Catastrophies: post yours to help others through their silly mistakes

[pdentrem]

I was turning the taper of a rifle barrel from chamber to muzzle. On the next to last pass I turned around to look at the drawing and heard crunch crunch. The carriage had stopped moving! What the ....? I stopped the lathe and looked towards the gearbox. Underneath the gearbox was a small pile of Zamac teeth from the two gears. Somehow the carriage hard tightened up and strained the 60 year old castings. Well that stopped the barrel work. Called Clausing and ordered those gears and a complete new set of the three. Also since I was getting that stuff I ordered all new bearings, bushings etc and a new lead screw before it was discontinued.
No injuries except to the bank account.

 

[Highpower]

You've got a great sense of timing Rick.... :holdphone:

I just pulled a bone headed move this evening. I have a hardened steel part that I wanted to drill through and tap in order to install a 8-36 set screw. I carefully set it up on the mill and found my hole location. Spot drilled with a 1/8" solid carbide drill bit, right where I wanted it. Changed over to a #29 carbide bit and drilled the part through - no problem.

I have the tap in the handle, the tap guide in place, and a can of cutting fluid at the ready. I only have HSS taps, and I've done this before successfully by going slow, backing up often, and not over doing it when turning the tap. I got all the way through the part and stopped twisting when the tap got easier to turn. hew: The little voice in my head told me to back out the tap and put away my tools. But no...........

I thought I would give the handle "just one more turn" to make sure the last thread was complete. SNAP! ~~ :angry:

Moral of the story? When the little voice in your head says something to you - LISTEN to it. It's right 99.999% of the time, so don't ignore it when it starts talking to you. About the time you start thinking "this is going to hurt if my hand slips"..... guess what happens? BELIEVE ME!

 

[Tony Wells]

I must have a good memory suppression system. I can't remember anything catastrophic as far as machine wrecks, but only a minor chuck tickle now and then. Scrap parts now are a different story. I have wrecked a few CNC machines when there was a program error I didn't catch proofreading the code, or making a bad offset or edit, but nothing worse than bending the index pin on the turret. Or having to re-bore the soft jaws after whamming a part with a 1.000 DoC pass. In rapid. That one was a surprise. I was just taking over and filling in for a really good operator who had just made an offset. He didn't think twice about it, and I trusted him. Cycle Start......Wham!

I'll try to remember anything more serious I did. I could tell about a few other accidents I know about, but I'll try to just incriminate myself. Some of those involve injury, death in one case, and many broken machines.

Oh, just thought of one. Daewoo ProTurn lathe. Flopped the steady rest open, so that it rested on the stop on the lower half. Had an indicator on the front turret, and was dialing it up to the part. The ProTurn has a handwheel just like a manual machine, but is a pulse generator to operate the servos in manual mode....slick feature. HOWEVER....I failed to consider the 2.5" boring bar on the rear turret that just happened to be lined up in a way to collide with the top of the steady rest. The bad thing about the pulse generator handwheel is that there is no feel, or tactile feedback. Sooo, I didn't realize I ran into the steady rest until the loud BANG of it falling off and hitting the back of the enclosed cabinet. Everyone in the shop (about 50 people) knew exactly what I had done, as I wasn't the first. I brazed it all back together and it was fine.

Found this pic on the net of the same model lathe, and it looks like the top half of the steady rest has been replaced....might be a common problem.

 

[blindstar]

When I got my first mill, a very old Baker #4 with flat belt drive through a Ford Model A transmission, I was really excited. I had spent the last few days disassembling, moving and reassembling it. Now I wanted to make chips, but I didn’t have a mill vice so I thought, just to test the machine, I would use a drill press vice and be careful. I was fly cutting a block of steel, running the mill in backgear. I took a light hand fed cut and the machine seemed to be cutting effortlessly. I engaged the power feed. About 3 seconds later the vice exploded. This was a long time ago but I seem to remember finding a piece of the casting embedded a nearby wooden column. I read this and wonder how could I have been so stupid, I knew better.

 

[duckman]

OK I'll admit to one bone head move, cuz if no one sees it it didn't happen. Many decades ago I was on second shift running a P&W tape-o-matic, had just got done center drilling a mold plate, put a 5/8" straight shank drill in the 3/4" Albright chuck, forgot to switch the depth switch, hit the go button, machine went to oh my god speed, rapid traversed into the plate about 3/8", when no one was looking went to the crib and got 2 24" pipe wrenches and loosened the chuck, got lucky there was just a little tiny bump when tightening the chuck. Fortunately the spindle was belt driven, the plate didn't move I got lucky, finished the job and just kept on working, this is the first time in 46 years that any one know's about it.

 

[Tony Wells]

Ahh, a shaper story.....


Bought a used 32 or 36" Cincinnati (can't remember size for sure). Had it brought in on a flatbed trailer, not a low-boy. It was properly right in the center. Not having a large enough forklift to reach out and lift it, and not enough sense to drag it over to the side, I called a nearby used farm tractor dealer/salvage yard and talked them into driving over one of their lifts. It didn't have the reach either, so in a Stroke of Genius, I decided to use both lifts, one on each side of the trailer and get under the machine. Lifting it just off the blocks, the driver pulled the trailer forward, leaving the machine 5 feet off the ground on the last foot or so of each set of forks. So far, so good. Now the idea was to slowly and evenly lower the machine onto blocks where I could get all the way under it. Here's the problem: The loaner forklift had a rather sticky hydraulic valve on the mast control. So, as I lowered my lift, the other operator lowered his.......until his got a little jumpy. My lift got a little lower, and the machine began to slide on the forks. Not having the foresight to have chained the machine off to both lifts, there was nothing to stop the slide. I yelled to the other operator to just lower as fast as possible, hoping to minimize the height of the fall. I dropped my forks, and his were a tad slower than mine, so the load slid my way, and off both sets of forks at about 4 feet up. The ground shook as the 8,000 lb shaper hit the asphalt. At least it was asphalt. It landed on a corner of the cast base, dented the asphalt a good 8-10 inches, and fell onto the side. This is the one time a machine (or anything else for that matter) did not land "butter side down". The only damage other than my ego was a broken belt guard. It was cast iron also, so a bit of brazing and it was good again. We used that shaper for 15 years after that. I don't know where it is now, but I knew where it was at the moment it was conforming readily to the Law of Gravity.

 

[Tony Wells]

You're right, it is out of character now, and even then it was. I was 25 years old at the time, and had moved an entire shop without incident before this bone-headed affair. I don't know why I didn't do things right, I knew better.

Sounds like you were very fortunate, in a way. It would have been better for the driver to have been more cooperative, but at lest you still have all your fingers. Sounded like a good way to lose them.

 

[bvd1940]

WELLLLLLLLL I had a 16" nylon gear blank I had to turn on overtime chucked up in a Graziano lathe that jus happened to have high speed range 2500 + and I had other things I wanted to do that night so I cranked it up full speed. Got a good lesson that day, that gear blank grabbed that tool bit and the gear blank was launched and hit about 15 different spots before I could blink (not even enough time to pee my pants)
Everyone in the shop just peeked around there machines and the foreman just ask if I was OK and went back to work.
I no longer push the envelope, I was young and dumb when that took place