0.9° vs 1.8° steppers.

I've read some info saying real world there is no real difference in term of print quality. I'm curious what others have experienced. I'm gearing up to build a second printer and the 1.8° steppers are a better price. Just wondering if the 0.9° steppers are worth the premium.

Nope! Almost no reason to use .9° ones unless you're gearing them up something crazy.

I think that if you would use a machine like this one: [reprap.org] it might benefit.

If you use long arms, the movement is amplified by the length of the arms, but in all other cases, I can't really come up with a reasonable explanation why 0.9º would be better than 1.8º

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http://www.marinusdebeer.nl/

The difference is not about quality. 0.9° steppers cost more because they're more complicated to manufacture and they're not sold as often. Use 0.9° steppers if you need it. It depends of your printer's architecture. Except some specific uses, like scara arms; like said above, extra resolution must be consistent all over each component of the machine. The stepper don't have to provide a resolution which overtake other components resolutions. If one component, from motor to nozzle, is not capable to reach a comparable resolution as other, the overall resolution of the machine will level with the less precise component's one.

For example, if you use standard 5mm metric screws on your Z axis, the resolution of a 1.8° motor will be theoricaly 25µ/step. No need to get a 12.5µ resolution to print at last 100µ layers. I said theoricaly, because the threaded rod and the nut are far away to be machined to reach that precision, just like the rods and bearings.

Second example, you drive the same Z with a GT2 belt and 20 tooth pulleys. The resolution of a 1.8° motor will be 200µ/step. Theoricaly you could print 200µ layers, but with an average quality (rather be at last 2 times the wanted precision). In this configuration, a 0.8° motor will give you a 100µ/step resolution, so you'll be able to print properly 200µ layers.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

... this discussions are really often and mostly pretty useless - but in contrary to the common mind -- 0.9° are better than 1.8° in accuracy because of the finer step-pitch!

The mechanical accuracy of a stepper is defined by angular displacement from a fullstep-position in respect to applied force/torque ... and microsteps don't change this.

So for higher positional (torque-related) accuracy you'll need 'smaller fullsteps', what's given with the 400-step motors compared with the 200-step types.

So in the praxis, a 0.9°-step motor at fullstep is more accurate/precise than a 1.8°-motor with half-stepping ... and this relation is the same for finer microstepping too ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Yep, 400 steps is more precise than 200, hopefully ! Viktor, note in my calculations, I did not count microstepping, because microstepping angle is precise only on the step and on the half step, intermediary steps are close but not precise. That means 400 steps and 200 with half step microstepping have the same angle precision. You're absolutely right but beyon the half step.

Edited 1 time(s). Last edit at 01/24/2015 12:53PM by Zavashier.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

A 0.9^o stepper should be better than a 1.8^o stepper, but that doesn't mean that it will be. For example, if the rotor concentricity to the shaft is not as good in the 0.9^o as in the 1.8^o then it may not be as accurate.

Having said that, I have only had one stepper motor that was not accurate and linear. For my next 3D printer I will try out 0.9^o steppers.

Quote
Zavashier
Yep, 400 steps is more precise than 200, hopefully ! Viktor, note in my calculations, I did not count microstepping, because microstepping angle is precise only on the step and on the half step, intermediary steps are close but not precise. That means 400 steps and 200 with half step microstepping have the same angle precision. You're absolutely right but beyon the half step.

... it's a bit more complex though - I have some 3-phase steppers with drivers, that can be reconfigured to 200, 400, 800 and 1000 fullsteps(!) per rev. and the driver provides 10x microstepping too, so the step count changes to respective 2000 ... 10000 microteps.

In the datasheet the accuracy is given for the 1000 fullstep mode, but identical for all other modes too - see the attached data-sheet:

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

That Schneider motors are very specific ones. My provider sells them 2380€ exl.VAT each. Of course you can find stepper motors with high resolution per revolution, and some able to reach high speed without loosing torque. The kind I select at work, and maybe you do too. Frankly speaking we both know they're totaly out of interest for any reprap For anyone interested in microstepping and angle accuracy, I recommend the excellent work of Pr Douglas W. Jones.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

... my motors are from Precitec or Berger-Lahr - seems Schneider acquired the company and rebranded them?

I have steppers and microstepping drivers from different other vendors too, but didn't notice big differences in the behaviour or accuracies compared to other 400- or 1000-steps-per-rev motors ... could be, it's more the difference between older standard or high quality motors and modern cheap chinese manufacturers?

And for the RepRap-ability or DIY-relation -- I'm using them for my 'RepStraps' and all sorts of DIY-projects

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Luxury Reprap, who cares ? I know this motors under Schneider, but they're imported, so maybe name changes abroad... About accuracy, our FDM machines are far away to allow us to see any difference anyway. But for more precise machines that matters.

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

... my first DIY-3D-printing was not with FFF (FDM), but LOM-fabbing with 3W CO2-lasers around 1990 - then with common steppers+drivers and 0.025 mm accuracy, what was sufficient ... but then I've worked in the micro-/nanotech industry some ten years, so 'used' to be much more accurate

My actual reworked CNC-mill based laserengraver has 0.0025 mm resolution and the plans for the next machines (laser- and micro-3D-fabbing) targets sub-micron resolutions ...

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Congratulations ! I'm dying to see those in action. Appreciate most of reprappers are far to reach that precision, so do I My large CNC mill reaches only 0.1mm (was engineered for this purpose), but at high speed 22m.mn on a large area (3000mm on X). Different worlds...

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Collective intelligence emerges when a group of people work together effectively. Prusa i3 Folger (A lot of the parts are wrong, boring !)

... you can find some infos here - [forums.reprap.org]

Attached some images from my 'medium'- and 'micro'-sized lasercutting works

The micro-3D-printing was mostly under NDA, so no images made ... but here I've stacked layers made from ceramic sheets, metal pastes and 10 micron thick platinum or 25 micron thick gold wires to form 3D-structures for sensors.
See here the image under "brazing / hard soldering" - this is an excerpt of one of the sensors ...

Edited 1 time(s). Last edit at 01/26/2015 04:18AM by VDX.

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

A .9 stepper can make a big difference in print quality as the extruder stepper. If you are using a 1.8 stepper with a non-geared extruder and a good hot end like the E3D, the steps will show in the extrusion as a slight pulsing, even at 1/16. This manifests in the surface of the print as a rough moire pattern. Tuning the Vref can minimize, but not eleminate it. Using an 8825 driver that can do 1/32 microstepping will accomplish the same thing, but if you are stuck with non-removable drivers (as on the Printrboard) then a .9 stepper will provide the needed boost in extruder resolution.

By the way, I found this:
[www.robotdigg.com]

$9.80 per stepper motor... Not that expensive for a 0.9º right?

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http://www.marinusdebeer.nl/