The DIY CNC team got heavy into learning stepper motor and driver
issues last Tuesday night. The following are some links that provide
further background on the topic for those that are interested:
We're looking for the most cost-effective, easy-to-deploy, and
reliable solution for a typical NEMA 17 stepper/driver combination
right now; before we scale-up to bigger pairings on next projects.
We're just trying to keep the magic smoke inside the motors and
I have been doing a lot of research on this, and almost have a completed schematic involving up to eighth step microstepping with 2A of current, for a fairly reasonable price - the chip is about 5 dollars in single amounts, and the rest of the components are less than another 5-7 dollars, or a little more depending on what sort of connectors we want. I can meet with people before the meeting on Tuesday about it, or simply present what I have then.
My Senior Design project for UC also involves designing and building a CNC router. I am sure my group would be willing to chip in to buy some of the drivers, especially if we will be able to get some kind of bulk discount.
That sounds great. Also, I misspoke before - the driver I am looking at is capable of 1/16th step increments. I did a thorough investigation of the ones we're using in the RepRap/MakerBot, and although they are ready made and cheap, they are also only a maximum of 1/2 step precision. If this doesn't matter, we can use those, otherwise we should roll our own. In fact, I believe I can design a board that is fully compatible with the inputs/outputs of that board - we could even offer that to sell, to give people greater precision of movement in their MakerBot designs.
I'm looking at the Allegro A3979 chip - http://www.allegromicro.com/en/Products/Part_Numbers/3979/index.asp - which can go up to 2.5A. Most of the other chips can only do 1.5A, which really isn't enough to push our 2A steppers. Other individuals have created circuits based around this chip as well, so it should be simple to implement.