Monday, 29 March 2010

Pick Your Driver

The most widely available drivers on eBay are based on Toshiba's TB6560 chip. They are advertised at 36V and 3.5A, but you can try that only once - and only briefly. Checking the data sheet for the TB6560 shows that considering motor EMF and safety margins, you don't want to go beyond 30V, or better stay with 24V and 2.5A. I wrote an email to one of the eBay shops about the built-in current reference resistor and it turns out that they are limited to around 2.5A anyway, which is funny given it is advertised at 3.5A. There are similar vibes and concerns on cnczone. Bottom line, at around $73 for 3 axis delivered, they are the best bang for your buck at 24V and 2.5A, but if you want to go higher or want to squeeze better performance out of your steppers, then they're not the right option.

So:  TB6560: 24V, 2.5A, $73 for 3 axis.

One thing to learn from the TB6560 drivers is that you have to treat advertised specifications with a large grain (boulder?) of salt.

Next, there are a range of drivers of varying Voltage/current which all seem to be manufactured by JMC in China. eBay vendors verycnc, yuntat, cnccomponent, and wantaimotor (eBay, web) seem to be the main contenders, and comparing specs, it looks like the drivers offered by Keling Inc (ebay, web) and Zapp Automation (eBay, web) seem to come from JMC too. The Chinese vendors have "entertaining" manuals, whilst Keling and Zapp have the ones you can actually use.

Some offers don't come with a parallel port breakout board (marked "nc" below), which shouldn't really matter as I intend to use an Arduino as a controller, but it would be good to have a breakout board thrown in as a fallback.

Some of the "JMC" drivers don't have micro-stepping, some have too low or too high Voltage specifications, which reduces the possible range of 3-axis drivers to (prices in AUD inc shipping):
  • 75V, 5.2A: $250 nc
  • 60V, 5.6A: $296
  • 60V, 5A: $247, $220, $273
  • 50V, 4.2A: $237 (at auction), $256 nc, $236 nc, $205 nc
  • 50V, 5.6A: $281 nc
Finally, there are the highly regarded GeckoDrive drivers. The best choice for me seems to be the G251.The Gecko Driver has some nice extras, like mid-band resonance damping, recirculation mode, and microstep to full-step morphing. It's not clear if the other drivers offer that as well. Documentation is very professional. So:
  • 50V, 3.5A, $254 nc
I've sent a few questions to vendors and I got some specs to read, then we'll see...

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