When I built my stepper powered plasma cutter I did some basic tests to see if I was loosing steps. I mounted a dial indicator and jogged to a known point on the dial then did some G0 moves out and about then back to the known point. If I didn't return to the exact spot or as good as the backlash then I know I lost steps. If I returned to the exact spot then I knew I didn't loose any steps. I ran this test over and over increasing my speeds and acceleration until I found the breaking point. Then I backed way off... To compound things your process has side loads induced by the cutting bit that might overpower your steppers and cause you to loose steps. Things like dull cutters will increase the loads a lot. As a furniture maker you know how wood eats steel and carbide for lunch...
Have you done a basic test for lost steps without a load and then a test for lost steps with a load? If your loosing steps increase the step and direction to some number that you are certain will work like 20,000 ns. Decrease accl and speed to some real low number and repeat the tests. It will never be accurate if you are loosing steps. First you must find out if it is in the electronics or your mechanics. Please post some pictures of your machine on photobucket or similar. John On 21 May 2008 at 19:53, 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, carriages 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. > > 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. 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 > > If any one can offer some advise I would be very grateful > > Cheers > Aaron > > > > -- > Powered by Outblaze > > ---------------------------------------------------------------------- > --- 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 > ------------------------------------------------------------------------- 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
