Stepper motors - now starting to collect parts

Hi all,
Now collecting parts to build....
Could someone help me and tell me weather the steppers in the link below will be ok for a Prusa i3 please.
[www.aliexpress.com]

I will be using these for the XYZ and a Greg's extruder running them off Pololu A4988 and Ramps 1.4.
Also can I run two steppers off the one stepper controller(for the Z axis)

Regarding the Gregs extruder. I'm looking for someone to supply this complete. Can anyone help?

Thanks
kcnc
New Plymouth

I see that they are Step Angle(degrees): 0.9

There is no need for 0.9 vs 1.8 degree steppers. It wont help your resolution and will limit you max speed (as you need to send twice as many step pulses). They will work however.

3700g.cm also concerns me

"ideal stepper is NEMA17 size, rated 1.5A to 1.8A or less, 1-4 volts, 3 to 8 mH, 62oz.in (0.44Nm, 4.5kg.cm) or more of torque, 1.8 or 0.9 degrees per step (200/400 steps/rev respectively), for example the kysan 1124090/42BYGH4803 or the rattm 17HS8401"

ie 4500g.cm or better is recommended

Hi Dust,
Thanks for the info. Now looking agin at the steppers...lol
So can I run two steppers off the one stepper controller(for the Z axis).

Another thing is the hotend do you know any available here in NZ at a good price/quality?

kcnc

yes you can run two stepper motors of the one driver for the Z axis. on the ramps board there is one dual header 4 pin that is wired to the one board where the others are only wired to a single 4pin header. this one you wire to your z motors

Right had another look at steppers
Found these:
[www.aliexpress.com]

But can't find out what voltage they are.
Does anyone know???

kcnc

RATTM is one of the recommended steppers, cant remember what voltage, but current is more important.

These are what I am running on my I3.

Yes you can run 2 steppers off one drive. You must watch the current requirement though. The driver can only supply 2A max with fan cooling and 1A max without fan cooling. So if you have stepper motors capable of drawing more than 1A you have to wire them in series. If you use the two connectors on the RAMPS board you are wiring them in parallel and you will overload the driver.

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[www.makershop.co.nz]
Makershop - Reprap parts, adding new stock almost daily.
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My Z steppers are 1.7 amp and are fitted in parallel on my Ramps. (actually,all my motors are 1.7A) They have been running all year and my Pololu chips don't suffer from overheating - in fact, I ran them without a fan initially. Also, my motors, get barely warm.

Incidentally, the supplier I bought them from has a big discount starting today on the very same motors I bought there before - looks like they will be US $56.56 inc shipping for a set of 5!

[www.aliexpress.com]

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Waitaki 3D Printer

Hi Waitaki,
That ali-express link is a perfect example of why I've always been 'apprehensive' with ali-express...
The description clearly specifies 42BYGHW609 and yet the attached photo clearly has steppers with a 42BYGHW811 sticker on them.
I'd guess that there's a 30% chance of receiving the expected 42BYGHW609 motors. Another 20% change of receiving 42BYGHW811 motors, 40% chance of receiving some 'random' motors that happen to be 'about the right shape', and 10% chance of receiving nothing at all...
OK, perhaps I'm being a little cynical... LOL

Hey Waitaki, do you know what current you are putting through your steppers? If they are barely getting warm then it is probably very low. Probably less than 1/2 their rated current. That's perfectly OK. I usually recommend no more than 70% of the rated current to my customers. Any higher than this and the motors get hot enough to melt any PLA parts you bolt them to. Lower current also makes for a more quiet machine.
For those of you not up with electronics the heat is proportional to the current squared but the torque is proportional to the current (roughly). That means if you double the current the motor gets 4 times as hot. Or if you run the motor at 70% current you get 70% of the torque bt only 50% of the temperature rise.



waitaki Wrote:
-------------------------------------------------------
> My Z steppers are 1.7 amp and are fitted in
> parallel on my Ramps. (actually,all my motors are
> 1.7A) They have been running all year and my
> Pololu chips don't suffer from overheating - in
> fact, I ran them without a fan initially. Also, my
> motors, get barely warm.
>
> Incidentally, the supplier I bought them from has
> a big discount starting today on the very same
> motors I bought there before - looks like they
> will be US $56.56 inc shipping for a set of 5!
>
> [www.aliexpress.com]-
> Wantai-4-lead-Nema-17-Stepper-Motor-42BYGHW609-340
> 0g-cm-48-oz/599005546.html

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[www.makershop.co.nz]
Makershop - Reprap parts, adding new stock almost daily.
+++++++++++++++++++++++++++++++++++++++++++++

Hey REVVA, have you had a bad experience with a Chinese supplier? If so, please tell us about it.
It is not unusual for Chinese online retailers to post a picture that does not quite match the description. In most cases it is not deliberate. In fact, I can't recall ever getting the wrong goods. But of course,no-one is forced to shop in China - we all make our own choices.

Hi MikeP,
I haven't measured the current the Pololu's are sinking but I can recall setting the voltage to around 0.45v or thereabouts. I have this "theory" that the more stable and robust a machine is built, the less stress on the motors?! That's why I built my printer like a brick sh**house..

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Waitaki 3D Printer