Steppers and obtaining them

RepRap currently uses two stepper types:

1. Nanotec ST5709S1208-B (http://www.nanotec.com/page_product__st5709__en.html)
2. Keling KL23H51-24-08B (http://www.kelinginc.net/NEMA23Motor.html)

and there's also

3. Lin Engineering 5718X-05S (http://www.linengineering.com//site/products/5718.html)

which we haven't tried, but does have the right spec. 1. is spot on technically, but expensive and hard to obtain. 2. definitely works with the Arduino controller, but has yet to be proven with the PIC. 3. should be OK, but (like 1.) is a bit pricey.

What we need is a NEMA 23 bipolar motor with coil resistances of about 10 ohms that'll take an amp, and that doesn't cost the earth.

Any suggestions?

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best wishes

Adrian

[reprap.org]
[reprapltd.com]

Looking for 10R motors restricts the choice and performance. Better to fit the electronics to the motor rather than the other way round because the motor costs more. Modern motors are low inductance, low voltage high current. Zach has shown that simply by adding the cost of an L297 you can use a more common and hence much cheaper motor, easily saving the price of the L297. Bipolar chopper drive also lets you use virtually any NEMA23 motor 12V or less, allowing locally available motors to be used.

A mechanical change to not require the second shaft would also widen the pool of suitable motors.

A firmware change to the PIC that allowed each step to consist of a 100% power pulse followed by PWM, both configurable, would allow it to emulate a chopper in software. Given the motor inductance, resistance and current spec, the on time and PWM could be calculated. Being open loop it would not be quite as good as a chopper but not far off I think.

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[www.hydraraptor.blogspot.com]

I've hacked the Z motor bracket to use a single shaft motor. It basically lets you mount the Z motor the other way round.

Unfortunately the Lin Engineering 2.5A steppers I have have got a 1R coil resistance, so I can't drive them from PIC boards. So if I'm to stick with PICs I'll need different motors, or a different driver design.

Vik :v)

You might be able to drive them from the PIC if the PWM is fast enough, compared to the inductive time constant, to not let the current exceed the L298's max.

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[www.hydraraptor.blogspot.com]

we should choose controllers according to motors we have not the other way around coz contollers are a lot cheaper than motors. also how about salvaging motors from old cd-players, floppy drives, inkjet printers and any other old electronics one could get for free or nearly so

i wouldnt be too sure about that r2k. your average stepper motor suitable for a RepRap machine costs up to $30. the one we spec'ed out from Keling is $25.

a commercial stepper driver will set you back at least $60, but more like $100. hell, even the stepper driver we provide still costs at least $30 in parts.

its much easier to standardize on a controller, then find motors that are suited for it. if you build your controller right, it will be suitable for a wide variety of motors (like our current one is.)

These days CD drives, printers and so forth use DC servos, not steppers so they're not good sources of either steppers or drivers.

'Course, someday we might have a DC servo driver...

Vik :v)

On the DC Servo Driver. Admittedly progress has slowed somewhat but has definitely not stopped.

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

There is also the very cheap, Darwin-friendly, energy efficient stepper from CW-motor

[blog.reprap.org]