Skip to the next paragraph if you don't want the story of my CNC.
Ive been working on a CNC machine for a little over 2 years now and initially i went into this project with a lot of electronics experience thinking it would be easy to build drivers and hard to make that machine itself. Well it ended up being in reverse, the machine went together smoothly sans a sloppy y axis that i have come up with a fix for, and my electronics that i initially made were for unipolar motors (which at the time i thought could be used with bipolar) so they spun a small spare motor as a proof of concept and then were put aside. Next i built a driver based on the reference L297/8 design on a breadboard which did infact work quite well, until i found out that the 2 1/8W resistors i put in it were not enough(someone with jeff in their name recommended i put 2-4W ones in). So another redesign (#3 if your counting) ended up being a properly designed yet bread-boarded combination of PMINMO's design and the reference design, it would work great but would overheat after about 3-5 minutes meaning i should it down cause the L298's were 100C plus. So i built it again but with a big heat spreader and L298's in parallel and holy ____ it worked and it routed the EMC2 logo onto my table (DOH!) and sounded like R2-D2 when it did it. then the breadboard started melting...
And thats where i am now, So basically my question is, what driver board PCB layout should i choose? So far the only board i have heard any significant response about is the PMINMO one, but i'm not sure that all the extra parts are necessary. Is there a significant improvement with them? i.e. What noticeable improvements would it hold as compared to the reference design?
Also i have 2 power supply options a 2.5~3A 28~36V unregulated supply or a 12V 35A regulated supply (pc PSU), Which one would be better (if i were using the pminmo board) and why?
The X and Y are Identical bipolar steppers
----2.5A per Phase
----Insulation Class B
----Made by Minebea
----They just get warm at 12V - no voltage on the label
----1.1 ohm per phase (measured - not labeled)
The Z is also a bipolar stepper that's the same physical size as the other 2
----Insulation Class B
----Made by Superior Electric
----0.95 ohm per phase (measured - not labeled)
Thanks in advance.
Last edited by Micro_CNC; 08-14-2008 at 08:26 PM.