> 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.
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. 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. What faults, EMC gets a following error, or the Granite drive gets a fault? >> Another thing we think might be of issue is that we are using rack and >> pinion and that it isn't 100% linear either. Servos tend to like a >> consistent load and we think some areas of movement along the rack are >> easier, some are harder, just due to the inaccuracies of the rack and pinion >> and the design of the bearings/rails/assembly we are using. All of this is >> speculation at this point, just things we have discussed. We thought we >> had made progress on tuning the Granite drives but when we went to run EMC, >> the axis will fault fairly often even at very low accel and speeds and >> nearly always faults at one specific location (within a couple inches of a >> specific point). We have scrutinized that place and can see nothing >> different from another other place, but it just faults there quite often and >> when moving in one specific direction. It is baffling. We have been over >> the mechanicals and wiring separately and together (two of us having been >> working on this), and we are quite sure everything is mechanically sound and >> nothing is wired incorrectly or improperly. >> Oh, and of course, that symptom of faulting at one specific location could be due to a defective cable that gets erratic contact at that spot. Jon ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2d-oct _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
