Dual extrusion heat/cool speed calibration

[airbrett 0]

I'm working with a delta with a E3D Chimera+ hotend. I'm looking to more accurately calibrate the values for the following settings:

 

machine_nozzle_heat_up_speed
machine_nozzle_cool_down_speed

 

Here is what I tried (beyond guessing): For machine_nozzle_heat_up_speed I tried preheating the hotend to 175 (the idle temperature I am using), starting a timer then setting the temperature to 215 (my printing temperature). Then calculating the value by (215 - 175)/TimeMeasured. I did the process in reverse for machine_nozzle_cool_down_speed. While this is an overall improvement, I'd like to see if it can be improved. Is there better method for homing in on the values for these settings?

 

Thanks