Thursday, 11 February 2010

New toys - baby steppers!

Kickstarting my RepRap project again, I splashed out on four NEMA 17 stepper motors from Zapp Automation - four SY42STH47-1684B motors. Good service, arrived quickly and well packed.

I needed a stepper for an extruder, so I got 4 to give an easy upgrade path to a mendel.

I'm currently running on generation 2 electronics, so I also need another stepper driver. The gen3 boards are great, but they are out of stock at the moment, and because they're fully populated, they would replace my current setup - not a problem, but an expensive upgrade.

While looking around, I found a couple of other posts on this subject:

Casainho also grabbed one of these motors
and is looking at driving it with a Pololu Stepper driver board.

Bothacker posted about his electronics setup which uses Sparkfun driver boardscontrolled by a Seeduino Mega.

I really like BotHacker's approach. It's modular, so it's easier to upgrade and slightly more flexible for re-use on other projects, and the seeduino/arduino split for extruder heads can be skipped to start with (as most only have one working extruder) and added later if required. It woul probably be more expensive overall, but is probably more readily available - the driver boards are replacable by other manufacturers, other mega/seeduino controllers can be plugged in. The connector boards are easier to design and manufacture at home, reducing the bottleneck of available boards.

I'm currently leaning towards BotHacker's approach.


Casainho said...

Hello :-)

Pololu stepper driver looks to have more steps and handle more current! so, maybe better for extruder, which may needs many steps for precision.

But I Pololu ones are far from good because they need heat dissipation, which is hard to do and since that board is not ready mad for that :-( -- I would say that Pololu boards are faulty because of that!

As you know, with that drivers you will not be able to take the full power of that motors, because you hust can get max of 750mA from driver.

Please report later about the temperature of that drivers at full current...


Casainho said...

And I am already using that stepper motor and driver, see here the pictures :-)

BodgeIt said...

The stepper Im using to get 4.7kg of pull is set for 500ma the specified/sugested ;) current is only 400ma.

So the Easy step boothacker solution is quite capable for A "no comparmize extruder" worm geared extruder setup.

Im not sure if the Torque gain is directly proportional to the gear ratio mine is 26:1 Nopheads is 40:1. The extrusion resolution gain is easily calculated from this ratio.