner again, you will get an idea of how much of an issue this is. > > > > On 2014-07-07 22:09, John Thornton wrote: >> I don't understand how you are accelerating during correction from the >> requested velocity (the F word) which doesn't change during a cut? Can >> you break it down for a simple mind to understand? >> >> JT >> >> On 7/7/2014 12:48 PM, Marius Liebenberg wrote: >>> On 2014-07-07 14:09, John Thornton wrote: >>>> To avoid the divide by zero error I changed the original line in thc and >>>> thcud to: >>>> >>>> float min_velocity = requested_vel - (requested_vel * (velocity_tol * >>>> 0.01)); >>>> >>>> requested_vel = 100 >>>> velocity_tol = 10 >>>> min_velocity = 90 >>>> >>>> 90 = 100 - (100 * (10 * 0.01)) >>>> >>>> I'm not that great with math... when I did some examples of your >>>> simplified line it didn't work out for me. >>>> min_velocity = requested_vel * velocity_tol / 100 >>>> ? = 100 * 10 / 100 >>>> ? = 1000 / 100 >>>> 10 = 10 >>>> >>>> As for the suggestion to use requested_vel as part of the calculation of >>>> correction_vel I don't understand why that is good. IMHO the >>>> correction_vel should be as fast as the axis can correct without >>>> overshoot no matter what speed your cutting at. >>> JT we cannot make a correction to the Z axis at max requested velocity >>> purely because the motor will slip. So we have to introduce a gradual >>> accelerated correction. The setting for the min_velocity is related to >>> something else. The min velocity as a percentage of the requested >>> velocity is used to stop THC function when the torch velocity gets below >>> a certain percentage of the request3ed velocity. The reason for this is >>> to stop the torch from diving when the system applies constant velocity >>> rules to corners. I.E. the system slows down to take the corner and we >>> have to stop the THC during this time or else it will dive the torch >>> into the job. >>> >>> In summary, two things are very important. One, the correction must be >>> done with acceleration and, two, the minimum velocity rule to override >>> the THC must apply. >>> >>>> Any suggestions on making the description easier to understand are welcome. >>>> >>>> JT >>>> >>>> On 7/7/2014 2:09 AM, Marius Alksnys wrote: >>>>> I noticed this thread only now. This is my comment to this ticket: >>>>> https://sourceforge.net/p/emc/bugs/348/#9b18 >>>>> >>>>> On 06/27/2014 02:09 PM, Marius Liebenberg wrote: >>>>>> Hi Sebastian >>>>>> I am busy helping someone with a plasma setup and found that the changes >>>>>> that was made prior to the release of 2.6 does not reflect in master. So >>>>>> I would expect that it is not in 2.6 either. >>>>>> I am referring to a change that I made to the THCUD component. Someone >>>>>> else logged the issue but I fixed it and submitted fixed code on the >>>>>> issue tracker. >>>>>> >>>>> ------------------------------------------------------------------------------ >>>>> Open source business process management suite built on Java and Eclipse >>>>> Turn processes into business applications with Bonita BPM Community >>>>> Edition >>>>> Quickly connect people, data, and systems into organized workflows >>>>> Winner of BOSSIE, CODIE, OW2 and Gartner awards >>>>> http://p.sf.net/sfu/Bonitasoft >>>>> _______________________________________________ >>>>> Emc-developers mailing list >>>>> [email protected] >>>>> https://lists.sourceforge.net/lists/listinfo/emc-developers >>>> ------------------------------------------------------------------------------ >>>> Open source business process management suite built on Java and Eclipse >>>> Turn processes into business applications with Bonita BPM Community Edition >>>> Quickly connect people, data, and systems into organized workflows >>>> Winner of BOSSIE, CODIE, OW2 and Gartner awards >>>> http://p.sf.net/sfu/Bonitasoft >>>> _______________________________________________ >>>> Emc-developers mailing list >>>> [email protected] >>>> https://lists.sourceforge.net/lists/listinfo/emc-developers >>>> >> ------------------------------------------------------------------------------ >> Open source business process management suite built on Java and Eclipse >> Turn processes into business applications with Bonita BPM Community Edition >> Quickly connect people, data, and systems into organized workflows >> Winner of BOSSIE, CODIE, OW2 and Gartner awards >> http://p.sf.net/sfu/Bonitasoft >> _______________________________________________ >> Emc-developers mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-developers >> ------------------------------------------------------------------------------ Open source business process management suite built on Java and Eclipse Turn processes into business applications with Bonita BPM Community Edition Quickly connect people, data, and systems into organized workflows Winner of BOSSIE, CODIE, OW2 and Gartner awards http://p.sf.net/sfu/Bonitasoft _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
