Cura time calc not accurate

The print time estimate I have in Cura 15.04.6 is always less than actual print time.
Typically actual print time is +20%
Had this all time even after first time calibrating parameters.
Any way to easy calibrate this ?
Any code to help out ?
Thanks

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

In one of the printer config files there is a specification for acceleration and jerk. If you enter those parameters to match your printer the time will be more accurate. A web search for "Cura print time" will probably yield the details.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I have these values in my Configuration.h
Are they decent ? I find others that have much higher values ....


#define DEFAULT_AXIS_STEPS_PER_UNIT {80,79.59,4157,670} // default steps per unit for Ultimaker
#define DEFAULT_MAX_FEEDRATE {400, 400, 2, 45} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {450,450,100,10000} // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for Skeinforge 40+, for older versions raise them a lot.

#define DEFAULT_ACCELERATION 450 // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 450 // X, Y, Z and E max acceleration in mm/s^2 for retracts

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

Thanks for info. I found link below very useful .

Link

Also had me finally upgrade my Cura to latest version.
Lot of new good stuff there

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden