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Machining confession thread.

I've never left the wrench on a Bridgeport head, but I have left it on the vise, often on purpose. What's not so on purpose is when I traverse X watching my part and the vise gets REALLY TIGHT as it hits the Y handle.
Did leave the chuck key in the chuck once on a South Bend 10L. I got lucky that it jammed against the ways after less than 90 degrees of rotation and just stalled it.
 
Watching a newer guy who had just learned the surface grinder because he wanted someone with a bit more time on the machine to be nearby.An 8x20 on batch of welded parts that were 6" square but 14" tall, all set in a line on the table. It's making that nice swish-swish-swish sound as it goes back and forth and coolant is running nicely. Everything is cleaned up so we're just sitting there waiting for it to come in to height as we watch one of the parts take a half second too long to change direction after the table reverses. Yep, forgot to turn the magnet on. Fortunately despite being so tall it didn't hurl the part and damage anything, but we both sat there just staring for a moment after I dove for the e-stop.
 
There's another thread asking about gas furnaces for hardening. I'll confess here for the sake of continuity. Gas bottles were outside next to the loading dock and had recently been moved. Went out and opened the gas. Loaded furnace and opened gas at furnace. Lit with lance through inspection hole. Carried on working then went over to talk to foreman who was working on lathe from where furnace was visible. Almighty boom and looked over in time to see furnace brickwork sort of settle in place and a huge cloud of dust. Rushed outside and turned off gas. Obviously everyone's giving advice about what went wrong. Went outside and tapped on the gauge, it had been damaged by fitters in relocating the bottles and was stuck showing full pressure. We use to harden everything in a cast iron box full of charcoal to prevent scale. Furnace must have heated box enough to be glowing hot. Gas went off and then back on because of pressure and re-ignited followed by large explosion. Now 33 years later I always tap all guages to check they aren't stuck.
 
Is it a confession if I'm ratting out the deceased? All parties have passed, including the company. Kind of machining related but, not my story...

An uncle worked his way up at a shipyard back through the 60s and 70s, eventually becoming the director or whatever, over the machine and fabrication shops.

He had a habit of having 'his guys' make little side things he'd see in Popular Mechanics or other sources. One of those was a model cannon. Problem was: he also didn't like the scale of some of these things so he'd ask whoever to double or triple the dimensions.

His friend goes off and fabricates this beautiful brass model cannon. He made the wooden carriage and all the little parts. The result was over a foot long and had a bore of something just under an inch.

What do you do with a model cannon? You fire it, of course. Problem was: neither of them knew much about black powder or cannons, or guns for that matter. They did the best they could. I'm going off the story my uncle told me at maybe 12 years old so don't kill me if the details don't seem plausible.

As he told it, they stupidly "poured some powder" down the barrel. Way too much in hindsight. They didn't have a proper packing so they shoved some torn up shop rag down there. Cannon ball? Hey, a ball bearing looks like a cannon ball! It's a weekend, the shops are all empty. They take this thing into a remote corner, wrap it in a towel and clamp it in a vise. They're expecting a pop, the ball being tossed out and maybe hitting the ground 50 feet away. The fuse is lit and she goes off with a much larger boom than they were expecting.

The bench slides back a foot or two. The ball goes straight through a cinder block wall on the other side of the very large building. It buried itself firmly in the hill behind the building. Panicked, they took the cannon out of the vise and tossed it in my uncle's trunk. Security sends out a car because--big bang noise. My uncle quickly came up with a story about knocking over a large pallet that was stood upright. The sound was the slap of wood against the ground. Security bought that and left.

Having two teenage sons at home, my uncle realized what a terrible idea it would be to have this thing around. The friend filled the primer hole and turned it smooth. They almost got caught with it while doing this work and they never finished cutting off the back of the raw bar and finishing the knob.

He gave me the cannon around 1978-1979, under the condition that I'd never drill out the primer hole and make it operational again.

In college, I took an introduction to Manufacturing class (lathe, mill, shaper, etc) where I asked if I could bring it in and cut off & finish the back of the cannon. Firearms weren't allowed and I was trying to get an exception. The instructor looked at me shocked and said, "Man, you can't finish it. You'll ruin the story! That unfinished back is the only proof you have that it ever happened! You finish it and it's just another cannon." He was right and that's how the cannon exists today.
 
We used to have a lathe with an L1 spindle. I hand tightened the retaining ring, went to get the big hook spanner, got distracted, came back and started up the spindle at about 800-1000rpm. It was real wobbly for a second and came off before I could fit the switch. Lucky me I wasn't in it's way and it came off going down and not up. Put a little dent in the side where it hit a hard V way and chipped the concrete a little, but after changing my pants I mounted it proper and went back to work (denying I knew wher that loud boom had come from).

While we're talkin' confessions, It was me.... I'M the guy who put all those air hoses on all our mills and lathes! I'll do it again too!
 
We used to have a lathe with an L1 spindle. I hand tightened the retaining ring, went to get the big hook spanner, got distracted, came back and started up the spindle at about 800-1000rpm. It was real wobbly for a second and came off before I could fit the switch. Lucky me I wasn't in it's way and it came off going down and not up. Put a little dent in the side where it hit a hard V way and chipped the concrete a little, but after changing my pants I mounted it proper and went back to work (denying I knew wher that loud boom had come from).

While we're talkin' confessions, It was me.... I'M the guy who put all those air hoses on all our mills and lathes! I'll do it again too!
One place I worked the maintenance shop had a grouchy guy who did a bit of milling, turning, grinding etc for the fitters. He was always moaning about the state some of the guys left the lathe in when he wasn’t there.
One day he loosened the locking collar on the chuck deliberately before he went home “ To teach us a lesson “ !
Same thing happened as you described. Nobody got hurt but it made the guy who switched it on jump a bit.

Regards Tyrone
 
Flywheel I was boring, .020” to come out. Put on a .010” cut. .020” too loose The old lathe (churchill-Redman)had a .250 dial on a .500 screw!
 
Sometimes the stars align. Ran a 1920's Oerlikon lathe with a screw on chuck no locking collar. Had a big lever on the top. Middle was stop then low to the right and high to the extreme right. Left was reverse in the same order. I was finishing a core for a flip top cap mold. Put it in high to polish it, finished polishing and set lever to middle to stop the lathe. The slight hesitation going through low was enough to unscrew the large chuck with it's own inertia. Chuck bounced on the bed a few times took off and hit the pillar behind the machine spun a few times and fell over. I was thinking time to make a new core. Not a scratch on the core and apart from a few dings to the chuck, carriage and my ego a lesson learnt on being really careful when changing speed or stopping that particular lathe.
 
11 1/2" dia, about a 4" face, 4340 :(

That's even less than pint-sized to some people, I know a story about a effed-up gear at Westinghouse that cost $250,000 .... and it was the pinion. That'd put a knot in yer panties :(

Yeah I used to see gears bigger in diameter than that in *feet* regularly.
 
I worked for the Kyocera company in their fine ceramics division grinding one rock with another rock. I also done the green machining when I first started there. We had a guy that worked there that decided he was going to use pie jaws to chuck up on the ID of a rather large green ceramic ring. Green ceramic does not like internal pressure to begin with. Once it's fired it does much better. Well he chucked up in the id( 3 jaw scroll chuck) and started running the part. Well Hass tl3 does not have much for a cover. We had a vacumm cover made with a window in it to watch the chuck made so that the suction would pull the dust while parts was turning. He watched through the window with his forehead against the glass. About 2 cuts in boom. Part exploded, he shit himself and went home.
 
I worked for the Kyocera company in their fine ceramics division
Ha ! Busted !

Someone once gave me a box of kyocera 'cermets' ? that were incredible. Sharp on the edges, not like ceramics, but cut like ceramics, sparks flying everywhere, hard steel, stainless, never tried aluminum but anything tough ? dry ? hard ? them things were absolutely killer. And the finish ? shiny shiny, shiny boots of leather.

And after the box was gone, I could never find them again. Any idea what they were ?

eKretz said:
Yeah I used to see gears bigger in diameter than that in *feet* regularly.
And someone has to make the machines that make the teeth on the gears ten feet in diameter :D

gasher.jpg

(I'd come up with another screwup story just to keep on-topic but unfortunately that's the only thing I ever screwed up ... unh-hunh)
 
Several of these stories reconfirm that making tiny parts is the smarter path. Most of the time, if I screw up, well, there goes $4 in Titanium and a $30 cutter. Fix the program, put in new stock and cutter, and go. I think the worst single loss was a $125 slab of PEEK.
 
Flywheel I was boring, .020” to come out. Put on a .010” cut. .020” too loose The old lathe (churchill-Redman)had a .250 dial on a .500 screw!
That reminds me of another one.
I had the job of replacing the cross slide leadscrew and nut on a big “ Craven “ lathe. I took out the old screw, measured everything, made a drawing etc. Then my drawing was sent out to “ Halifax Rack And Screw “ for them to make the screw and nut.
About a week later the new screw and nut came and I fitted the pair. I finished just before the night shift came on and I had a brief chat with the operator, then I went home.
When I came in the morning the guy was stood by the clocking in machine. I said “ How did you go on with the new screw and nut Kenny ? “
He said “ Fine, but what I can’t understand Tyrone is when I put a 0.200” cut on it only takes 0.100” off ! “
After about 5 minutes it dawned on me - the old screw was a two start thread and I’d never noticed ! I’d made the new screw a single start !
We had to have another new screw and nut made and I swapped the old/new one out.

Regards Tyrone
 








 
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