Hey all, I’ve still not made my first cut, I’ve been getting down how to deal with bits physically and all the rest. But I noticed that my machine can sit idle for nearly an hour and if I put my hand on top of the controller it’s hot. The heat sink is hot enough for me to take my hand off in a few seconds. I don’t understand what it’s doing to run so hot, I mean the machine isn’t moving. Is that normal?
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The machine not moving, and the drivers holding the steppers still, is actually what will build up the most heat. 
So that’s normal.
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That’s what I wondered, seems silly. You would think it would just shut them off while idle.
When the machine is going to be idle for long periods of time it is best to power down. As @SLCJedi said the power on and machine idle produces the most heat because all the stepper motors are energized and holding in place. Now if you are going to be a few minutes leave the machine running but if you are going to take a long break or at night power it down.
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Yeah, I usually only leave it for a few minutes. I go back forth from my office to my shop (connected) and do a little something with the machine (learning it), then go back to doing my day job (IT guy working from home). But if it’s more than a few mins I turn it off and unplug it too for good measure (young kids and thunderstorms).
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I have a power monitor attached to my E-stop for my PRO XXL and use an rPi4 with a 7" touchscreen for an HMI.
When the Pro XXL is just sitting, total power used is 42W. About 6W is the rPi4 + screen. The Shapeoko controller probably uses a similar amount. That leaves approx. 30W used to maintain the 4 steppers - so about 7.5W-8/ea. So yeah, it’ll get a heat sink warmed up, but it’s not like the heat dissipation for a high end GPU.
Most power draw I’ve seen yet is during fast diagonal jogs - close to 60W. This all without the load of actually cutting thru material.
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Cool, that’s some useful data, thanks!
I kind of disagree with the above consensus, but only in the sense that it seems that power supply is dissipating more heat than it can remove. High temperature is not good for electronics longevity.
If a power supply gets (generally) too hot to touch then it needs more heatsink or a better fan to remove the internal heat.
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It’s true that high heat will kill electronics. The heat sink on the controller though has to dissipate heat constantly while running a job & would be sized for that.
Thus far from what I’ve seen from just running machine initialization & jogging around while watching power usage, the least amount of power draw is when the machine is at idle. I have yet to watch power usage during actual cutting to see how it compares.
I also have an S3XXL for which the power draw may be quite different as the controller boards are different between the two.
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It is necessary to apply power to maintain position when idle if the machine is not at a full-step position where the magnets would hold at.
When steppers hold position at a micro-step, the drivers are constantly applying power to one electro-magnet, while turning a matching one off, and alternating that power, so as to hold a position at the in-between micro-step position — this results in a heat buildup in those two specific magnets, which is not seen when motion/rotation causes the on/off to be distributed all the way around.
There used to be a laser-cut business-card-sized kit for making a stepper motor, but I can’t find it w/ a quick search.
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Just start cutting! It was made to do that.
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