On Oct 19, 2011, at 12:25 AM, Jon Elson wrote: >> On 10/18/2011 9:34 PM, Tom Easterday wrote: >> >>> >>> We think the motors are a good size for what we designed. They might be a >>> little too big if anything This might be part of the problem we are having >>> tuning it, that the truck is fairly light and motor fairly beefy. One turn >>> of the motor is pi/2 (1.57) inches of movement linearly. > So, for a motor rated at 3200 RPM, you have an ability to move at 3200 x > 1.57 = 5024 IPM. > What rapid traverse speed are you really trying to achieve? For a > router running at 300 IPM, > that would be a motor speed of 191 RPM. For 30 IPM, the motor would be > turning only > 19 RPM! This sounds to me like a serious mismatch, I agree with Dave. > '
We are mainly going to be using a plasma torch so may be cutting at 200-1000 ipm (will be based on material and I haven't researched actual rates - but should obviously). We would like rapids to be as fast as reasonable, and this was part of the reason for selecting servos at all and those motors specifically. With the current setup we will probably have rapids at 2500 ipm. > Continuous rated torque is 226 Oz-In, and it appears your pinion has a > pitch diameter > of 1/2", so that gives 56.5 Lbs of linear force to the rack, which > sounds OK to me. > But, if your gantry is heavy, that might reduce acceleration. The pulley on the motor is 20-tooth which connects via belt to a 40-tooth pinion gear with an attached 20-tooth gear riding the rack. One motor rev is PI / 2 inches in linear movement. The gantry is actually fairly light. It is two pieces of extruded aluminum held together with some aluminum cast parts from CastCNC (see attached pic). > > If the spot where it trips feels looser that other parts of the travel, > there may be too much > backlash in the rack at that spot that is destabilizing the servo loop. This spot turned out to be not a mechanical problem but an accumulating following error due to noise (and additional pulses) on our step lines. Thanks, -Tom ------------------------------------------------------------------------------ The demand for IT networking professionals continues to grow, and the demand for specialized networking skills is growing even more rapidly. Take a complimentary Learning@Ciosco Self-Assessment and learn about Cisco certifications, training, and career opportunities. http://p.sf.net/sfu/cisco-dev2dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
