Makerbot Thing-O-Matic with MK7, Gen 4 Electronics, 1/8" Aluminum Heated Print Bed ( Polyimide Covered)
- Printing ABS: ~108 Watts
- Printing PLA: ~76 Watts
- Idle: ~10 Watts
- 8 Hr. Print in ABS @ 7cents per kwh: ~$0.06
- Forgetting to disable stepper motors over the weekend: ~$0.23
POWER USAGE STATISTICS
This data is applicable to the currently shipping (Oct 2011) Makerbot Thing-O-Matic
(Power for a process is calculated by subtracting the Idle power from the metered power for the process)
Idle - 10 Watts
With no stepper motors, fans or heating elements active the machine pulls approximately 10 watts
Z Axis Jog - 2 Watts
A jog on the Z Axis activated from the control panel registers 12 watts. Subtracting idle: 2 Watts
Stepper v3.3: PFD = 1.98, RC1 = 0.94, REF = 0.39, RC2 = 0.94
XY Jog - 12.75 Watts
Disabling motors after a Z Axis Jog and Jogging X and Y registers 22.75 watts. Usage: 12.75 Watts
Stepper v3.3: PFD = 2.00, RC1 = 0.94, REF = 0.58, RC2 = 0.94
Enable - 34.75 Watts
Activating Enable from the Control Panel in Replicator G registers 44.75 watts. Usage: 34.75 Watts
MK7 Extruder Forward - 13 Watts
Running the Extruder Forward without filament loaded registers 23 watts. Usage: 13 Watts
Stepper v3.3: PFD = 2.32, RC1 = 2.00, REF = 0.73, RC2 = 0.93
MK7 Extruder Fan - 1 Watt
With only the MK7 Extruder Fan running a power meter will read 11 watts. Usage: 1 Watt
MK7 Hotend 220C Temperature Hold (18C Ambient) - 46.5 Watts
Direct measuring for the average power required to maintain temperature is impossible as even with PID the control mechanism is still rather Bang Bang. An average power reading was obtained by leaving the Hotend at temperature for a period of time while measuring Kilowatt Hours (KWH) and then dividing by the length of recorded time. Calculated Average Power registers 56.5 watts. Usage 46.5 Watts
PID: P = 15.0, I = 0.4102, D = 4.0
Heated Bed 100C Temperature Hold (20C Ambient) - 41.75 Watts
Similar to the Hotend measurement, power is calculated from a measure of (KWH) divided by the length of recorded time. Calculated Average Power Registers 51.75 watts. Usage 41.75 Watts
PID: P = 12.0, I = 0.3242, D = 36.0
Heated Bed 50C Temperature Hold (20C Ambient) - 12.25 Watts
Similar to the previous Heated Bed measurement, power is calculated from a measure of (KWH) divided by the length of recorded time. Calculated Average Power Registers 22.25 watts. Usage 12.25 Watts
Heated Bed Preheat 11C - 100C (120mm X 120mm Polyimide Covered)
This graph shows the relationship between the power consumed and the temperature of the heated bed as it reaches an operating temperature of 100C.
MK7 Hotend Preheat 18C - 220C (No Filament)
Similarly, this graph shows power and temperature versus time for the MK7 heating up to 200C. Notice for both graphs how once a stable temperature is reached (Steady State Error) the power fluctuations become dramatic as the heating element turns off and then on again attempting to maintain the target temperature.
Printing Runtime Stats (1.75 PLA4043D)
This graph shows the Thing-O-Matic's power draw during a print. Data was only recorded for 3 minutes as once the heating elements reached temperature and the printer began printing (125s) power fluctuations made instantaneous values of power meaningless.
Observations however, showed:
- Predominant Power Draw (~84% of print time): 62 Watts
- Peaks (~6-8s apart): 140, 128 and 75 Watts
Calculations from total Kilowatt Hours of PLA and ABS showed:
- Averaged Power Draw PLA (MK7 = 200C, Heated Bed = 50C): 75.75 Watts
- Averaged Power Draw ABS (MK7 = 220C, Heated Bed = 100C): 107.75 Watts
Calculating Energy Costs
Take the Power of what you want to calculate in Watts, divide by 1000, multiply by the number of Hours it occurs and then multiply by your Energy Costs per KWH.
Cost = ( Power / 1000 ) * Hours * Cost per KWH
example: 12 Hour Print job in ABS at 7 cents per kilowatt
Cost = 107.75 /1000 * 12 * $0.07 = $0.09051 or ~9 Cents
ABS vs PLA
The different power requirements between printing with ABS and PLA were surprising. Though not that surprising if you look at the difference in power it takes to keep the heated bed at 100C compared to 50C. And really, one can print just fine without a heated bed altogether which would reduce the required power by another 12 Watts.
While not nothing, the overall energy costs of printing aren't so great as to be a major barrier when compared to the cost of sourcing suitable plastic filament (make sure the plastic you are buying has a consistent diameter as this will decide the upper limit of your print quality). Also consider, stepper motors draw the same amount of power regardless of how fast they are turning, just so long as they are enabled. So then the costs to watch out for are those that come from leaving a powered up machine unattended for long periods of time, or worse, playing about in the control panel and then leaving for a long weekend without remembering to disable the motors.
CONSIDERATIONS AND CAVEATS
This data was collected using a Ryobi E49CM01 of which there is limited information regarding how EXACTLY it takes measurements. It is probably not True RMS though it is doubtful the waveform from mains deviates too far from sinusoidal or has a power factor to the degree that it would significantly alter measurements. For our purposes the manner in which it measures power is most likely acceptable. The real question is how OFTEN it takes measurements. During printing, the power fluctuates quickly enough that a very short power spike could potentially be missed by the meter. By all accounts the meter did an adequate job registering short changes in power. There is an option to display cumulative power consumed which was used to calculate the average power consumption for processes involving lots of fluctuations. The next step will be to open up the meter to see if there's more to be learned about how exactly measurements are taken or explore the possibility of downloading real time data directly from the device.
It is also very important to note that actual energy use of your machine will vary based on factors such as differences in assembly of the Extruder and Heated Bed, PID settings, Surface Area of the First Layer of your Print, Stepper Driver potentiometer settings and Ambient temperature.
Open Office Spread Sheet - TOM Power Consumption.ods