# Cartesian Printer – Power Usage

One of the most important components is the power supply. The standard output voltages  used for 3d printer power supplies is 12v and 24v. 12V Power supplies are much more common and is abundant in the from of atx pc psu’s. This abundance typically makes a 12v power supply cheaper. But there are some downfalls to a 12v system in comparison to a 24v system. Mainly you have to have double the current in a 12v system in comparison to a 24v system to achieve the same wattage. Thicker gauge wires are required for the 12v system due to the higher flow of current. A few benefits of the 24v system is faster heatbed and hotend heat times plus the increased torque from a correctly selected stepper motor. From searching forums i have found that many people have had increased performance from their system by switching from 12v to 24v. Downside to 24v is that it is harder to find suitable power supplies and 12v is a more commonly used voltage for 3D printer electronics. I will need to find the compatibility of the electronics with the use of 24v.

A suitable power supply wattage must figured out to insure safe operation of the printer.

Typical Wattage for main components that will used in this build:

• 2x E3D V6 24v 40w = 80w
• 2x 17HS24-1206S – Finding Maximum wattage for the stepper motor is a little more tricky. We know that Power = Torque times the Angular Velocity. First the angular velocity has to be found. Say that the maximum velocity of the bed is set to 50mm/s which is 0.05m/s and the diameter of a typical drive pulley is 14mm which is 0.014m in diameter. Rpm = (Velocity/(pi* Diameter))*60 = (0.05/(pi*0.014))*60 = 68.21. To find angular velocity: ((2*pi)/60)*68.21 = 7.14 rads/second. The torque of the 16HS24 – 1206S Nema 17 Motor is 65Ncm which is 0.65Nm. Finding power: Power = 0.65*7.14 = 4.64 Watts @ 100% Efficiency and no torque losses due to higher rotational speed. With a safety factor of 2: 4.64watts * 2 = 9.28watts ~ 10 Watts.   2 Stepper Motors: 2*10 watts = 20watt
• 4x NEMA 17 42STH47-1684AC 4*10 watts = 40 watts
• 300mm * 300mm Silicon Heat Bed = 300 watts

Total Wattage: 80 + 20 + 40 + 300 = 440 Watts .

600 Watt supply would give enough power with a safety margin of 160 Watts.

I have researched a lot on finding a 24v 600watt power supply. From my research it seems that the meanwell switch mode power supply is the most reputable. But i couldn’t find any at a reasonable price. One of the cheapest solutions found was using two power supplies.

Power Supplies:

• 24V 350W Power Supply – £25 Pound
• 24V 250W Power Supply – £21.25 Pound

The 350W  Power supply would be used for silicon heat bed and the 250 watt Power supply would be used for the rest of the electronics.

Found a meanwell 500W 24V 21A  RSP-500-24 for £20 pound on ebay. Problem is that they may run out of stock soon.

Time to do even more research