Higher Amperage Controller

So, a friend of mine and I are a bit new to reprap, although we've done a lot of research and experimentation. Yet, we still don't have stepper motor control 100% figured out. RAMPS are great, but they limit the current to around 1 amp. Higher may be possible but I don't trust it not to overheat.

So, what if I want 2 amps or 3 amps for a more industrial, commercial or more power hungry application? What would you use? I want to keep the cost low, if possible of course. So, what are my alternatives that are reliable? We've seen a ton of controllers on ebay that say they can do 3.5A, but since they are Chinese, I suspect they are crap and break easily. It's amazing to me how hard it is to totally figure out stepper motor control.

Any suggestions?

from an electronics point of view, the stepper coils are driven by the mosfet, so if 1 were to directly dig in to improve output, change the driver portion with an alternate mosfet. thats the theory at least in my mind, however, ramp being a SMD board, it will be really challenging to do that, unless u use an alternate board that allows some space on the pcb for mods?

redreprap Wrote:
-------------------------------------------------------
> from an electronics point of view, the stepper
> coils are driven by the mosfet, so if 1 were to
> directly dig in to improve output, change the
> driver portion with an alternate mosfet. thats the
> theory at least in my mind, however, ramp being a
> SMD board, it will be really challenging to do
> that, unless u use an alternate board that allows
> some space on the pcb for mods?


Unfortunately, this is not possible. RAMPS uses the pololu style drivers, which feature a monolithic stepper driver--that is it has the mosfets built-in.

If you want to drive 3.5A stepper motors, I suggest you look into Gen7T instead of RAMPS.

... I've simply wired the 'logical' pins for CLOCK and DIR of the Pololu-sockets (and the endstop-pins) to the corresponding pins in my Isel-CNC-controller - the drivers of the controller are happy with 70Volts@6Amps, no problem to use other types too ...

---

Viktor
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As for Gen7T it's not really working fully right now and is kind of on hold. AKA47 did some gen3 style modular driver boards you could hook up to an arduino or something. Just google AKA47 and stepper and you should be able to find it. Also there is phoenix electronics which are also modular and look to be well tested.

[reprap.org]

And of course if you want to wait there should be quite a few more after the contest.

[reprap.org]

Be advised that although the TB6560 says it can handle 3.5 amps and 40V or so those are ABSOLUTE max ratings and even brief excursions beyond those values can kill the chip. My reccomendation would be to consider 2.5 A and 30V as the working max values for this chip. Amps could possibly be bumped up a bit with serious active cooling but voltage spikes seem to be a major failure path for these chips so I would be very conservative with voltage if I were you.

ah yes you are right, i forgot that polulu are single chip solutions with mosfet inside.

Annirak Wrote:
-------------------------------------------------------
> redreprap Wrote:
> --------------------------------------------------
> -----
> > from an electronics point of view, the stepper
> > coils are driven by the mosfet, so if 1 were to
> > directly dig in to improve output, change the
> > driver portion with an alternate mosfet. thats
> the
> > theory at least in my mind, however, ramp being
> a
> > SMD board, it will be really challenging to do
> > that, unless u use an alternate board that
> allows
> > some space on the pcb for mods?
>
>
> Unfortunately, this is not possible. RAMPS uses
> the pololu style drivers, which feature a
> monolithic stepper driver--that is it has the
> mosfets built-in.
>
> If you want to drive 3.5A stepper motors, I
> suggest you look into Gen7T instead of RAMPS.

I think you can get cheap OR reliable. The TB6560 based driver are cheap but don't have a great reputation. They often seem to be current limited to 1.5A or so anyway. The M542 drives have a good rep but aren't cheap.

Recently I got a cheap Chinese CNC machine, I have tried controlling it from a printer controller with the STEP, DIR outputs wired to the DB25 connector on the control box (which contains TB6560 drives), seems to work OK.

I found a great alternative to RAMPs stepper motor control today! It can handle 2.5 Amps per motor, 3rd order acceleration planning, and still $32 or less per motor! RAMPs is about $27 per motor at retail pricing.
Synthetos 3 Stepper Motor Controller Shield (grblShield v4)
TinyG 4 Stepper Motor Controller with Built-in Microcontroller ($129)


3rd order S-cuve acceleration planning Means you can drive the motor harder without it missing steps. Supposedly it also drives the motors more smoothly than other boards. Awesome stuff! I'm very excited about this!

What do you guys think? Anyone have experience with this controller and have any other views on it?

Edited 5 time(s). Last edit at 12/20/2012 09:16AM by daveycrocket.