Motors

nema 23's are monsters that usually need higher power external drivers than most common 3d printer boards provide, you are more likely to see them in CNC machines than 3d printers. I just got a bunch of these:

http://www.amazon.com/gp/product/B00IEV … &psc=1

they seem to be the ones commonly used in a lot of printers and have pretty decent holding torque numbers. I haven't actually hooked one to the motherboard and tried to make it move yet, but they certainly look OK.

Fun thought of the day: the "14", "17" "23" and "34" in "NEMA 14" etc. refers to the nominal edge length of the square face in 1/10th in: i.e. a nema 17 is about 1.7" (42mm) square. Otherwise they do seem pretty arbitrary numbers haha!

Don't worry about eBay, chinese motors are pretty standard and widely used, and being surprisingly simple machines you're unlikely to have a bad time with them. Make sure you know what you're buying though. A datasheet is always nice, but at the very least note down the torque and current rating of motors you're considering. The current should not exceed the capability of the driver you intend to use (typically 1.5 - 2.0A: check this!). The torque should then be as high as you can get it! >:) Note that in general, higher torque motors tend to be physically longer and draw more current than lower torque motors (which makes sense!).

I could go on, but the choice also depends on what style of mechanism you're intending to run - e.g. ultimaker, core-xy and even delta have no moving motors, so you can put beefy ones in there. For solidoodle cartesian style you'd probably want to save some weight on the moving motor(s). If you're building a giant-format printer, you might have heavy axes and need larger motors. etc. For the extruder, if you're going bowden you might even consider a geared stepper for the extruder to up the res!

That said, if you're sticking to the conventional, then in general NEMA17's are fine, cheap and common.

i'm planing on a tantalus printer which is a cartesian printer i'd like to build something smaller i think the build area is only about 6 X 6 X 6 so i'm thinking i could use the nema 14's with a bowden style print head

since i'm going to do 2 printers i'm thinking i will go with the stock j head printer and the other a e3d lite

Tantillus... According to the reprapwiki page, it's designed for NEMA17s (quite short ones though; <= 40mm). There's your spec.

The drivetrain is basically an ultimaker style, but with fishing line and herringbone gears instead of belts / drivebelts respectively. Cool.

If you've got the room I'd go for the E3D lite on both machines. You probably won't find an equivalently decent j-head for much less.

Well my motors arrived  looks good