I use a modified version of CNC3AX created by Laurent Fouga
She is a board of low cost, supports 3 "steep motor unipolar to 5A - 80V
There are many colleagues in another forum I attend, using the modified CNC3AX very successfully.
The original FETs, were replaced by IRF640, with 12V power
Electrolytic capacitors have been changed to 100V

I am very pleased with it.

Double-sided version (original) PCB
http://mac1.ifrance.com/cnc3ax/pcb_s.PDF
http://mac1.ifrance.com/cnc3ax/pcb_c.PDF

Parts List
http://mac1.ifrance.com/cnc3ax/lisezmoi.txt

face - simple
http://www.guiacnc.com.br/index.php?action=dlattach;topic=67.0;attach=336

Tests
http://www.4shared.com/document/B3iKvfVp/Diagnstico_CNC3AX.html

scheme
http://go2.wordpress.com/?id=725X1342&site=areacnc.wordpress.com&url=http%3A%2F%2Fareacnc.files.wordpress.com%2F2009%2F05%2Fcnc3ax_sch.pdf&sref=http%3A%2F%2Fareacnc.wordpress.com%2F2009%2F05%2F14%2Fesquema-da-placa-cnc3ax%2F

other links:
http://search.4shared.com/q/1/cnc3ax

Vídeos:


Hugs

 

The only problem that I have with it is that it is unipolar. Your stepper can give more power if it is connected in bipolar. There are many boards for unipolar but I personally never considered them just because of this limitation.

 

marcomartim, thanks for the info. I will definitely check that out. I have been looking at various diy designs lately.

@TigerPilot,
I used to think that way about unipolar, but it's not 50% less torque. It supposedly gives 70% of bipolar. Also, 5A is double the current of the stock phlatprinter board, so that's actually a more powerful board. I personally would seriously consider using unipolar, and even contemplate getting one of the hobby cnc kits to try out and also practice soldering up a board.

-Kwok

 

Indeed, in the unipolar drive there is a loss of torque, but has a higher rotation. With a higher voltage, the loss of torque is not very significant.

If you have engines 5,6,8 wires, can call in unipolar or bipolar

Hugs

 

I had a router, X axis = 950mm, Y = 750mm, Z = 90mm. 3 engine with steep 15kgf.cm
I used it to CNC3AX changed (since this machine was sold).

I'm building a table for (the plasma cutting) X 3000mm Y = 1650mm Z = 150mm.
I'm with CNC3AX assembled and test very successfully engines 15kgf.cm = 208 ozf.in (Z axis), 32kgf.cm = 445 ozf.in (Y axis) and 42kgf.cm = 583 ozf.in (X axis)

On that machine I intend to use Sketchup + Phlatscript. When you have more progress, I comment here.

Hugs

 

I spit the discussion of Unipolar vs Bipolar to another thread: viewtopic.php?f=127&t=2236 We can talk specifically about the CNC3AX driver board here.

-Kwok