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I was wondering if possible i have my current set to low. I'm trying to isolate the cause for lost steps on my x travel. it does it at random, and its always a very small amount and in both directions. Always on a straight cut. When I up'ed the feedrate it went away. I ran the machine for 25 mins straight at feedrate and rapid at 100 with a back and forth x travel (no cutting) and it never missed a beat, but the steppers were cold to the touch. Shouldn't they at least be warm?
I have a 48vdc, 25 amp power supply and the max draw with all 3 axis jogging at max is .38 of a amp.
My x and y are rated at 4.8 volt @ 2.53 amps. I'm running them at full winding.
My current set resistor is 10k. Should i give them more juice?
Chuck
Aspire, VCPro, PhotoVCarve, Cut3D, Mach3, Home built CnC.
If my calculations are correct, you need ~26K resistors to get 2.5a. So your getting less than 1/2 the rated torque of the motors. You might also want to look at increasing the voltage, but it's a lot easier to increase the current first. Double check my calculations, though.
Gerry
Mach3 2010 Screenset
http://home.comcast.net/~cncwoodworker/2010.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
48 Volts / 26K = 2.? milliamps
You'll need something like 22 ohms at 150 watts.
The formula in the Gecko docs says (47*2.53)/(7-2.53)= kohms. This is the resistor that sets the current on the Gecko, not current limiting resistors.
Gerry
Mach3 2010 Screenset
http://home.comcast.net/~cncwoodworker/2010.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Okay, didn't notice he was using Geckos.
The docs said that if a motor is connected at full winding, the motor's phase current rating is half of its parallel or unipolar rating. I guess the motor label spec's are written at full winding.
My calculations gave me a 11k resister, I went with 10k cuz thats what i had at the time.
Ohm's law says your right so i will stick a 22k in there and see what she can do.
At half the torque it's possible the motor stalled and the result was missing steps.
Thanks again Gerry
Aspire, VCPro, PhotoVCarve, Cut3D, Mach3, Home built CnC.
The Gecko white paper (I think the last one on the site) said the calculations were for full windings.
Gerry
Mach3 2010 Screenset
http://home.comcast.net/~cncwoodworker/2010.html
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
I ran the numbers also and came up with what ger21 came up with, 26.6K ohms for the resistors.
If it's not nailed down, it's mine.
If I can pry it loose, it's not nailed down.
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