On Wednesday, March 02, 2011 10:13:47 pm Jon Elson did opine: > Igor Chudov wrote: > > I do think that the motor is underpowered for the axis, if I had to > > move the axis continuously. However, if I only need to use it > > occasionally to adjust for tool height changes, it is OK. > > Right, I understand what you WANT to do, and it does make some sense, > but EMC is not designed to operate an axis in this manner. You want to > completely break the normal way of doing things. > > > What is the issue that you are pointing out, is that when the axis is > > "at rest", it is not really at rest from EMC2's standpoint, and its > > pid just keeps applying the same logic as during the moves. > > Yes, exactly, that is the normal design for an axis. > > > So, if I can find some way around that, I will be golden. > > I really think it is a bad idea, as the position will be uncontrolled > when not moving. > > > The better news is that based on limited post-change testing that I > > did (I was very tired by then at midnight), these changed in P and I, > > do work better as far as bringing the ppmc.0.DAC.03.value down after > > a while. > > > > The motor does succeed at getting f-error very low (think 0.00007), > > and the output of the motor controller becomes several times lower > > than in the past. It settles down kind of slowly, over several > > seconds. > > That is the I term working as it should, it keeps creeping until it > finally nulls out the error. Well, the real question is does the motor > still overheat? If not, you are done. Maybe strap a safety thermostat > to the motor to cause an estop if some time in the future it does run > hot again. > > > I know that my drive is in torque mode (controls current), and the > > current is about 10 times ppmc.0.DAC.03.value, per ammeter. So I can > > watch ppmc.0.DAC.03.value and I will know what the current is. I am > > pretty sure that the motor will not overheat from, say, 1 amp. > > No, even a small motor should be OK. Assuming a rotten motor with 1 Ohm > resistance, that will only dissipate one Watt with a 1 Amp idling > current. Those crummy Ametek motors with 4 Ohm resistance would > dissipate 16 W, which might still be in the safe area, but would get > pretty warm. > > Jon
Oh my, Jon. Anyway I run that through this aged wet ram, I still get 4 watts for that 1 amp & 4 ohms. I squared, where I=1, 1*1 is still 1, times 4 ohms=4 watts. 2 amps should be 16 watts. Or is my wet ram going away? I hope not. ;-D -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) <http://tinyurl.com/ddg5bz> What PROGRAM are they watching? ------------------------------------------------------------------------------ Free Software Download: Index, Search & Analyze Logs and other IT data in Real-Time with Splunk. Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
