Re: Which stepper driver card to buy??

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "squidsrus85"
<squidsrus85@...> wrote:

>
> Hi people,
>
> Probably a tough question, but I have just added 3 x 150oz/in steppers
> to my Sherline mill and now need a driver card.
>
> The motors are 2.26v and 4.6A.
>
> I'd like to use a driver with 5A but have not found anything at a cost
> I can afford. Any suggestions on that?
>
> Next idea is to connect the motor in series for 2.3A and that opens up
> a bunch of drivers.
>
> Can anyone please recommend any particular boards from experience in
> either the 5A or 2-3A ranges.
>
> I did a search here and found mention of a camtronics 5A board but
> cannot find it listed on their website., It looks to me they have gone
> with Gecko drives instead. I cannot afford 3 of those as much as I
> might like to.
>
> Oh, I will be using Mach3 on the PC. Have not bought it yet but next
> in line after the driver and power supply.
>
> Thanks for any help.
>
> Dave
>

WOW! 4A for 150oz-in motors??? Must be older motors. If they are
eight wire you can run in series. You lose some lower end torque but
at half the current you find your choices for motor drivers to be
better suited to you budget.

There are bipolar and unipolar. THe important thing is that they are
"chopper" drives (No big external current limit resistors) and they
are microstepping.

For assembled and tested bipolar your best bet in the sub-3A range is
the Xylotex. Of course I am biased since I use them in some of my
built and tested 4 axis controller box and we have good results and
few failures.

Hobby CNC sells a unipolar microstepping chopper drive but I think
it's a build it yourself kit (?)

So what is the difference between the two? The bipolar has a edge in
performance because the drive current switches polarity and uses the
whole winding. It "sweeps" the current that naturally gets stored in
the motor inductance out faster so you tend to be able to get a little
more speed and performance over unipolar. Unipolar drives need motors
that have a center tap in each winding so

Just an FYI some of the newer hybrid motors are rated at 260 oz-in and
less than 3A. 4 wire motors so they have to be used bipolar. There
are even 400 and 500 oz-in steppers that draw about 3A.

The camtronics 5A stepper is dead and gone. Dan Mauch swtiched over
to Geckos a couple of years ago.


Tom Caudle
www.CandCNC.com