UPS and Spindle

I’ve ordered SO5 and VFD. I’m planning to use UPS for the machine and am thinking about a 1500VA true sine wave type. But realize that this UPS will not be adequate for the spindle. Right?

If so, how do you deal with short power outages and not lose work?
Especially if power flickers?

Even if you come up with something for the spindle, what about dust control (shop vac)? Also are black/brown-out/power flickers common where you live? You definitely don’t want the axes trying to move if the spindle goes off.

FWIW, at work we have a large CNC machine with no back up power. While not common, we have had power outages (both brief & long) that have interrupted work. Depending on the operation, sometime I just restart at the beginning of the toolpath that it was running when the power went out. Other times, I’ll edit the g-code (by hand) or do a quick re-program of the toolpath (in our CAM software) to pick up shortly before where the machine was when the power went out.

And on this particular machine a noticeable flicker will usually cause a fault (usually in either an axis or spindle or both) resulting in the machine stopping and an alarm sounding. However I have seen really fast/brief flickers not cause an issue.

Possibly the “safest” solution is if you are in an area where solar power is worth doing and putting the circuits that the machine, spindle, and dust control are on on the battery side of the solar system. However this really is only (in my mind) “feasible” if you are already looking at putting in solar or already have solar. Definitely not an inexpensive solution (nor likely feasible for most people) for just making sure your machine is not affected by power surge/brown-out conditions (particularly if they are not a regular issue).


Thanks a lot. That’s giving me peace of mind!
Power outages happen from time to time in my area.

So it looks like the PC is the only thing that needs an UPS. Good.
I knew about solar power, but not about such solutions: slight_smile:

Also. VFD draws 12 A. Is that a start or constant usage?

I got an HF dust collector, which I think uses 20 A.
It’s probably worth it to have outlets on two or more independent circuits. Right?

Get a bicycle and hook it into the system for outage events.

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Well, it’s a clever solution. But I’m running my bike regularly anyway so run it for a CNC as well can be a little bit too much :slight_smile:

A UPS is not a bad idea. But it would be prudent to have the machine, spindle, and computer on it. Although if you’re using a tablet or laptop, it has a battery and can be left off the UPS. If you just have the machine, then the machine will try to push on while the spindle shuts off, and vise-versa. Depending on the length of the power outages you can just pause the machine. But on the SO5, the spindle keeps running. I’ll have to go home, pause the machine, and hit the red-ringed button on my VFD to see if you can stop the spindle while the machine is paused, then turn it back on and resume…in order to save some battery.

But it depends on how long your power goes out I guess. You may be able to just keep running if it is only a few minutes.

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Cost can be an issue but why not two UPS’s. I thought they wanted the C3D Spindle to be on its own power source anyway.

I live out in the country and the grid I am on is always the last one to come on. I can tell that the power went off if I am gone by my stove clock blinking. Luckily it has several months since I came home to find the clock blinking. I have had he power flicker off during a rain storm but it happens so infrequently I have not bought a UPS. If you live somewhere where the power goes off regularly the UPS might be a solution but if you have relatively steady power the expense would have to be calculated for return on investment.

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Thanks! The points you provided made this more clear to me.
I’m just afraid of the possibility of losing the electronics or damaging the machine when the power is unstable.

I’m trying to prepare as much as I can while waiting for my first CNC :slight_smile:

The machine itself is not likely to suffer any failures due to a power outage…projects on the other hand may get ruined.


A surge (or power spike) is what will damage electronics. I would simply plug the machine & computer into a surge suppressor power strip (or even a single outlet surge suppressor if on different outlets).

A power outage will just cause you to be in some limbo state in the middle of the project, which depending on your skills may result in a ruined project, but not if you are careful (on picking where in the project to “restart”).


Thanks Mike. Surge protection definitely make sense.

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