aaron Moore wrote: > I think I would like to clear a few miss understandings here. I am > not an engineer and will never be one. I am a furniture maker/designer > with a keen interest in digital technologies and linux. I have built > a 1.5m x 1.5m gantry style router table with high spec rails, carriage > and bearings. It has been two years in the planning and taken 2-3 > months to build in my spare time. I bought a CNC Kit from an online > company in UK (who have not been able to sort my problem out) consisting > of 3 x MSD542 micro controllers, 3 X FL86STH High torque Nema 34 Stepper > motors and 2 X L6-PF11-001 (PS407) power supply units. The motors are > connected in parallel with micro stepping set to 16 and the power at 4.2 > amps. It has cost me well over £1000 and I would like to get it to work > with a reasonable amount of accuracy.
Now we're getting somewhere. Thanks for the information. > I have tried using many settings of speed and acceleration but I always > get a the same result. When engraving a line text the individual letters > look okay but they are always misplaced along the y axis by between 5mm > and 30mm, and always in the same direction. It sounds like you are losing position during rapid moves only. The move between letters is probably a G0 rapid, which goes as fast as EMC thinks the machine can go, while the moves within the letters are G1 lines or G2/G3 arcs, both at some specified feedrate. If you were having this problem only when speed and/or accel limits are set high, then I would think you were simply asking the motors for more than they could do. Since you have tried "many" settings (could you give us an idea of the lowest and highest you have tried?) that is less likely to be the problem. Specifically, if you set the limits _very_ low, and still have the problem, it probably isn't your limits. > My question today is could > this be because I have not used shielded cable to wire the powersupply > and drivers together. If this could be the problem what kind of cable > should I use. Or is there something else I should look into Nothing is impossible, but I think that is quite unlikely. As the first step toward troubleshooting this I would suggest "simplify, simplify, simplify". If the Y axis is the problem, run only the Y axis. Running a complex g-code program makes it harder to understand what is going on (engraving text is complex). So write a very simple program that simply moves the axis back and forth some moderate distance 100 times, while not cutting. Something like this: F100 (100mm/minute) G1 Y0 (starting point) M0 (pause - set a ruler under the tip of the tool) G1 Y50 (move 25mm = about 1 inch) G1 Y0 (back to start) G1 Y50 (repeat till bored) . . . G1 Y0 (back to start) When the program ends, is it parked at the same spot over the ruler, or has it moved? If it works using F100, increase the feed rate and see what happens. If not, lower the feed rate. If it works for a variety of F words, then change the G1 to G0 (rapid). Let us know the results. A test like this lets you focus on one thing at a time. As John Thronton has mentioned - if you are losing steps for any reason, everything else will be wrong. You said a few messages back that it works with Mach. What kind of speed are you getting with Mach? 100mm/min? 500? 1000? 5000? When using Mach, how long does it take to get to max speed? A couple of seconds? A noticeable fraction of a second? Or so fast you can barely hear it accelerate? That will give us an idea of what the mechanical limits of the machine are. If you are getting good results with Mach at a wide range of speeds, and bad results with EMC over the same wide range, it is unlikely that the problem is mechanical. Are you using the same PC for both Mach and EMC? Some parallel ports have marginal voltage levels - if the EMC PC has one of those, you could be losing pulses for that reason. If it is the same PC and same parallel port for both programs, you can pretty much rule that out. If it is indeed a timing thing (which seems likely so far), the next step would be to look at your configuration files. Can you post your .ini and .hal files at http://pastebin.ca/, and then post the URL here? Regards, John Kasunich ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
