On Sun, 25 Dec 2011, gene heskett wrote:
On Sunday, December 25, 2011 10:11:27 AM [email protected] did opine:On Sat, 24 Dec 2011, gene heskett wrote:On Saturday, December 24, 2011 03:43:00 PM [email protected] didopine:On Sat, 24 Dec 2011, gene heskett wrote:On Saturday, December 24, 2011 02:26:16 PM [email protected] didopine:On Sat, 24 Dec 2011, gene heskett wrote:On Saturday, December 24, 2011 01:48:17 PM [email protected] didopine:Probotix equipment 40VDC 10Amp Linear Power Supply PBX-RF RF Isolated CNC Breakout Board 3 - Uni-polar Stepper Motor Chopper DriversSpecs on this driver board please?http://www.probotix.com/manuals/ProboStepVX.pdf3 - 280 OzIn 8-Wire Stepper Motor I have run this setup for over a year with no problems, so I thought I would create one I have a used Pacific Scientific Powermax II stepper model P21NRXA-LNF-NS-00 I could not send the datasheet for the motor so I sent the link to it http://www.electromate.com/db_support/downloads/Nema23PowermaxII. pd fThis data sheet shows 2 things, one that it does run hot, very hot. 130C in a 40C environment. To me that is too hot, but they know their varnish better than I do. Any other comments I'll wait for the driver specs to make.I added a 4th Uni-polar Stepper Motor Chopper Drivers Wired motor and driver and they actually work Issue 1 The motor gets VERY hot I have run the other motors for a couple of hours and they got hot but the SI motor will burn your fingers after about 15 minutes The manual for the Uni-polar Stepper Motor Chopper Drivers says to set the current limiter to .145 * target_current, 2.8 amps = .406 I reduced it to .38 and it still gets too hot Issue 2 The motor is slow The label says max 1500 rpm but I can only get a fraction of that I use EMC 2.4.6 The driver is set to 1/8 stepping [AXIS_3] TYPE = ANGULAR HOME = 0.0 MAX_VELOCITY = 360 MAX_ACCELERATION = 5000.0 STEPGEN_MAXACCEL = 6250.0 SCALE = 4.44444444444 FERROR = 1 MIN_FERROR = .25 MIN_LIMIT = -9999.0 MAX_LIMIT = 9999.0 HOME_OFFSET = 0.0Off topic, from this I assume its running a rotary table?Probably but now it is just a motor sitting on the benchIf that table has the usual 72 or 90 gear down, those settings are a bit off.If I do gear this thing down I will fall asleep waiting for it to turnFrom one of my ini files that included a 425oz motor on a 4" Grizzlytable, direct drive to the worm: [AXIS_3] TYPE = ANGULAR HOME = 0.0 MAX_VELOCITY = 81.8965517241 MAX_ACCELERATION = 1200.0 STEPGEN_MAXACCEL = 1500.0 SCALE = 200.0 FERROR = 1 MIN_FERROR = .25 MIN_LIMIT = -9999.0 MAX_LIMIT = 9999.0 HOME_OFFSET = 0.0Your setting do get me more rpms but g0 a180 results in many revolutions In the not too distant future I hope to be driving a rotary table with this So how do I adjust these setting for whatever my final reduction will beThat scale is telling emc how many steps it has to move the motor to make one units worth of motion. For a table I think its 1 degree but I can be corrected since it could be a radian too. What I meant by the geardown, is how many turns of the dial handle shaft on the table does it take to make one full 360 degree turn, and depending on the table it could be 90 or 72 full turns of the worm shaft to make one full turn of the table.I am still quite confused My ignorance is killing me [EMCMOT] EMCMOT = motmod COMM_TIMEOUT = 1.0 COMM_WAIT = 0.010 BASE_PERIOD = 28000 SERVO_PERIOD = 1000000 [TRAJ] AXES = 4 COORDINATES = X Y Z A MAX_ANGULAR_VELOCITY = 8035.71 DEFAULT_ANGULAR_VELOCITY = 60.00 LINEAR_UNITS = inch ANGULAR_UNITS = degree CYCLE_TIME = 0.010 DEFAULT_VELOCITY = 0.33 MAX_LINEAR_VELOCITY = 3.30 [AXIS_3] TYPE = ANGULAR HOME = 0.0 MAX_VELOCITY = 7633.92857143Laying on the table & measuring the shaft rotation, this wouldn't be very fast. a fraction over 21 rpm, nominally 3 seconds per rev. Not rps, rpm. But when 'scaled' to drive a table, its way faster than any stepper could be driven to at my usual psu voltage of 28 volts. A big Gecko running on 80 volts, maybe.
MAX_VELOCITY = 7633.92857143 (degrees per second), right????? (7633.92857143 / 360) * 60 = 1272.32142857166666666660 rpm Which is what I see whem I test with stepconf But locks up in Axis See attached
MAX_ACCELERATION = 50000.0 STEPGEN_MAXACCEL = 62500.0These 2 are, IMO, way too high.SCALE = 4.44444444444Is this the 'scale' that turns the motor 1 degree?
Yes???
From integrator manual
SCALE = 4000 ( HAL ) Specifies the number of pulses that corresponds to a move of one machine unit as set in the [TRAJ] section. For stepper systems, this is the number of step pulses issued per machine unit. For a linear axis one machine unit will be equal to the setting of LINEAR_UNITS. For an angular axis one unit is equal to the setting in ANGULAR_UNITS. With 1/8 stepping 4.444... pulses per degree
What happens when you multiply this value by the gear ratio of the table, probably 72 or 90. In any event my calculator says that corresponds to a microstep of 8, for a motion of 1 degree as set in the [TRAJ] section. Ostensibly correct, until you attach it to the table, at which point this value will need to be multiplied by the handle on the worm to table bull gear ratio, usually 72/1 or 90/1. This will speed up the motor by the same ratio because now its table speed, not motor speed.FERROR = 1 MIN_FERROR = .25 MIN_LIMIT = -9999.0 MAX_LIMIT = 9999.0 HOME_OFFSET = 0.0 These values are created by stepconf While in stepconf they work perfect If I tell it to rotate 180 degrees it rotates 180 degrees and it will jog at a very high speed But in Axis only slow speed works g0 a180 gets me "joint 3 folow error"This generally speaking should go away when MAX_ACCELERATION and STEPGEN_MAXACCEL are suitably reduced. Divide them by about 15 and work back up in increments of 10% or so until it can't keep up. I normally have the line in my .ini file set to allow a feedrate up to 150% of normal, and I set these two values so that I can do 1" if linear, and 15 to 30 degrees if angular, jogs without a following error, at the 150% feed rate. Your scale factor between them is suitable at 100/125% ratio, so I would maintain that general ratio. ISTR the wiki says only a 10% diff for stepgen catchup headroom but I have found 15 to 25% to be more usable here. YMMV. :) Bear in mind that extreme diffs here will tend to promote motor stalls when it cannot accelerate that fast however. It's better to cause the whole machine to slow a bit on a speed or direction change than to cause a stall, wrecking parts and or tooling. My own tables motor, a 425oz/in, running on 28 volts, will turn the motor perhaps 150 rpm at full speed. That IIRC turns the table at about 25-35 seconds for a full 360 degree turn of the table itself with my MAXVEL setting.Richard ------------------------------------------------------------------------ ------ Write once. Port to many. Get the SDK and tools to simplify cross-platform app development. Create new or port existing apps to sell to consumers worldwide. Explore the Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-usersCheers, 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) My web page: <http://coyoteden.dyndns-free.com:85/gene> You will wish you hadn't. ------------------------------------------------------------------------------ Write once. Port to many. Get the SDK and tools to simplify cross-platform app development. Create new or port existing apps to sell to consumers worldwide. Explore the Intel AppUpSM program developer opportunity. appdeveloper.intel.com/join http://p.sf.net/sfu/intel-appdev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
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