## Re: [Emc-users] Emc.ini

 Re: [Emc-users] Emc.ini From: Ray Henry - 2003-10-29 18:39:14 ```Hi John What kind of stepper drive amp are you using and does it microstep? If it does, then you would multiply 20 tpi * 200 steps * microsteps per step * any belt or gear ratio to get the correct INPUT_SCALE and OUTPUT_SCALE. You also have the right idea when you say that you can tweak this number to match the real distance traveled. I recently found a 5 mm ballscrew that really needed 2031.12 for direct drive half step in order to get an inch of travel. Ray BTW 16000 is the number used by Sherline for their CNC setup which sounds very similar to what you have here. They use 1/4 step microstepping so 4000 * 4 is the correct answer. On Wednesday 29 October 2003 11:39 am, John Hofstad-Parkhill wrote: > I'm sure this has been visited about a zillion times. I cannot make any > sense out of several parameters for emc.ini and how to set them such > that I am even close to understanding why. > > 1ghz Pentium > Brain dead install - developers > > Hobby CNC 4-axis kit > Vexta PK266-01A-C23 steppers > 200 steps/revolution > Holding torque 125 oz/in > current/phase 1a > Voltage 7.4 > Resistance/phase 7.4 ohm/phase > Inductance/Phase 10 mH/phase > Rotor inertia 1.64 (something squared, not sure) > > Supply is rated 31vdc 1.25A /phase continuous > > The lead screws on my machine are 20tpi = .050" per revolution. > > I understand the .0393700... is the inch to metric conversion 1/25.4 > > for INPUT_SCALE, I have tried samples, and tried tweaking the settings. > Calculations for this value prove fruitless. For instance, if I follow > the examples, one states: > 200 steps/revolution, 1.5mm lead screw = 200 / 1.5 = 133.333333~ > > So, I think... > 200 steps/revolution 20 TPI lead = .050"/revolution = 200 / .050 = 4000 > > Using that value for input_scale and output_scale (the "tuning freqmod" > manual says to do this) > > The motors turn, but the readout is not even close. > > By quadrupling the values, input_scale = 16000 0, I can jog the x-axis > such that it is nearly correct. Except I can make no sense out of > 16000. I have very accurate measuring equipment, so once I get close, I > can tweak it - at least within tolerance. > > I am measuring distance travelled using a 2" dial indicator. I know I > can get more accurate later, but this gives me a good ballpark reading. > > I tried converting input scale to mm, using approximately > 157.48031496064 as a value for steps/mm. But when running emc from the > command line it complains about an incorrect value for INPUT_SCALE. > > I am clueless. I have read the white papers (stepper motor basics), but > that really does not tell me what I am trying to understand. And, > apparantly my setup(configuration) has not yet been tried. Most of the > fellows seem to be running metric, and well, I can't. > > I have no idea what the motors are supposed to sound like when they are > running correctly. If I change the input_scale = 1000 then the motors > keep running on a single jog. So clearly I am missing the relationship > between the different values p=???, deadband, acceleration, > max-velocity - says "an appropriate limit for this axis and your > motors" ... how would I know that? What are the units? Based on my > motor, how could I calculate this value? > > I'd rather stick with Linux over DeskNC for a zillion reasons, > including I'm not even sure I can find a DOS system around here. I have > a couple of Linux boxes on my network, which is primarly Windows 2000. > > Sorry about this, I'm obviously eager to get my first piece of G-code > to do something. > > TIA. ```

 [Emc-users] Emc.ini From: John Hofstad-Parkhill - 2003-10-29 17:38:56 Attachments: Message as HTML ```I'm sure this has been visited about a zillion times. I cannot make any = sense out of several parameters for emc.ini and how to set them such = that I am even close to understanding why. 1ghz Pentium Brain dead install - developers Hobby CNC 4-axis kit Vexta PK266-01A-C23 steppers 200 steps/revolution Holding torque 125 oz/in current/phase 1a Voltage 7.4 Resistance/phase 7.4 ohm/phase Inductance/Phase 10 mH/phase Rotor inertia 1.64 (something squared, not sure) Supply is rated 31vdc 1.25A /phase continuous The lead screws on my machine are 20tpi =3D .050" per revolution. I understand the .0393700... is the inch to metric conversion 1/25.4 for INPUT_SCALE, I have tried samples, and tried tweaking the settings. = Calculations for this value prove fruitless. For instance, if I follow the examples, one states: 200 steps/revolution, 1.5mm lead screw =3D 200 / 1.5 =3D 133.333333~ So, I think... 200 steps/revolution 20 TPI lead =3D .050"/revolution =3D 200 / .050 =3D = 4000 Using that value for input_scale and output_scale (the "tuning freqmod" = manual says to do this) The motors turn, but the readout is not even close. By quadrupling the values, input_scale =3D 16000 0, I can jog the x-axis = such that it is nearly correct. Except I can make no sense out of 16000. I have very accurate measuring equipment, so once I get close, I can = tweak it - at least within tolerance. I am measuring distance travelled using a 2" dial indicator. I know I = can get more accurate later, but this gives me a good ballpark reading. I tried converting input scale to mm, using approximately = 157.48031496064 as a value for steps/mm. But when running emc from the = command line it complains about an incorrect value for INPUT_SCALE.=20 I am clueless. I have read the white papers (stepper motor basics), but = that really does not tell me what I am trying to understand. And, = apparantly my setup(configuration) has not yet been tried. Most of the = fellows seem to be running metric, and well, I can't. I have no idea what the motors are supposed to sound like when they are = running correctly. If I change the input_scale =3D 1000 then the motors = keep running on a single jog. So clearly I am missing the relationship = between the different values p=3D???, deadband, acceleration, = max-velocity - says "an appropriate limit for this axis and your motors" = ... how would I know that? What are the units? Based on my motor, how = could I calculate this value? I'd rather stick with Linux over DeskNC for a zillion reasons, including = I'm not even sure I can find a DOS system around here. I have a couple = of Linux boxes on my network, which is primarly Windows 2000. Sorry about this, I'm obviously eager to get my first piece of G-code to = do something. TIA.```
 Re: [Emc-users] Emc.ini From: Ray Henry - 2003-10-29 18:39:14 ```Hi John What kind of stepper drive amp are you using and does it microstep? If it does, then you would multiply 20 tpi * 200 steps * microsteps per step * any belt or gear ratio to get the correct INPUT_SCALE and OUTPUT_SCALE. You also have the right idea when you say that you can tweak this number to match the real distance traveled. I recently found a 5 mm ballscrew that really needed 2031.12 for direct drive half step in order to get an inch of travel. Ray BTW 16000 is the number used by Sherline for their CNC setup which sounds very similar to what you have here. They use 1/4 step microstepping so 4000 * 4 is the correct answer. On Wednesday 29 October 2003 11:39 am, John Hofstad-Parkhill wrote: > I'm sure this has been visited about a zillion times. I cannot make any > sense out of several parameters for emc.ini and how to set them such > that I am even close to understanding why. > > 1ghz Pentium > Brain dead install - developers > > Hobby CNC 4-axis kit > Vexta PK266-01A-C23 steppers > 200 steps/revolution > Holding torque 125 oz/in > current/phase 1a > Voltage 7.4 > Resistance/phase 7.4 ohm/phase > Inductance/Phase 10 mH/phase > Rotor inertia 1.64 (something squared, not sure) > > Supply is rated 31vdc 1.25A /phase continuous > > The lead screws on my machine are 20tpi = .050" per revolution. > > I understand the .0393700... is the inch to metric conversion 1/25.4 > > for INPUT_SCALE, I have tried samples, and tried tweaking the settings. > Calculations for this value prove fruitless. For instance, if I follow > the examples, one states: > 200 steps/revolution, 1.5mm lead screw = 200 / 1.5 = 133.333333~ > > So, I think... > 200 steps/revolution 20 TPI lead = .050"/revolution = 200 / .050 = 4000 > > Using that value for input_scale and output_scale (the "tuning freqmod" > manual says to do this) > > The motors turn, but the readout is not even close. > > By quadrupling the values, input_scale = 16000 0, I can jog the x-axis > such that it is nearly correct. Except I can make no sense out of > 16000. I have very accurate measuring equipment, so once I get close, I > can tweak it - at least within tolerance. > > I am measuring distance travelled using a 2" dial indicator. I know I > can get more accurate later, but this gives me a good ballpark reading. > > I tried converting input scale to mm, using approximately > 157.48031496064 as a value for steps/mm. But when running emc from the > command line it complains about an incorrect value for INPUT_SCALE. > > I am clueless. I have read the white papers (stepper motor basics), but > that really does not tell me what I am trying to understand. And, > apparantly my setup(configuration) has not yet been tried. Most of the > fellows seem to be running metric, and well, I can't. > > I have no idea what the motors are supposed to sound like when they are > running correctly. If I change the input_scale = 1000 then the motors > keep running on a single jog. So clearly I am missing the relationship > between the different values p=???, deadband, acceleration, > max-velocity - says "an appropriate limit for this axis and your > motors" ... how would I know that? What are the units? Based on my > motor, how could I calculate this value? > > I'd rather stick with Linux over DeskNC for a zillion reasons, > including I'm not even sure I can find a DOS system around here. I have > a couple of Linux boxes on my network, which is primarly Windows 2000. > > Sorry about this, I'm obviously eager to get my first piece of G-code > to do something. > > TIA. ```
 Re: [Emc-users] Emc.ini From: Ray Henry - 2003-10-29 18:46:46 ```John I failed to answer one other question that you had. I'll snip your post to clarify. On Wednesday 29 October 2003 11:39 am, John Hofstad-Parkhill wrote: I'd rather stick with Linux over DeskNC for a zillion reasons, > including I'm not even sure I can find a DOS system around here. http://www.freedos.org may be the answer but I have not tried to run any of the dos based cnc programs with it. I hear that it is getting very good at adding in communication and a bit of graphical stuff as well. Ray ```