3 Axis TB6560 Driver Controller motor sizing

[crazydiamond]

happy new year to all!!!!!

I have recently purchased a 3 axis driver (the generic cheap ebay one) and I am quite happy with it so far (almost a year still running, $78 bucks, can't go wrong). I have been using 78oz-in NEMA 17 motors on my pcb machine, but now finding they are WAAYY to underpowered for my new aluminum beast..

I was looking at upgrading to the 425oz-in NEMA 23 form John at Keling inc. They are rated 4 volts at 2.8 amps per phase but 8.4volts at 1.4 amps when wired in bipolar series.

I understand that the advertised max rated power for my driver is a huge exaggeration at 3amps 36v MAX.. However I cannot understand how the same ebay seller (savebase) is also selling the exact same driver but with NEMA 34 motors rated at 833oz-in at 2 amps included with the kit. how is this possible???? Although it wouldn't be devastating, I've never been to fond of seeing a plume of blue smoke bellowing from my electronics. I just wanted to make sure these motors will work before I go out and but a better driver.

some insight would be greatly appreciated

3 Axis CNC Kit NEMA34 Stepper Motor Driver 833Oz-in NEW - eBay (item 180601516058 end time Jan-14-11 21:39:51 PST)

[James Newton]

First, you're lucky to have gotten as much as you have out of that cheap driver. Most people have serious problems with those (don't take my word for it, search here or on google and see for yourself).

But as to you actual questions, I don't understand what is confusing? The driver is rated at 3 amps, so of course it can run a 2 amp motor. Is it the claim of 833oz-in that is confusing? Very high inductance can provide more torque, but at a cost of lower top speed. You will notice that motor is 12 mH which is very, very high.

I'm not enough of an expert to calculate the top speed you would actually get with that package, but I know from "rule of thumb" (MaxVolts ~= Inductance (in mH) * 32) that to get the motors top rated speed (whatever that is), you would need a 384volt supply, which is ridiculous of course.

The thing that confuses the heck out of me is how on earth he keeps his approval rating at 99.4%

[crazydiamond]

Thank you so much for clearing that up for me James. Certainly answered a lot of my questions. I have dove a little more into slight modifications of the TB6560 driver and I've decided to give some of the "tried and successfully tested" mods a try. If all else fails I'll have to look at a Gecko... This whole cnc endeavor is sure hard on a student budget

Thanks again,

Devin

[James Newton]

Just so you know, that 425oz-in NEMA 23 isn't going to turn all that fast either. 4 volts and 2.8 amps is only 11 watts and that isn't going to push much weight around very fast at all. check out this page to help find what you really need:
http://techref.massmind.org/techref/...htm#Estimating

And THEN find a driver that actually puts that out. You might even find that a Linistepper will do it for you! ;o)

[gabrielmrc]

wrong post