GShield Temperature and Themal Shutdown

Well temp is not an issue. :smile:
Not even when driving dual Nema 23 stepper motors.

In order to stop some slipping issues I was having I kept increasing the current to the Y axis steppers.
However, I was concerned about the chip overheating and causing thermal shutdown errors.

So I got out the probe thermometer and taped the sensor to the chip while I ran a couple of carves.
According to the spec sheet I found online the chip should have a max operating temp of 150 C
With the pot turned up to max (any higher and the steppers start to vibrate and do weirdness) and the chip never got above 22.7 C.

When I took the sensor off I put my finger on the chip, just in case the meter was not reading correctly. Sure enough the chip was only slightly warm.
Yay active cooling!

So as long as the cooling fan is on I don’t think overheat will be an issue with the GShield.

Aron, I’m glad you posted this. I wanted to make a similar post today regarding some testing I have done with my gshield (x-carve not here yet but I have electronics!). Running the easel test program with the motors hooked up but not pushing a load I see temps around 90F (~32C). I was also just running the gshield sitting against the powersupply fan for cooling. I’m looking into a permanent cooling solution for my custom electronics case and wondering how far I need to go with it.

What are other people’s experience with gshield? Are you experiencing thermal cutoff with the stock Inventables cooling solution? Do I need to invest the time and money into something more elaborate such as heat sinks or is a 24v fan blowing on the shield sufficient during actual loaded use?

I guess I misunderstood the problem, I thought that the issue with upping the voltage was that the motors would overheat, but it’s the driver chip that we need to worry about?

It’s really hard to imagine that tiny 24 v shield overheating Nema 23s. I’m 99% sure you would see smoking chips before damaged motors. The bittersweet smell of ozone… aaaaahhh.

1 Like

Overheat issues are with the driver chip not the motor.
The driver chips have automatic thermal overload protection. So if they get too hot they shut down rather than fry.
If you are running your chips hot it can start shutting down causing it to miss steps.
At the lower edge of overheat it can shut down for just a few pulses at a time, causing this weird stutter pause effect.

I don’t have the specs handy but the max operating temp of the stepper is something like 80c, so they would become dangerously hot to the touch long before they would reach their max operating temp.
You can touch your steppers and get a feel for how things are tuned.

(When I was tuning my 3d printer I got a dual temperature probe meter and put a probe on the stepper and the driver chip.)

@AaronMatthews

With the pot turned up to max (any higher and the steppers start to vibrate and do weirdness)

Huh?

chip never got above 22.7 C

I think there’s something wrong with your test. I have a better feel for Fahrenheit, 22.7 C is 72.86 Fahrenheit. Body temp is 98.6 F. 72 F degrees shouldn’t feel warm to the touch.

Yay active cooling

What type of active cooling are you using?

1 Like

“The steppers started to vibrated and do weirdness”
Yeah I am not sure what that was about. I vaguely remember reading about too much current causing problems in the steppers.
I was adjusting the current while running a crave. As I turned up the pot the steppers started to shudder and vibrate. I am not sure what was going on. I figured “too much!” and backed off a bit.
It seemed to work

“chip never got above 22.7 C”
That is what my probe thermometer read and it is surprisingly accurate. I originally bought it to run some temperature tests on my 3D print head.
By “Warm to the touch” I meant it was warmer than the cold metal of the case or the surrounding circuit board. Barely noticeable, but detectable.

“Active cooling”
Active cooling just means using a fan, as opposed to passive cooling which is just letting the chip sit there, possibly with a heat sink.
In this case the fan that comes with the controller, which seems to be very effective.
My 3D printer has no cooling fan on its electronics so heat build up is more of an issue. Relying on the passive cooling of the heat sink build into the circuit board.

Here’s an IR image of the g-shield while it’s running. I’m getting temperatures around 200F. Data sheet for the stepper motor drivers state a thermal shutoff of 175°C (~350°F)

Datasheet: http://www.ti.com/lit/ds/symlink/drv8816.pdf

1 Like

Obviously, from the image you don’t have the fan on the unit. Do you have a fan blowing across the gShield while you are measuring the temps?

1 Like

I do now. I have the pots turned to a little under 12:00. Im getting temps about 60-70°F less.