What was the dumbest machining mistake you ever made?

Don B said:
So on the walk to the river to dispose of the evidence he tells me for years he's been dragging the ones he screws up home and filling an old hand dug well but the well is filled and since then he's just been throwing them in the river...!:lmao:
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At the current price of scrap metal that well could become a sort of mine :D
 
atwatterkent said:
Need I say more? FYI checking the depth of cut without shutting off the motor on my horizontal mill can suck in your finger. Cut down to the bone.
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Ouch... I hope that healed-up ok for you.


Ray
 
I turned on a drill press at Penland Craft School,where I was teaching in the summers. It was a very unusual old Oliver(I think) with double columns,and a variable speed reeves drive.

Someone had left an 18" long lamp drill in the chuck,and the machine was set to run 3000 RPM!! Well,I don't know how they were using that bit at that speed. The drill straightened out sideways and broke off,going flying. The variable speed was unusual,and I didn't realize how it worked. After that,I was more careful!!

This is what happens when you work in a shop open to every college clown and "artist" who comes in. No reason a drill press with an 18" bit should be left on 3000 RPM.

I went to college,and I consider myself an artist. The thing wrong with most artists,though,is they have a huge void about technical info,such as how to use machinery. Over at the Physics machine shop at Wm.&Mary, in the student's machine room,I saw things like old fashioned Armstrong tool holders,clamped in lantern type tool posts,but clamped at their EXTREME butt ends(REALLY!!!),instead of up as close to the cutter as possible. What kind of physicists are using these machines? Ever learn about LEVERS???
 
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Most of my dumbass machining mistakes were/and still are a result of not clamping down securely enough, insufficient work holding, chucking up securely etc.... Usually ends up with a scrap part ,or worse, like something flying off at an unknown trajectory. :bitingnails: It usually ends badly, but could have been much worse:phew: Work holding is the biggest challenge for me in machine work IMO.:thinking: You can never have enough work holding tricks up your sleeve.

As a matter of interest, I think we should start a sticky thread solely dedicated to work holding solutions with lots of pictures from those that have come up with clever solutions.
:anyone:

Marcel
 
xalky said:
As a matter of interest, I think we should start a sticky thread solely dedicated to work holding solutions with lots of pictures from those that have come up with clever solutions.
:anyone:

Marcel
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:thumbzup3:
I agree!
A good work holding is fundamental for safety!
Even the smallest work can start a Rube Goldberg machine, into a crowded shop, and safety goggles are not very effective if an unmanned 6" Kurt vise fly toward your head at 200 mph.
 
george wilson said:
I saw things like old fashioned Armstrong tool holders,clamped in lantern type tool posts,but clamped at their EXTREME butt ends(REALLY!!!),instead of up as close to the cutter as possible. What kind of physicists are using these machines? Ever learn about LEVERS???
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Which begs the question, which has puzzled me for a while, why where they made that long?

Bernard
 
That is a good question. Perhaps to make them reach into the occasional deep recess? Who knows. Possibly to trip up physics students in college who could not remember their 8th. grade physics?

Maybe to provide decently long enough handles for those who ground their bits while in those holders.
 
After nearly 20 years as a interstate automobile relocation engineer ( car hauler ) I. Learned that all good stories of destruction start with the words. I was in a hurry.
I only totaled one new auto. Just lucky I guess.

Thanks scruffy
 
One more story recently told to Me by a friend. He has a lifetime of experience as a machinist and is retired now. One day He had to make a long shaft from 9" round Inconel, He was told that a Navy Sub was waiting on the East Coast for this part. UPS driver was setting in the truck to deliver immediately. Naturally He tuned a bearing surface down .200 to much. Naturally there was not a stick of that size anywhere in the USA to be found. Don't know what happened to the ship, but He got to leave early that day,........... with His tools.:panic:
 
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I was recently making a part that had a leadscrew running through it. 6-32. I drill for 10-32 by mistake! (used to grabbing a #21 drill, as a tap a lot of 10-32. So I get out some stainless to make an insert and bore for 8-32! What a dummy! Luckily, the 8-32 tap drill was missing from my index so I used one of a smaller size so I was lucky I could still tap it for 6-32 even though it was almost 8-32 hole.

So much for thinking, or at least using the tap drill chart in my drill index.
 
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