Hey Hansjakob, I have some experience with exactly what you are dealing with, I built my own plasma table 6.5m x 2.5m with dual stepper motors on the gantry.
The dallur-thc sample config in version 2.1 is for just such a config but I have not included gantry kinematics (homing) yet, I hope to do so some time in February and I will update the dallur-thc sample config when I am done. For more info on the subject see: http://sourceforge.net/tracker/index.php?func=detail&aid=1075625&group_id=6744&atid=356744 http://www.linuxcnc.org/irc/irc.freenode.net:6667/emc/2006-11-09.txt http://www.linuxcnc.org/irc/irc.freenode.net:6667/emc/2006-11-17.txt http://dallur.com/index.php?id=130 Yours Jarl Stefansson (Dallur/Rugludallur) [EMAIL PROTECTED] On Mon, 2007-01-22 at 06:30 +0100, Hansjakob Rusterholz wrote: > Hi > > The system builder also tried the way with an shaft. > He said you will never get the desired accuracy and dynamics, but for > an plasma cutter, this may be not the problem. > The gantry was about one metric ton and accelerated in 300 ms to 30 m/ > minutes! > Only the servo amplifiers costed me over 2500 $ each (about 15 Years > ago) > > Hansjakob > > Am 22.01.2007 um 05:38 schrieb Kasparov, Aram: > > > Hi > > > > I am building similar plasma burning table (10 by 10 feet) and I > > am going to solve problem of second servo mechanically by putting > > long 10 feet shaft. That is more reliable and simple way to solve > > problem of wide gantry machine. The most important that way will > > reduce need in one servomotor and one amplifier and that in my case > > equal $950.0 + $550.0 > > > > > > > > Thank you, > > > > Aram Kasparov > > Hi Marc > > > > I was working long time on an six axis gantry laser system with about > > 2.7 to 1.8 meters travelling range. > > As I understood from the machine builder, they used also two > > "independent" servos fore both gantry sides, one was the master > > servo, and the other was tracking to the master. Both axis had linear > > encoders, home and end switches. > > For reference, the moved parallel to the home position and the linear > > encoder was used to adjust the home position final, because the have > > also some repetitive pattern (Ca all 10 mm) to get home position to > > about 1/1000 mm precise. If the home position was not found for both > > axis in some window, an emergency shutdown occurred. > > If you had bad luck, You had to loosening both gantry sides, and pre- > > adjust the gantry manually (even the technician moved once the servos > > controlled in opposite direction to get the machine working again > > after an bad crash.) > > > > I can not tell wich is the best solution for EMC2, but maybe you get > > some hints from my descriptions. > > > > Hansjakob > > > > Am 21.01.2007 um 00:08 schrieb Marc Bodmer: > > > >> Hello > >> I am on my way on building a gantry table for a plasma cutter and > >> setting up EMC. So far i am very impressed with EMC, thanks for > >> that great work. > >> > >> I am thinking about adding a second servo motor to the X Axis so > >> that it would be driven on both supported sides of the gantry. > >> However I am not so sure about how I could best do that. > >> > >> First I would like to explain my setup so you can imagine the > >> situation. The servos have planetary gearheads and drive the > >> gantry supports by timing belts. There are no linear encoders on > >> this axis, but the servos give resolver feedback to the servodrives > >> (Baldor Microflex). The drives convert the feedback to encoder > >> signals wich are fed to a Motenc Lite Card and EMC. > >> > >> 1. The first idea is to create a fourth servo PID position loop > >> for the new X1 axis and connect it to Xpos-cmd together with > >> axis X0. In the ini file I wouldn't add another axis, but > >> take the values for X1 and X0 from the X axis parameters. > >> For the feedback to the motion controller I would only attach > >> the X0 PID position feedback Xpos-fb. X1 Feedback wouldn't be > >> connected. > >> The problem I see in this setup is that first the feedback > >> of X1 isn't connected and I see no way for homing X1. > >> > >> 2. The second way would be to use the gantrykins component. > >> I had a look at the code, but did not see right away whether > >> there is a solution for the homing problem. The synchronisation > >> of these 2 axis however seems to be handled. > >> Did anybody use this module already? Any experiences? > >> > >> 3. Another way I would see is similar to the first way, except > >> that there wouldn't be a position loop for X1 axis. I have a > >> master-slave setup in mind where the master axis would be X0 > >> and the slave axis X1. The controller loop would control > >> position difference between these axis. Similar to the > >> HAL component "encoder_ratio". However I see no way again > >> in homing the slave axis. > >> > >> The homing problem is the following: Since there is always > >> a small position error between those 2 axis it would accumulate > >> up everytime X0 is homed, if X1 is dumbly homed at the same time. > >> There should be a way in first home X0 (of course both axis have > >> to move together) then X1 and instead of zeroing X1 it should > >> correct it's position in respect to X0. This way the error > >> would be eliminated in every homing cycle and not accumulate > >> up. I don't know if there are any "professional" ways of > >> solving this. (Would be interested in it if anybody knows about). > >> > >> Did anybody do such a gantry setup with a second servomotor > >> already? Any experiences? How to best do it? > >> I am pretty unsure where I should start. > >> > >> Thanks for any replies in advance > >> > >> regards > >> Marc > >> > >> > >> > >> > >> > >> > >> --------------------------------------------------------------------- > >> - > >> --- > >> Take Surveys. Earn Cash. Influence the Future of IT > >> Join SourceForge.net's Techsay panel and you'll get the chance to > >> share your > >> opinions on IT & business topics through brief surveys - and earn > >> cash > >> http://www.techsay.com/default.php? > >> page=join.php&p=sourceforge&CID=DEVDEV > >> _______________________________________________ > >> Emc-users mailing list > >> Emc-users@lists.sourceforge.net > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > ---------------------------------------------------------------------- > > --- > > Take Surveys. Earn Cash. Influence the Future of IT > > Join SourceForge.net's Techsay panel and you'll get the chance to > > share your > > opinions on IT & business topics through brief surveys - and earn cash > > http://www.techsay.com/default.php? > > page=join.php&p=sourceforge&CID=DEVDEV > > _______________________________________________ > > Emc-users mailing list > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > <winmail.dat> > > ---------------------------------------------------------------------- > > --- > > Take Surveys. Earn Cash. 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