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đź’Ą What's Your Worst Machining Mistake?
by Morning Machinist
Jon House
December 14, 2025
💥 What’s Your Worst Machining Mistake?
Every machinist has that moment — the one mistake that lives rent-free in your mind years later… and usually in your coworkers’ minds too.
This week, a machinist in the group shared a story that kicked off one of the wildest comment threads we’ve seen in a while:
“I was wet grinding carbide with almost no coolant so I could see the touch-off… walked away for lunch… came back 10 minutes later to find the diamond wheel exploded and a $1,000 carbide cookie cracked clean in half.”
Running .0005" passes bone dry will do that.
But the comments?
The comments were a museum of catastrophic shop lessons.
Here are some of the ones that stood out:
🔧 1. The Mazak Missile Strike
Sent a tool into a Mazak Quickturn Nexus 450 at 100% rapid, 18" chuck spinning at ~2000 RPM.
The tool below the active station took the hit and literally punched a perfect square hole in the turret housing.
Shattered the linear bearings. Bent the ballscrew.
Knocked the head out 1/8".
A Âľ" solid carbide bar? Vaporized.
The dent is still there today — a permanent museum exhibit.
🌪️ 2. The Haas Tornado Drill
Typed RPM and M3 on different lines.
The machine ignored the 800 rpm command and defaulted to 10,000 rpm from warmup.
A 14" Ă— 0.750" drill instantly turned into an upside-down helicopter before snapping off and obliterating the window on their brand new Haas.
đź’¸ 3. The $800,000 First Week
Power flickered.
ZerÂos reset.
New guy hit Start on a vertical lathe.
The spindle went full send into the turret and scrapped an entire machine worth $800k.
First week on the job.
Legends are forged quickly.
đź“Ź 4. A $40,000 Decimal Point
Meant to enter 0.010.
Entered 0.100.
Scrapped a $40k part.
We’ve all feared this.
Bonus: His coworker once filled the coolant tank on Sunday…
and left the water running until 6 a.m. Monday.
đź’Ł 5. The Die Section That Tried to Kill Someone
Grinding a 350–400 lb die on a 24×48 Okuma.
A threaded insert backed out… and the wheel hit it.
“It sounded like a bomb went off.”
One chunk flew 2 inches past his face.
The grinder allegedly bounced off the ground.
Coworkers peeked over like meerkats.
Boss walked over and calmly asked:
“Are you okay?”
That’s real leadership.
🌀 6. The 12-Foot Whip of Doom
Coworker loads a full 12 ft bar into a non-barfeed lathe.
No whip tube.
Spinning 1" stock at 2,000 rpm.
When the tool hit center, the bar turned into a steel noodle of destruction and:
Destroyed his own lathe
Destroyed two more lathes next to it
Caused 300k+ in damages
Loudest noise the shop had ever heard.
🪟 7. Didn’t Turn On the Magnet… Hit the Owner’s Car
Nothing more needs to be said.
🎯 8. OD vs ID Chucking… Choose Wrong & Yeet the Part
Twin-turret VTL.
Wrong chucking mode.
Fired it up.
40 lb casting launched itself into a wall divider — still crooked to this day.
⚰️ 9. The Slant-3 Catastrophe
Set absolute zero at the chuck by accident.
Hit cycle start at 2300 RPM.
The turret went from home to -12.000" directly into the jaws.
One jaw ripped off
Two more bent
Turret housing cracked
Machine totaled
Machinist traumatized for 15 years
We salute this survivor.
🧠Why We Love These Threads
Machining is unforgiving.
Tolerances don’t care.
Offsets don’t care.
Gravity definitely doesn’t care.
But machinists?
Machinists share these stories so the next person doesn’t learn the hard way — or so everyone gets a good laugh and a reminder:
If you haven’t made a catastrophic mistake yet…
you just haven’t been in the trade long enough.
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