Hi all! I'm building an Ultimaker Original from scratch so it's custom made, I'm also not electronic savy at all. The final hardare I need to purchase are the stepper motors. I've read a lot of information posted here and in other forums, and I came to a number of motors that seem adecuate for purchasing for my Ultimaker. The original specs for the stepper motor from the BOM of the Ultimaker Original are as follows: Step angle (º): 1.8 Temp. Rise (ºC): 80 max Amb. Temp (ºC): (-20~ +50) Nr. of Phase: 2 Insulation Res. (M ohm): 100 min. Insulation Class: Class B Max. Rad. Force (N): 28 Max. Axial Force: 10 Rated Voltage (V): 2.8 Rated Current (A): 1.68 Res. / Phase (10% Ohm): 1.65 Inductance / Phase (20% mH): 3.2 Holding Torque (N.cm): 36 Detent Torque (N.cm): 150 Rotor Torque (N.cm²): 54 Weight (kg): 0.285 Body Lenght: 39 Total Lenght: 63 Total Width: 42.3 Bolt Widht: 31 ±0,2 Meeting this requirements, more or less I found the follwing models: * SY42STH38-1684A: Meets every requirement, but it's very expensive for my budget. * 1703HS168A: Has a higher Inductance/Phase (20% mH) than the original specs, this is 3.6mH v/s 3.2 mH, and a superior Holding Torque than the original specs 4.4 Kg-cm v/s 3.6 Kg-cm * 42SHD0217-24B: Has a superior Rated Voltage (V) 3,75V v/s 2,8V, that comes from a inferior Rated Current (A) (1.5A v/s 1.68A) and superior Res. / Phase (10% Ohm) (2.5Ω v/s 1.65Ω); having also more Inductance/Phase (20% mH) (5mH), Holding Torque (N.cm) (5.0 Kg-cm), Detent Torque (N.cm) (152 gr-cm[?]) and Rotor Torque (N.cm²) (57 gm-cm2). * 17HS4401: Couldn't fin every spec to compare, but it has a lower Rated Voltage (V) which is 2.55V, as a result of a slightly higher Rated Current (A) of 1.7A and a lower Resistance/Phase (10% Ohm) of 1.5 Ω. And also a superior Holding (4.0 Kg-cm) and Detent Torque (224 gr-cm[?]). * OK42STH38-1684A: Meets every requirement, but I was not able to find which company produces this motor, therefore leaving me the impression that its quality is more dubious than all the previous ones. It seems also that is not extremely commons to find. So my questions are: a) Is it relevant that the Inductance/Phase and Holding Torque of the motor 1703HS168A is superior than the original specs from the UM Original? Does or should affect its speed, precision or performance? Will the board (Arduino MEGA Ultimaker Shield v1.5.7) be able to supply enough current to make the stepper motor function properly? b) Is it relevant that the Rated Voltage (V) from the motor 42SHD0217-24B surpasses the original specs from the UM Original? And also, will the board (Arduino MEGA Ultimaker Shield v1.5.7) be able to supply enough current to make the stepper motor function properly? c) Is it relevant for the motor 17HS4401 that the Rated Voltage (V) and Res. / Phase (10% Ohm) are inferior, but the Rated Current (A) superior to specs, and also, does or should affect its speed, precision or performance? I tried to do the job to find out from myself which motor could be compatible, from the ones that do not meet every original spec requirement, but I do not think I found the answer yet, so therefore I am seeking for help here. Cheers and thank you all!