L298N stepper motor driver

So i bought there steppers :http://www.ebay.co.uk/itm/171501140841, as i am building an engraving machine. Until now i had some nema17 0.80 A steppers that were to weak for my need, but the drivers L298N that i had http://eud.dx.com/product/l298n-stepper-motor-driver-controller-board-module-blue-844149662#.VQgQ6o6Udws were up to the task. With my new steppers it's another story, even if i supply the drivers with only 5v they still get very hot in a very short time(under 1 min). I am using the stepper library and if i try to change the speed over 80 the stepper start missing steps, i guess i should increase my supply voltage but i am afraid i will burn the drivers

I had 3 but one burn out when 2 wires going to the stepper touched each other.

I do know that they are not suitable for my new stepper but, until i get my new drivers can i use them without burning them?

Look at stepper motor basics

Those motors require 4.2 amps and a specialized stepper motor driver that can use 12v, 24v or much more to drive them. You need to Google for a stepper driver that can handle (say) 5 amps. Sorry, but they won’t be cheap.

…R

well i am thinking about buying this one :

http://www.ebay.com/itm/3-Axis-LV8727-4A-Stepper-Motor-Driver-Controller-1MHz-CNC-Engraving-Machine-/261745318288?pt=LH_DefaultDomain_0&hash=item3cf13c9990

Until i buy this or another driver the question remains... will i burn the drivers running my new steppers?

Yes, they need 4A and current control, not voltage control (which is what standard H-bridges give).

That is a massive motor, suitable for a hardcore CNC milling machine, way overpowered for engraving I'd have thought. Just how big/heavy is this engraving machine?

thusarix:
well i am thinking about buying this one :

That driver would be just about OK. Personally I would prefer one with a higher current capability in case the salesman is exaggerating.

However as @MarkT says, the motors seem to be overspecced and might perform perfectly well in your project with less than their full current.

…R

MarkT: Just how big/heavy is this engraving machine?

Well it is a small little project that i began as entertainment, but i think i will make it bigger, i will scrap the hole thing and use the x rails and linear ball bearing and use the for the z axis on a bigger machine. But that will be later and this will be may practice model ;D

Here is a photo of what i had, and another one with the new motor mounted without the coupler

Robin2 i guess i will settle for this kit, it is a little more money but i think it is worth it

thusarix: Robin2 i guess i will settle for this kit, it is a little more money but i think it is worth it

That should give you a lot of spare capacity. I note that its minimum voltage is 24v - is that OK ?

...R

Well i guess i should buy a power supply as well, now i am using an old PC power supply.

I read that it is safe to run the motors at up to 20 times the rated voltage. You will actually get better performance by running at a higher voltage than the rated voltage.

Using SMPS powersupply adapter may work? I have been dealing with same problem. I changed the driver but I am hoping to find an answer to using SMPS powersupply may or maynot help the issue.

thusarix: Here is a photo of what i had, and another one with the new motor mounted without the coupler

Run that without a proper mounting frame and that motor will probably twist up those bolts nicely!! I don't think you need anything like that amount of torque - with an M10 leadscrew it wil generate about 20kN of linear force (2 tonnes), that's way beyond what the frame can stand. (OK, at speed the torque will be a lot less, but still)

Robin2 i guess i will settle for this kit, it is a little more money but i think it is worth it

NEMA17 motor and a DRV8825 driver board would be much cheaper...

MarkT:
NEMA17 motor and a DRV8825 driver board would be much cheaper…

+5

…R

MarkT: NEMA17 motor and a DRV8825 driver board would be much cheaper...

At 5V the NEMA 17 steppers that i had were not giving the torque that i wanted, at 12V the steppers were performing well but the drivers were extremely hot, very fast. I could not touch them after 2 min of runtime. Frustrated i said, "there steppers are trash , and the drivers as well......i will buy something that will not give me problems, power wise". So i ended up buying there motors. Anyway the deed is done, so i might as well use my powerful new steppers.

All the one-chip stepper drivers get very hot, they have DMOS integrated MOSFETs which more than an order of magnitude below the state of the art for discrete MOSFETs which have vertical current flow.

Recently I've been experimenting with the DRV8711 chopper driver which uses external MOSFETs and so isn't limited to 1.5A or so at all. Very nice performer, it would be great to see a driver based on this available commercially (TI do do a little evaluation board in fact, but you have to talk to it with SPI at reset to set it up).

If i would have asked my question prior to buying the new steppers you would have recommended me something like a set of drv8825 driver bords? And they would have provided with the necessary regulated power to drive the NEMA17 steppers at optimal capacity?

And this clears things up about the L298N

MarkT can you tell me is a 10A power supply will be enough to power my 3 nema23 4,2A stepper?

Running with DRV8825's at 36V and proper thermal management you'd be able to get good performance (lots of torque upto 1000rpm I would expect).

My personal best with a 1.2 ohm 2.5A NEMA17 is 3750rpm (rather flaky, no torque left!), but decent amounts of torque at more plausible speeds. That was only a 20V supply.

I put a fan on top of the L298 radiator and it keeps it cool enough for me to operate the big motor at 5V.