Stepper Motors for Custom made Ultimaker Original

3BRBS · August 16, 2016

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!

Edited August 17, 2016 by Guest

gr5 · August 16, 2016

I'm not a stepper expert. This is really not my expertise. I am an electrical engineer but specifications for these things is complex. I'm pretty sure any of those steppers would work. The 1.8 degrees is not critical (200 steps per rotation). You could do double or half that and all you really have to do is change the configuration.h file to setup the proper value for steps/mm. However if you have too many steps then you can't go as fast. With the current design the XY steppers can only go up to a little over 300mm/sec which is much faster than anyone would want to print at anyway. In other words arduino can put out up to exactly 40,000 steps per second and no faster.

I wouldn't worry too much about voltage specs. Steppers are tough as hell. The current specification I would worry a bit - higher current implies more heating at the stepper driver and those can burn out. Although if you burn one out they are very cheap - around 10€ or $10 USD. But the steppers themselves should be fine. My steppers get very hot - sometimes around 70C, yet they work fine.