Need advice on motors for Kossel build

Hello!

I'm about to buy motors. I have a RAMPS 1.4 with A4988. My research says:

Nema 17
1 amp-2 amps
60-80 oz hold torque.

Not sure about shaft length.

I'm on a budget and found these motors on ebay. My budget is about $10 a motor. Can anyone with experience let me know if these are powerful enough for my project?

I'm also concerned voltage and amps will be acceptable with my 12volt power supply and a4988s.

really appreciate it.

Here are the links:

5 X Nema 17 Sanyo Denki Stepper Motors

[www.ebay.com]

Stepper motors NEMA 17-DIY CNC ROUTER MILL ROBOT REPRAP

[www.ebay.com]

5 Nema 17 Japan Servo Stepper Motors 51.2oz/in

[www.ebay.com]

A bit more expensive (Is it worth it?)

5pcs NEMA17 BIPOLAR STEPPER MOTOR 76 oz-in


[www.ebay.com]

Those motors all look a bit under-powered, but may work just fine for a Kossel. I would be a bit worried about using one for the extruder though. Generally you want motors that are less than 3Ohm and rated for 2+ amps. This usually means motors that are rated for 6V or less (our stepper motor drivers limit current, so we can safely run them off of 12V). Running a motor rated at 1 amp at full current will cause it to get quite hot (though still technically within normal operating temperature).

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Thanks.

So I need to look at less than 3 Ohm and 2 amps and under 6Volts. Isn't the holding torque the important thing?

So many variables to take into account. What is an example of an affordable (cheap) motor with proper specs for a RAMPS 1.4 w a4988?

I've built two printers so far with the motors in the first link and they work fine even in an extruder. The only catch is that the shafts are 4mm, so you'll need to make sure your pulleys and extruder gears take that into account.

I'm looking at these motors now. Tell me wht you think:

Remember I will be using RAMPS 1.4 and A4988, with heat sink, and I will add a fan.

42BYGHW811

Holding Torque:4800g-cm(70 oz-in) Type:Hybrid Brand Name:Wantai Motor Phase:2 Current / Phase:2.5A Certification:CE,ISO,ROHS Step Angle(degrees):1.8degree


1, Technical Specifications

Part No.: 42BYGHW811

Frame Size: NEMA17

Step Angle: 1.8 degree

Voltage: 3.1V

Current: 2.5 A/phase

Resistance: 1.25 Ohm/phase

Inductance: 1.8 mH/phase

Holding torque: 4800g-cm 70OZ-IN

Rotor inertia: 68 g-cm2

Detent torque: 0.28 kg-cm

Number of wire leads: 4

Weight: 0.34 kg

Length: 48mm

Those look perfect.

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Thanks for your help. I'll order them. :-)