# POTD . What did you BREAK in the shop today ?



## mmcmdl (Feb 24, 2019)

Multiple carbide end mills . Machining broken taps out of extrusion dies .

Unfortunately , the endmills were mine , not works' .


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## Z2V (Feb 24, 2019)

I feel your pain Dave, I broke three Micro100 1/8” endmills this week myself. I did finish my part before I broke the third one though.


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## stupoty (Feb 24, 2019)

I had a lovely dormer carbide end mill which I got for a good price on ebay NOS.

I forgot to tighten a gib probably the second time i used it and the part grabbed taking out two flutes , it now lives in my box of shame along with a few taps and other end mills I have been bad to.



<-- smiley face covering face palm desire.

  Stu


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## PHPaul (Feb 24, 2019)

Well, I must say I'm shocked.  I've never broken a drill bit or burned up an end mill or trashed a nearly completed part because I forgot to tighten the vise.

Nope, not me.

Very often...


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## Boxster9 (Feb 24, 2019)

First time I broke a Cobalt 31/64 drill bit drilling some darn hard aluminum.  So much for China made drill bits.


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## BGHansen (Feb 24, 2019)

I've smoked a few end mills on the Bridgeport when running a CNC routine.  Lack of chip removal was the problem.  Nothing like letting a routine run on its own while doing other work at the workbench, hear a funny noise, look over at a red-hot carbide end mill travelling around the part.

Of course, snapped off drill bits, broken taps from trying to get one more hole out of a dull one.  Snapped off carbide inserts on the lathe while parting or turning.  

Bruce


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## Aukai (Feb 24, 2019)

Sorry wasn't in the shop today, but I did manage to wrap the bottom wire from the chain link fence around the lawn mower shaft.


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## turnitupper (Feb 25, 2019)

As someone on another forum was wont to say, Clumsy Bastards!
John.


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## bretthl (Feb 25, 2019)

THE BANK.


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## westerner (Feb 25, 2019)

bretthl said:


> THE BANK.


Very succinct. Quite funny. More truth than poetry. I am struggling to come up with anything more comprehensive, accurate or timely. I will take my place amongst the "clumsy bastards" and call it a night.


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## ddickey (Feb 25, 2019)

Broke another tap today. Nice one too, YG-1 Spiral flute.
I think the hole I drilled was undersized as I'd sharpened the bit several times.


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## JimDawson (Feb 26, 2019)

I broke a tap also.  But this one was a little different, it was a rounding error in the math.   A bug in my CNC program in the rigid tapping routine.  The machine was supposed to start at +0.200, move in to -0.875, then retract to +0.200.  Well it moved in to -0.875, then retracted to -0.344, then decided to rapid out to +0.200.....SNAP.  We have rigid tapped thousands of holes and not had a problem, but this time conditions were different enough that the bug showed up.  It's these types of things that make you crazy 

Found that I had set a variable to Integer rather than Double as it should have been, and in all cases prior to this setup it was *rounding up* to the nearest integer, but in this case the dimensions were such that it *rounded down*.  Fixed the software and then tapped 250 5/16-18 blind holes, 0.875 deep in 304 SS with no problem.  Spiral flute machine tap, after 250 holes it is still sharp and cutting fine.


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