Miniature extruder?

Has anyone attempted to go sub-NEMA14 for an extruder?

I've seen [www.thingiverse.com] (28BYJ-48 stepper motor but the gears are plastic) but I don't see any video or further update about it working or not.

Has anyone tried any of these steppers for an extruder yet?

---

"12V 4-phase 5-wire stepper motor 28BYJ-48-12V"

Diameter: 28mm
Voltage: 12V
Step angle: 5.625° x 1/64
Reduction ratio: 1/64
Weight: 30 grams
Shaft: 5mm
Gears are usually made of plastic.
Steps per rotation: (360°/5.625° = 64, multiplied by 64 with the gears) 4096 steps

Please note there is two versions of the 28BYJ-48: 5V and 12V. Some of them also have very weird gear ratio, listing 512 steps per rotation but really are 513 steps, other people have calculated fractional ratios, etc. And if we go by the specifications listed by the seller, it seems the 12V has a different ratio.



[www.ebay.ca]

---

"DC5V 2-phase 4-wire Gear stepper motor Full Metal Gear Stepper Motor"

Specification:
Step Angle: 18° / 100
Reduction ratio: 100:1
Phase Resistance: 12 Ohms
Voltage: 5V
Weight: 15 grams
Shaft: 3mm
Gears are made of metal.
Steps per rotation: (360°/18° = 20, multiplied by 100 with the gears) 2000 steps

Wiring Connection:
Red: A +
Orange: B +
Black: A-
Brown: B-



[www.ebay.ca]

---

"DC 5v 6V 2-phase 4-wire Stepper motor full metal gear box Planetary geared motor"

Phase resistance: 6.5Ohm
Current: 6V short-circuit current 0.85A
Motor step angle: 18 degrees
Reduction ratio: 1:45.25
Weight: 70 grams
Shaft: 4mm
Gears are made of metal.
Steps per rotation: (360°/18° = 20, multiplied by 45.25 with the gears) 905 steps



[www.ebay.ca]

---

"Copper Shaft Coupling Coupler 2mm/2.3mm/3mm/3.17mm/4mm/5mm Motor Transmission"

Weight: ~5 grams

Since the drive gears for extruders always seem to be for 5mm shafts we could use this coupler for the two steppers above with the 3mm and 4mm shafts. I would prefer to use some king of "ring" adapter with a hole for the set screw, but I cannot find that. If either of the last two steppers becomes popular enough for lightweight extruders, maybe people will start making drive gears with the appropriate 3mm/4mm hole. In the meantime we can use those couplers. They're a bit long but most of us don't have lathes and must use whatever we can find.

Then again maybe the steppers won't last long with side pressure on their shaft and we'll need to use a coupler anyway with bearings on the 5mm rod for the regular drive gear?



[www.ebay.ca]

---

Since Nophead seems to have the tools required and is always meticulous in his testings, maybe he could make MK7 or MK8 drive gears with the 3mm and 4mm holes to test these two steppers himself? Or test with the couplers to avoid side pressure on the motor shafts? In either case I would trust his experience and his results far more than my amateur attempts.

Edited 19 time(s). Last edit at 01/07/2015 10:55AM by Yvan256.

Ho cool, thats exactly the stepper that i recently found and i want to test it also.
The good thing ist that the 28BYJ-48 already has a 5mm shaft and is only 30grams light.

Chri

---

[chrisu02.wordpress.com] Quadmax Intel Delid Tools

Note that 5-wire stepper motors are not suitable for use with standard Pololu and similar stepper motor drivers. Choose a 4 or 6 wire stepper motor.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
Note that 5-wire stepper motors are not suitable for use with standard Pololu and similar stepper motor drivers. Choose a 4 or 6 wire stepper motor.

thats not good to hear, however the stepper i`ll get is already shipped with a daugtherboard based on the IC ULN2003A, i found some documentation about it to wire with 4 signals wires to a Raspberry PI , so i hope it will work also for a reprap electronics.

Chri

Edited 3 time(s). Last edit at 01/08/2015 05:33AM by Chri.

---

[chrisu02.wordpress.com] Quadmax Intel Delid Tools

If there is any way that you can get the step/dir signals from your boards, I already have the code to drive a ULN2003 in full step mode (two coils at the same time, it's a lot stronger) using an ATtiny84 or ATtiny861 (can't remember which one).

edit: convert your 28BYJ-48 to a bipolar motor, it's even easier. The author reports 800 g/cm but I have no idea if this is sufficient for even a low-end extruder for slow prints and I can't find any numbers on the wiki page about extruder motors. If anyone reading this knows if 800 g/cm is enough for a 1.75mm extruder, please reply.

Edited 2 time(s). Last edit at 01/08/2015 10:20PM by Yvan256.

The ULN2003 is a rubbish stepper motor driver, only suitable for low speeds, and without current adjustment (because it's a constant voltage driver, not constant current). Also in 5-wire stepper motor, at most half of the windings are active at a time, so the maximum torque is less than that of a similarly-sized 4-wire stepper motor.

Converting the 5-wire motor to 4 wire sounds like a good option, in theory all you need to do is to break the link between the two centre taps. But you will need a higher driving voltage to get maximum torque.

Edited 3 time(s). Last edit at 01/09/2015 11:26AM by dc42.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
Yvan256
"DC5V 2-phase 4-wire Gear stepper motor Full Metal Gear Stepper Motor"

Specification:
Step Angle: 18°
Reduction ratio: 100:1
Phase Resistance: 12 Ohms
Voltage: 5V
Weight: 15 grams
Shaft: 3mm
Gears are made of metal.
Steps per rotation: (360°/18° = 20, multiplied by 100 with the gears) 2000 steps

Wiring Connection:
Red: A +
Orange: B +
Black: A-
Brown: B-

[www.ebay.ca]

Using an L293D IC, 5V and basic code running on an ATtiny85 with a long enough delay between coils change to get somewhat decent torque without stalling (1500 x __builtin_avr_delay_cycles at 1MHz, not sure how long this is in seconds), I was able to get around 12 revolutions per minute with this motor. Next step is going to be testing this same motor but with an A4988 stepper driver and 12V, however I'm not sure what the current limit should be. Of course we could also switch to a "MK8" drive gear which has an even smaller diameter in contact with the filament. If that's still not enough, then we could go with a custom-build drive gear with an even smaller diameter since the shaft is only 3mm.

I compared the rotation speed with a Wade's geared extruder and it seems to me like it would be fast enough.

If we consider that an average NEMA17 stepper is around 300 grams, this one is only 15 grams, i.e. around 20 times lighter.

Possible uses would be ultra-compact extruders for portable printers (Tantillus, FoldaRap, etc) and multi-colours/multi-materials printers.

Edited 5 time(s). Last edit at 01/11/2015 06:23PM by Yvan256.

Quote
Yvan256

Quote
Yvan256
"DC5V 2-phase 4-wire Gear stepper motor Full Metal Gear Stepper Motor"

Specification:
Step Angle: 18°
Reduction ratio: 100:1
Phase Resistance: 12 Ohms
Voltage: 5V
...

Next step is going to be testing this same motor but with an A4988 stepper driver and 12V, however I'm not sure what the current limit should be for this stepper.

As it specifies 5V and 12 ohms per phase, the A4988 current should be set to at most 5/12A per phase = 417mA.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
As it specifies 5V and 12 ohms per phase, the A4988 current should be set to at most 5/12A per phase = 417mA.

So 12V and 417mA? Is there a way to test, measure or set this 417mA?

If you will be using a standard stepstick driver board, then the current is defined by the voltage on the pot wiper, which you can measure with a multimeter. Read the driver manual to determine the relationship.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
If you will be using a standard stepstick driver board, then the current is defined by the voltage on the pot wiper, which you can measure with a multimeter. Read the driver manual to determine the relationship.

Ok, thank you.

Edited 1 time(s). Last edit at 01/12/2015 09:56AM by Yvan256.

i got my steppers recently, and made a test with them connecting directly to a 3D electronics.
Before that i cut the 5. wire internaly at half so its now a 4-pin Stepper.
But the result was not very good, it only was turing around when i had to help a little bit with my fingers, and its always turning in the same direction, doesn`t matter if i say move forward or backwards.
i also tried serval microsteppings and full-stepping, with different vRef`s but no luck.

probably the stepper really will only as it should with the electronics board witch which it came,or changes at marlin, but i don`t know what i would have to change there
I`ll have to test this later some time.

Chri

---

[chrisu02.wordpress.com] Quadmax Intel Delid Tools

If only steps in one direction, that suggests that the wiring is not correct, or just possibly that the driver is faulty. It should not need any firmware changes, other than possibly a configuration change to limit the maximum speed and/or acceleration. Have you checked the resistance across each of the 2 phases of the motor, and verified that you have no continuity between them?

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I just measured the coils again, it seem`s that i already have blown one coil

Chri

---

[chrisu02.wordpress.com] Quadmax Intel Delid Tools

Quote
Chri
I just measured the coils again, it seem`s that i already have blown one coil

Chri

Maybe you were just unlucky, or maybe you had the driver current turned up too high. Assuming you cut the correct wire, of course. What printer electronics were you using?

To set the current on a Pololu or StepStick driver, you need to adjust the potentiometer to give a voltage at the test point or potentiometer wiper of either 0.4 or 0.8 or 1.6 times the desired current, depending on whether it is a Pololu driver (0.05 ohm sense resistor), a high-current (1.5A) stepstick (0.1 ohm), or a normal stepstick (0.2 ohm). That's according to [reprap.org].

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

i think the Vref was too high, is disassembled the stepper and found out that the wire of the spool became loose on one soldering, i`ll try to fix it, but i have bought two steppers, so if it will not work i can move on on the 2nd one.

I have testet it on a Gen6 Deluxe (only 1/8 step available) and on a Sanguinololu with serval steppings.

Chri

Edited 2 time(s). Last edit at 01/18/2015 04:41PM by Chri.

---

[chrisu02.wordpress.com] Quadmax Intel Delid Tools