Stepper motor drivers

I am working on an arduino project and I need to control seven stepper motors that each require more than the three amp output of my Adafruit motor shields. I need to keep this to one board to keep it from becoming too complicated. Is there anything out there I can buy to amplify the output and control the motors with that is a stackable shield?

Stepper motor: http://www.robotshop.com/en/12v-17a-667oz-in-nema-17-bipolar-stepper-motor.html#Specifications

that each require more than the three amp output…

Those motors are 1.7A each.

Are you intending to drive them all together from one driver, or are you looking for 7 drivers on one board?

I know they say 1.7 but they wont work on that low current. I am hoping I can use some that will run two motors per driver.

You can run multiple motors per driver if you wire all the A windings in series and all the B windings
in series. You don't use motor shield for this, you require a chopper driver which can handle 1.7A,
such as DRV8825 (it'll run very hot but should cope with suitable cooling).

Low impedance steppers like this are current driven, which is why you need a chopper driver and
why you wire them in series not parallel.

You would probably do best to drive each individually with a DRV8825 breakout board, they are
plentiful and quite cheap on eBay these days. Wiring motors in series will reduce top speed as
the available voltage per motor is reduced - the voltage has to be able to overcome back EMF which
increases with speed.

And yes they are 1.7A and you should not exceed that or they will burn out and demagnetize.

Steppers are not like other motors, don't make the mistake of assuming that.

I realize that they are 1.7 amp rated. But it wont work with the adafruit motor shield I have. I dont want a breakout board. I need a stackable shield. Thanks for the recommendation.

No it won't work with the motor shield because its a low impedance stepper that requires
current drive, not voltage drive. I've said this already. You'll have to find a stackable shield
with chopper-driver chips on. Simple H-bridges will not drive this kind of motor from 12V
without burning out and/or damaging the motor.