Hi,I wrote "1.2A/coil" which indeed should be peak and as there are always two coils, the result is 2.4A (max).If you go for 270oz that means in metric values 1.9Nm which should be more than sufficient for your CNC (provided for that the linear motion system is quite good).I wonder where you would get those motors for 10-15 bucks/piece. The cheapest I found was $22.Nevertheless, if you really want to do everything right from the beginning, then you should first build all the mechanics together, adjust and fine tune as much, precise bevels etc.Then you can measure the friction exactly and calculate how strong your steppers have to be when they have to drive the router through your work pieces at a desired speed.But theory is one thing, reality another one.If you get those steppers, they should do. And then you have to decide for the drivers and power supply.Normally I wouldn't add all current consumptions of each single stepper. They don't work too long all together, one or two are busy, the third one idle.So you might get along with the addition of all 3 stepper currents minus 20-25%, to have a little bit extra, when all 3 steppers should be under full load at the same time.
So go with a bigger one.My recommendation nowadays is a TB-6600 or ST-6600 based driver.I found some by asking Google "ST-6600 stepper driver" - price in Europe: 22€.There are still TB-6560 out, but looking at the datasheet of the 6600, this is a better choice.The newest ST-7128 are out now, but I can't see the advantage which I could make use of compared with my 6600 based drivers.
I've checked it, the motors rated voltage is 3A....Either way, the DRV8225 is not powerful enough for these motors.
I read so many negative things about the 'tb' drivers at cnczone.com over the last several years
Do you mean, Mark, that I should use belts instead of ballscrews?
If I'm not mistaken, you're using belts for the X and Y axes while the Z axis is driven by a ballscrew.
I've found an equation for ballscrews (I've been searching for these equations, but Google wasn't willing
I never mentioned ballscrews (expensive), and if you read my posting again it is quite clearthat I mention belt drive only for laser cutters where the forces are much less.
Thanks, billcat, I'd appreciate it