Motor choice?

I'm just getting into 3D printing and will build a wooden repstrap in order to print me a smartrap. So I'm stuck at motors. What should I aim for? Torque? Shaft length? Dimensions? I can get hold of 0.34 Nm motors quite easily - will that do for the extruder?

Not knowing what the weight is of your repstrap
0.34 NM will be fine for horizontal axis.
if the weight aint to much then you could use them also for the Z-axis

What kind of extruder do you have in mind?
A geared extruder can do with less powerful motor, a direct drive extruder needs more power.

If the motors are not to pricey it's always worth a try, you will most likely need more motors in the future. :-)

On the Smartraps I've been building I've been using lower cost Wantai 42BYGHW609 motors. They are a good value and I use them to keep costs low on entry level printers though I've used them on larger machines in the past. These days on the larger machines I use Kysan 1124090. (I also used those on the prototype Smartrap but went for a lower cost motor in the end). They are a bit more robust, more holding torque and larger, longer wire. Depending on the distributor they come with connectors installed. The Kysan are about a third more (in US pricing) with the body being a bit longer. The Kysan are 5.5kg/cm holding torque and the Wantai are 4kg/cm holding torque, still enough to drive 1.75 filament with an MK7 gear on the Smartrap.

When using the Wantai motors on a Smartrap the M4 x 60 screws that help stabilize the base are a bit too long due to the shorter motor. You can either trim the screws or use shorter screws.

I was planning on building a wooden, verrrrry slow direct drive extruder to print a more proper one, but I guess I could opt for a more powerful motor initially. The wood I'll be working with is 1"x½", so it's practically the same weight as the plastic.

What about shaft length? The ones I'm eyeing are 24mm, which I think should work, but I've seen even cheaper motors with much shorter shafts, roughly around 15mm. I guess there are too short?

Oooh, now I found motors with the same dimensions (40mm body and 24mm shaft) with a torque of 0.94 Nm... Might opt for one of them for extruder, then

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loidor

Oooh, now I found motors with the same dimensions (40mm body and 24mm shaft) with a torque of 0.94 Nm... Might opt for one of them for extruder, then

How much current do they consume? and are your pololus up for that task?

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BackEMF

How much current do they consume? and are your pololus up for that task?

Uhm... I guess so? Their specs are 1.7A and 5V, but then I've planned to have fan cooling on the RAMPS board... The motor should be so oversized for the task it would stay quite cool.

The other choice would be one at 0.42 Nm, which rates at 1.7 and 2.8V.

that sounds ok. there are so many different motor specs that it is still not easy to be 100% sure.

Also, if I'm not mistaken I should be able to turn them down to getting about 1A, and they should still have a torque of about 0.5 Nm.

Right, so now it's just that damn waiting for them parts to arrive... Blimey, why is China so far away?

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loidor
Also, if I'm not mistaken I should be able to turn them down to getting about 1A, and they should still have a torque of about 0.5 Nm.

Right, so now it's just that damn waiting for them parts to arrive... Blimey, why is China so far away?

In Australia which is close to China really, it still takes about 5 weeks for the free postage to arrive. If you want it quick, 3-4 days, you have to pay for a courier service and that is very expensive.
If you want good motors cheap and want quantity, try this guy, he has been very helpful to me.
Roy Yan | Salesman | LDO MOTORS | www.ldomotors.com |
| TEL: +86-755-82418663 | Cell Phone: + 86-158-9979-5233|

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

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regpye
In Australia which is close to China really, it still takes about 5 weeks for the free postage to arrive. If you want it quick, 3-4 days, you have to pay for a courier service and that is very expensive.
If you want good motors cheap and want quantity, try this guy, he has been very helpful to me.
Roy Yan | Salesman | LDO MOTORS | www.ldomotors.com |
| TEL: +86-755-82418663 | Cell Phone: + 86-158-9979-5233|

China is on the other side of the planet no matter where you are. Hell, China is even far away when you're IN China, I think.

Thanks for the link, I'll surely check him out!

Why not build a Smartrap from the start? You can buy the plastic parts on eBay or I'm sure someone here on the forums would be willing to print you a set.

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knife-edge
Why not build a Smartrap from the start? You can buy the plastic parts on eBay or I'm sure someone here on the forums to would be willing to print you a set.

Well, first of all I got the wood, and secondly I will remix it a little to get rid of the 6mm rods (these are totally impossible to find around here, and I already have 8mm),and lastly it seems a bit... Too easy. I want to challenge myself and create something from scratch, since that gives me a sense of enormous well-being. =D

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loidor

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knife-edge
Why not build a Smartrap from the start? You can buy the plastic parts on eBay or I'm sure someone here on the forums to would be willing to print you a set.

Well, first of all I got the wood, and secondly I will remix it a little to get rid of the 6mm rods (these are totally impossible to find around here, and I already have 8mm),and lastly it seems a bit... Too easy. I want to challenge myself and create something from scratch, since that gives me a sense of enormous well-being. =D

Hi ioidor, where is around here? you can't be more isolated than me in rural South Australia.

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

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regpye
Hi ioidor, where is around here? you can't be more isolated than me in rural South Australia.

Rural South Australia is like the suburbs compared to foresty Sweden, I'll tell you. ;-)

Or, well, not totally, but since one metre of 6 mm axis rod is worth about 40 Swedish crowns (£4 or something) at the most (might even get it for half that price once I find a bloody seller), there's no way I will pay about 120 crowns for shipping, since I can't get it in my town. I was lucky to score that 8 mm rod locally

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loidor

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regpye
Hi ioidor, where is around here? you can't be more isolated than me in rural South Australia.

Rural South Australia is like the suburbs compared to foresty Sweden, I'll tell you. ;-)

Or, well, not totally, but since one metre of 6 mm axis rod is worth about 40 Swedish crowns (£4 or something) at the most (might even get it for half that price once I find a bloody seller), there's no way I will pay about 120 crowns for shipping, since I can't get it in my town. I was lucky to score that 8 mm rod locally

Maybe that is good that you have 8mm, I didn't like the 6mm rod anyway, it was too weak, bends easily and no saving in material costs whatever. I would say that your situation was a blessing in disguise ha..ha..

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[regpye.com.au]
"Experience is the mother of all knowledge." --Leonardo da Vinci

Bah. I just noticed that the bad-ass motor is 60 mm, not 48. Well, I guess that means I'll have to print some foundation thingy for it to stand on, so the bad-ass one can be recessed 12 mm. C'est la bloody vie, I guess.