1.8 degree or 0.9 degree steppers

Hello forum..this is my first post on RepRap, and i was hoping,
could someone please help a keen reprap newcomer and verify if I can use these motors:

These are size 17 motors, with a Body length 31mm.
Stepper Motor Model ETS535
Step Angle: 0.9 Deg
Rated Current: 0.425
Voltage:4.25V
Phase Resistance: 10 Ohm
Phase Inductance: 8.5 mH
Holding Torque: 7.5 Ncm (Bipolar)
Detent Torque: 0.4 Ncm
Rotor Inertia: 15 g.cm>2
Shaft configuration: Single with thru-hole near spigot
Shaft Daimeter: 5.0mm
No of Leads: 4 150mm long
Weight: 210 g each

with Arduino mega and Pololu stepper drivers.. Thank you ...

0.9deg steppers in general are fine (just remember to double the steps_per_mm setting), but these particular ones don't have enough torque.

Thank you Rebecca, after your advice about the lack of Torque I have sourced some Steppers
directly from reprap.org Prusa build page from ZAPP...

Thank you again.....
Andrew

Was just pondering the same question. Phidgets has 2 very similar Wantai motors
The 1st is on the list of motors on the Stepper Motor page : 42BYGHW811 [www.phidgets.com]
Step Angle 1.8°
Holding Torque at rated current 4800 g-cm
Low Speed Torque 4240 g-cm
Coil Resistance 1.25 Ohms
Rated Current 2.5A
Maximum Speed 600 RPM @ 12V (no load)
Weight 332g
Number of Leads 4

The other is 42BYGHM810 [www.phidgets.com]
Same specs except:
Step Angle 0.9°
Low Speed Torque 4280 g-cm
Coil Resistance 1 Ohm
Rated Current 2.4A
Weight 362g

The price is exactly the same - $14.55 USD ea or $14 @ qty 5.


Not sure why I wouldn't choose the 0.9° stepper. Any drawbacks I'm not thinking of?

Wow, no opinions on an internet forum? That must be a first.

... it's a frequently question, answered several times now - so the motivation to answer one more times isn't really big

From the technical side - the 0.9-deg motor is more accurate than the 1.8-deg, but also slower with the same clocking speed.

I'll prefer the 0.9-deg type, though ...

---

Viktor
--------
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Either motor from phidgets works fine, 1/16 microstepping on a 0.9* may be too much for your micro to handle unless you have something more powerful than an Arduino.

I am anxiously awaiting the arrival of my 0.9 deg step motors from Phidgets. From the reading I've done, some boards have difficulty keeping up with the calculations if you use a 0.9 deg step motor with 1/16th microstepping, as WildBill mentioned. However, microstepping tends to be slightly less accurate than full steps of comparable size (for example, a full step of a 0.9 deg motor will be more accurate than a 1/2 micro-stepped 1.8 deg motor), so using a 0.9 deg motor with 1/8th microstepping will be more accurate than a 1.8 deg motor with 1/16th microstepping, even though the resolution will technically be the same. Which is why I went with the 0.9 deg motors.

Additionally, this means that if the latest and greatest electronics of the near future end up with faster processors (I'm looking at you, Adruino Due) and newer drivers with 1/32 stepping (I'm looking at you, DRV8825), I may be able to reap the benefits without having to replace my motors as well.

i assume u are driving them with stepsticks? ...

well i think i am trying to figure out how accurate/consistent 1/16 steps can be, after reading up lotsa stuff about them esp from nophead ...

check out the 2nd half of this thread [forums.reprap.org]

maybe you can try your own test and post some vids. i am curious to know, how diff stepsticks match with diff steppers ...