Interesting, but does it cover what to do when you’re 40 minutes into a 3 hour CNC program and the b@*&dy power disappears for a few seconds and everything shuts down, like wot happened this evening?

 

That’s the third power cut we’ve had here in the last two weeks, mumble, mumble, mumble. Every time it rains the power seems to go off. And to add insult to injury E.on have just announced stonking price hikes.

In the end I did what any seasoned machinist would do; I went to the fridge and grabbed a beer.

 

Regards,

 

Andrew

 

Hmmm, I wonder if this off-topic post will get me ex-communicated?

 

 

The power here was only off for an instant, enough to badger the CNC mill and the clock on the cooker, but not the clock on the microwave. I suspect all three phases went, as the CNC mill and the computer that runs it are on different phases and they both went off, and I think the house is on the other phase.

 

The time before when the power went off it was out for an hour, came back for 15 minutes and was then out for two hours. We have overhead and underground cables in my steet. I get my feed from the underground cable, but I’m pretty sure the ultimate feeds are overhead on telegraph poles. I live in the country, but I’m hardly in the sticks!

 

At least I don’t think it’s damaged anything, just that I’ve lost the zero references for the part I was machining. The XYZ references I can get back, but the 4th axis (A) may be a bit more difficult. I’ll give it a go tomorrow morning, otherwise it’s bin it and start afresh with a new cast iron blank.

 

Regards,

 

Andrew

Hi David,

 

Thanks for the advice, but unfortunately as the computer went off as well, so the mill completely lost its marbles and also lost the program, so I have no idea where it got to. It’s now running again, as I type , on a new blank. I’m going to make a new blank to replace the one that was partly machined. The roughing cut is programmed to leave 0.2±0.1mm of stock. I don’t think I can realign in the A axis to that accuracy as there is nothing to reference against. It’ll only take me a few minutes to make another blank, but it is £2 down the drain in material.

 

Steve: I haven’t seen a three phase UPS either. As it happens the mill runs on single phase. Eh, what didn’t I intimate two phases above? The mill was designed in the US, so the main drives, controls and VFD are intended to run from a 220V supply, ie, 110-0-110. There is a separate, isolated, supply input, normally 110V, to run the computer and with a separate switchable output for things like coolant pumps. The isolated supply is also rated for 220V, so that’s what I use for the computer and coolant pump. I was a bit concerned about running the two supplies from different phases, but they have proved to be truly isolated, so everything is fine. I don’t think I could afford a UPS(s) with appropriate power ratings. Plus, my experience of UPSs for computers is that they don’t work. Several places I have worked have had UPSs fail to do the job when the power goes. The place I’m working at the moment had a big storm a few weeks ago and the power went off for about 8 hours. Not only did the UPS fail to protect the server, it committed hari-kari. There is now a pile of very swollen lead acid batteries on the floor awaiting recycling!

 

Regards,

 

Andrew

I do my CAD/CAM on a computer in the office. Only the computer in the workshop that was driving the CNC mill lost the program. Fortunately I still had a copy on the office computer, and on the pen drive I use to transfer between the two.

 

Regards,

 

Andrew

Posted by Andrew Johnston on 13/08/2011 11:14:20:

 

I have one UPS on a specific bit of kit, and because of where it’s used it gets exercised quite regularly and doesn’t give any trouble at all. I think in part it’s because it’s not a ‘cut in’ style one, but one that uses a relatively hefty supply that runs everything and float charges the battery, rather than one that’s just capable of charging it and relying on the switch-over to work. So effectively it’s running the device all the time.

 

As you’ve observed (and so have I), large storms can take out the control mechanism, and often everything else as well from a UPS just as easily as they can take out anything else that happens to get in the way!