Whats the most expensive damage you've done to a machine

[M@T]

I did a good one the other week. Was machining a 150 mm shaft which I had to turn round halfway through. Accidently put one in the wrong way round and it smashed into it. Tailstock was in aswell so it couldnt rip it out the jaws. I also wasnt by the machine as i'd walked off to talk to the boss of all people. Oh the look on his face when it the machine started wrecking up

Ripped the jaws off the chuck, smashed the component up, melted the tool to the component and knocked the turret way out of alignment.

All in it was a pretty good smash

Best ever was when my boss made exactly the same mistake I did with exactly the same component except he broke the gearbox and bent the lead screw so the machine now cuts in a spiral fashion when turning long shafts.

[Klox]

Ouch! It brings tears to my eyes to hear of things like this...

Klox

[Turbine]

Ya had ta ask
None of mine sound as disastrous as yours.I had a thing for doors a couple times. Both times we pounded out the dents ourselves with a hammer. One was 1st thing in the morning when zrortn a machine whos vise was hanging over the front of the table.(took the door and stuffed it all the way to the left and then some) Another was leaving a vise handle in while doing a pallet change in a horiz. machine.
Way back we had an big old gear driven Cinci. milling machine.We allways left spindle turning to keep it warm. The arbor was wearing a 5/8 wide 8" dia. stagger tooth cutter the day that someone kicked the up feed while leaving for break. It milled it's way right into and almost through the table before it stalled against the arbor support.

[NeoMoses]

The worst that happened to me happened on my old dovetail Z-axis mill/drill that was converted to CNC. I was using a 1/2" HSS endmill to cut through 3/4" aluminum. Unfortunately, the z-axis was not locked, and creeped downward, through about 1/2" of aluminum, and then into about 1/4" of the cast iron table. The sound was getting horrible, and I was just reaching for the E-Stop button when the R-8 collet shattered!

I ended up with a tool mark in the table, a broken 1/2" collet, and one seriously dull 1/2" endmill. Amazingly, though, the endmill did not break. Needless to say, it was a memorable lesson to always lock the Z axis before cutting.

[M@T]

I've seen a lot worse than mine I can tell you. 2 spring immediately to the front of my mind.

1, a bloke I worked with a few years ago was machining some brake disc's and put a G0 instead of a G1 and rapided into the part ripping the disc out the chuck which banged against the door and ripped the door off the rail and also ripped the tool setting arm probe off next to the chuck and the whole lot ended up on the floor

2, less violent but still ££££'s of damage. A bloke was on a machining centre and left one of the clamps unclamped so it was swinging around inside the machine. As it was a small machine it was very tight inside and when the table tried to rotate inside the clamp got stuck but the machine tried to force it round and cracked all the casing that the motor was in. Had to completely take the machine apart to get at it which took hours and the spare casing alone was £500

[Turbine]

Without getting into details I heard one about an extremely large casting getting knocked off it's pallet, crashing it down into the machine on the ways due to a Z neglect function.Extraction involved opening a hole in the roof and using a sky crane to fetch it. Not good.

[hardmill]

WOW, WOW and DOUBLE WOW
I want to party with you guys.
I think the worst I've done is snap a boring bar or drive a
drill into a part (nothing too extreme).
Oh there was the indicator that did'nt pass the 15,000 rpm
test. They just dont make em' like they used to.
But you guys got some stories for the grandchildren.

PEACE
...and please be careful!!!

[timf]

i got g90 and g91 backwards in a horizontal machine on my g28 z0 line.
the tool and holder hit the tombstone at warp speed and shattered the one of the cones that locate the pallet underneath it.
the whole tombstone/pallet had to be taken off down to the cones.
had to replace cones, have pallet checked for damage, reassamble and scrap it all back in.
i was standing there watching it when it happen with the e-stop at arms reach and still couldn't react quick enough to stop it.
the machine rapids at like 1800 ipm.
oh yea, did i mention the machine was less than a year old.

[HuFlungDung]

Lol, Timf,

Ever wonder why there is a rapid speed override knob and a single step switch on the control?

I learned this too, but I only broke off a small boring bar when it got a little close to the chuck. Every program I set up on the lathe now starts with the rapids at 25% until the program has run through once.

[ty1295]

A few years back, on a twin turrett LC30 Okuma lathe an opertor crashed it into part/chuck so hard, when you opened the door, the upper turrett was laying on the chip conveyor.

[Fish]

A shop near me had a little crash about two weeks ago that cost a few bucks to correct. They have a large CNC VTL that they use to machine these pump castings that weigh over two thousand pounds each. Apparently, the operator forgot to make sure everything was buttoned down securely, when you guessed it, the part came off the table. It didn't damage the VTL, but it took out a wall next to the VTL, along with the little Fadal vertical that was behind the wall. The vertical was scrapped. Good thing it was night shift and there wasn't anyone on the Fadal. The operator packed up his stuff and took off - they haven't heard from him since. Ooops!

Fish

[Turbine]

hardmill,
The Brown and Sharpe Best Tests handle the spin test pretty good. They just have to be held with a holder that can pass the spin test (havn't found one of those yet) The impact is what kills the indicator