Cobra Stepper motor drivers

[Jason Marsha]

Anyone using Cobra Stepper motor drivers?

I saw some 2550 oz/inch nema 34 motors at homeshopcnc rated at 8 amps, can these stepper drivers push these babies to max potential?

Jason

[ger21]

Jason, what do you plan on doing with those motors?

[Jason Marsha]

I am planning to use them on my belt driven 5x10 router.

They may be overkill but the gantry seems to be turning out heavier than I expected. The gantry will be possibly constructed from 150mm x 80mm hollow section with a 6mm sidewall (I think), so its really heavy. I am estimating gantry weight to be at least 200 lbs with all accessories.

So driving the long axis from both sides I am assuming that quick changes in direction will require some really beefy motors. The long belts will be 25-32mm wide belts with a 6.25 to 1 reduction.

Jason

[ger21]

Just a guess, but I think that's far more power than you need. 200lbs isn't that much weight.

[Jason Marsha]

About what size would you think is suitable.

I also noticed that all of these new RS motors from homeshopcnc need lots of amps, even the weaker ones.
The 1840 oz/inch and the 1290 oz/inch models also need 8 amps in parallel mode.

http://www.homeshopcnc.com/page6.html

Jason

[ger21]

Higher current motors are better for higher speeds. I'd rather not give a suggestion, as it would just be a guess. How fast are you looking to go? Do they have any torque curves available for those motors?

From what I've read, large motors typically don't run as smoothly as smaller motors. Fwiw, I've sen a few machines here using 400 oz motors with 2 turns/inch screws able to rapid at 300-400ipm, with gantrys that probably weight over 100 lbs, maybe more. Check out routers by Hack (Data-Cut plans) and Inventit.

[Jason Marsha]

I was thinking about 600ipm rapids and cutting at about 400 ipm.
I am not sure if the belts can handle these numbers.

I will check and see if Benny posted any speeds with his belt drive table.

Jason

[routerman]

I saw some 2550 oz/inch nema 34 motors at homeshopcnc rated at 8 amps, can these stepper drivers push these babies to max potential?

Yes, the Cobra can run up to 10 amps/phase and can take the heat. Ive used them on a bridgeport mill retrofit where they ran at 9 amps, no problem. I was running a 65volt powersupply. They ran very smooth too.

[Jason Marsha]

Thanks Routerman.

Jason

[Kelinginc]

Pls check here for stepper motor info
http://www.kelinginc.net/SMotorstock.html

[springlakecnc]

For steppers, why not look at keling? you can get the motor AND the drive from the same place, and they can help match the package for you.

I built many cnc machines, and when using components that come from differn't places, if something don't work right, the drive manufacture simply point their finger at the stepper/servo motor manufacture, and the stepper/servo motor company points their finger at the drive manufacture. No one takes the blame. If you get them from the same place, you have that potential problem solved. I believe you can get the power supply from Keling also, now you have that matched with everything also.

I installed some Kelings and liked them.

Good Luck,
Buck

[Jason Marsha]

Originally Posted by springlakecnc For steppers, why not look at keling? you can get the motor AND the drive from the same place, and they can help match the package for you. I built many cnc machines, and when using components that come from differn't places, if something don't work right, the drive manufacture simply point their finger at the stepper/servo motor manufacture, and the stepper/servo motor company points their finger at the drive manufacture. No one takes the blame. If you get them from the same place, you have that potential problem solved. I believe you can get the power supply from Keling also, now you have that matched with everything also. I installed some Kelings and liked them. Good Luck, Buck

Above 8 amps keling does not have a drive to push the motors, the largest I saw was 7.8 amps.

Jason