What if and can I prevent it

[stk2008]

Hi all ive just had a thought about what if the power goes for some reason and im in the middle of a cut say a 3d relief the cnc mill will stop,pc etc etc.

Do any of you run some kind of back up or am i just worrying to much as its easy to refind the last position etc?.

cheers all

[kling8]

I wouldn't worry about it I have been machining for over 10 years and I have had that happen to me a few times, it kinda depends on the machine, I ran one when the power went out it crashed, no good, others didn't crash just stopped. But it doesn't happen much. I would say to cross that bridge when you come to it..
kling8

[Joe Cleary]

Backups are things you do to keep your software and/or programs safe from glitches.

If you mean how do you get back to the last place you were cutting, that's a different story.

The big guys in industry segment their cutting programs into sequentially numbered "blocks".
If the spindle/router has not drifted down into the part and ruined it, you rehome and go back to the block that was running and run from there. It saves a lot of time.

Otherwise, you home your CNC,and raise Z up a few inches. Hit run and watch until you get close to your last cut. This is called "cutting air". Then drop Z downthe amount you raised it and restart.

We have these neat anodized aluminum pins that go in the home position in all of our tooling. The cutter is programmed to cut around the pin and "kiss" the top of the pin. It does not dull the cutter and it's easy to see if the cutter is off in X,Y,or Z.

[jsheerin]

For the 3D printer we have at work (basically the same as our cnc machines, but it squirts out resin in layers to make a part), they have a battery UPS like for a computer. It interfaces with the machine control software. If a power outage occurs, the UPS keeps the machine and computer running but stops the machine and starts a power down sequence. This keeps the machine from clogging the print heads.

On my router, I've always just rehomed and restarted cutting at about the spot I left off (I typically start a bit before and cut air for a minute). This happened to me quite a bit before I ran some more power lines to my garage - I'd trip the breaker.

[stk2008]

Hi all thanks for the replys.

So if the power goes some times the machine can go nuts for a second and plunge?.

I have a kill switch that kills the mains power coming in if I hit that (must be same as if power fails) it just stops I see no movement of the machine at all it stops dead.

So if the power fails on a cut I should be safe as in the machine will just stop dead?.

cheers

[hemsworthlad]

Originally Posted by stk2008 Hi all thanks for the replys. So if the power goes some times the machine can go nuts for a second and plunge?. I have a kill switch that kills the mains power coming in if I hit that (must be same as if power fails) it just stops I see no movement of the machine at all it stops dead. So if the power fails on a cut I should be safe as in the machine will just stop dead?. cheers

Hi,

Yes and no.?
It depends a lot on what the machine was doing at the time, like if it was rapiding between positions and the power just goes of then you will always get a bit of overun which results in lost position same can go when cutting and it's a bit of a lottery to wether it stops dead or continues into the work.

If you have homing switches and it aint wrecked the work then it's not so much a big deal.
If you use mach and you have a idea where abouts in the code it stopped then you can use the "run from here" feature.
I do this often when things go wrong half way thru a job or a cutter brakes and doesn't ruin the job.
If like me you just throw a piece down on the bed and cut it there and dont have a set fixture offset that you use all the time then It's always a good idea to save the fixture offset before you start cutting.
I've had conditions where computer or mach as crashed part way thru a job and Mach only saves the fixture offset when you shut down, in a case like this even with home switches you wont know where your initial zero was placed because mach didnt save it before crashing and will start backup with the last fixture offset saved which most of the time relates to the last place you were at when you shut mach down.
I like to have a referance point on the work piece that i use as zero and can easily get back to if things go tits up and position is lost, a hole or corner anything that is easily repeatable and accurate.

While learning i made loads of self inflicted cockups and i,ve also had everything from power cuts to cutter breakages to the dam right stupid mistakes like tripping on extension cables pulling the plug out socket and this was good in some ways because it learnt me how to escape and salvage work that would other wise be lost.!!
Fortunatly know days the cockups are far less and i dont make so meny silly mistakes like chopping thru my hold clamps.? but they do still happen.!! . .The differance is i spot them quicker and 99% of the time i escape losing the work because i know exactly where to start from again and little tricks to help get back on track.

A probe is a great tool for relocating initial zero accurately and has saved me on meny occasions or made the task a lot simpler than it other wise would be.

With experience i would say 95% of the time you can recover from a powerout or crash without losing the work so wouldn't worrie about it too much, but with that said if your cutting very expensive materials then really it would pay you to have a UPS power backup but this wont save you from a PC or software crash.!!

Hope this helps.