# Don't leave the key in the lathe chuck



## Jake2465 (Jan 1, 2018)

Very first mistake I made when I started running a lathe for the first time. I fired up the lathe and all I heard was something smack the wall about 20 feet away. Come to find out, it was the lathe key. I thought "woah!! if that hit my face I could have been hurt bad" . Never did that again.


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## woodchucker (Jan 1, 2018)

yep, been there done that.


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## Ken from ontario (Jan 1, 2018)

Jake2465 said:


> Come to find out, it was the lathe key. I thought "woah!! if that hit my face I could have been hurt bad" .


It even hurts thinking about it. I've seen it happen once a few years ago, didn't hit anyone but you should have seen the operator's face after he realized what had just happened.


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## Cooter Brown (Jan 1, 2018)

Yup I've made that awful mistake when I got my first south bend lathe, everyone really should do it at least once that's not a bad thing to absolutely fear doing again.


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## Jake2465 (Jan 1, 2018)

Ken from ontario said:


> It even hurts thinking about it. I've seen it happen once a few years ago, didn't hit anyone but you should have seen the operator's face after he realized what had just happened.



I can only imagine. Carelessness has no place in a machine shop. 

The next good lesson I learned came about 6 months later when I cut my finger joint real good over not deburing an aluminum edge. I thought that surely it cant be that sharp. After all, it's a 90 deg edge, not like it's a knife or anything... Some days that joint still reminds me of that time.


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## Jake2465 (Jan 1, 2018)

Cooter Brown said:


> Yup I've made that awful mistake when I got my first south bend lathe, everyone really should do it at least once that's not a bad thing to absolutely fear doing again.



That's what I did it on, lol. Even a 1hp lathe can get scary real fast .


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## Cooter Brown (Jan 1, 2018)

This looks safe right??


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## 4GSR (Jan 1, 2018)

Cooter Brown said:


> View attachment 252693
> 
> 
> This looks safe right??


I'm sure it's OSHA certified.


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## woodchucker (Jan 1, 2018)

Cooter Brown said:


> This looks safe right??


That depends, safe for what?


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## kd4gij (Jan 1, 2018)

Depends on the operator.


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## dave_r_1 (Jan 1, 2018)

been there done that.  my lathe doesn't seem to throw them, just busts off the tip, rendering them useless.


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## buzzkill (Jan 1, 2018)

Just did that today... what can I say I'm a noob.


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## jrkorman (Jan 1, 2018)

I took metal shop in 9th grade (1971-72) - Our shop teacher taught us to rotate the chuck by hand
at least once before applying power. Still do that now, especially good when something has
sidetracked you.


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## Z2V (Jan 2, 2018)

My chuck keys have springs on the end. When I first got them I thought “ what a pain in the butt” and took the springs off. After realizing the accident potential I put the springs back on. I just can’t see slinging a chuck key through the windshield of my car parked in the garage with the lathe.


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## magicniner (Jan 2, 2018)

I have chuck keys on Tool Balancers over the lathe which keep them at an ideal height to grab but automatically retract when you let go of the chuck key. 
I used a chuck less than 10 times last year though as my lathe has a native ER40 spindle nose which covers 99% of what I do in the lathe.


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## Ray C (Jan 2, 2018)

Z2V said:


> My chuck keys have springs on the end. When I first got them I thought “ what a pain in the butt” and took the springs off. After realizing the accident potential I put the springs back on. I just can’t see slinging a chuck key through the windshield of my car parked in the garage with the lathe.



Consider yourself lucky if you only get a broken window.   I don't know of a specific case, but wouldn't be surprised to hear that people have lost their lives making that mistake.   

Over the years, I've trained myself to never, ever, ever take my hand off the key until I'm putting the key away in it's designated spot.  

Ray C.


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## 4GSR (Jan 2, 2018)

Don't do what I did when I was 10 years old.  I managed to flip the drum switch on with my left hand on dad's 9" South Bend lathe with my right hand on the chuck key tightening down on the work piece.  I thought the end of the World came and flashed in front of my face!  My right hand was caught between the chuck wrench and the bed of the lathe and the 1/4 HP motor was cycling trying to run until dad came over and turned it off.  Probably all happen in less than 5 seconds.  My poor hand hurt for two weeks!  It didn't break anything, didn't even bleed!  But had a bump on the back of my hand for nearly 40 years until my RA hit it and went away.  You gain a respect for chuck wrenches and drum switches! 

Ken


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## 4ssss (Jan 2, 2018)

When I was in Trade School, if you got caught leaving the key in the chuck, the Shop Teacher had one mounted on a chain and you wore it around your neck for the week you were there. Now, just about every Craigslist ad I see has the key sticking out the top. Guess they stopped doing that.


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## bluechips (Jan 2, 2018)

I happened to be watching a person start spindle on a (large) modern conventional lathe with a forgotten/overlooked 5/8"  t-nut in the slot on a face plate.  The spindle speed was fairly high.  The nut flew from the faceplate hitting him in the shoulder and sat him down on the floor in front of the lathe with a bewildered look of both pain and surprise on his face.


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## aliva (Jan 2, 2018)

My lathe came with a chuck cover. The cover must be in the lowered position in order to start the spindle. I have taken it off in order to turn some large items but it goes back on as soon as I'm done. With the cover down you can't leave the key in the chuck


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## Bill Gruby (Jan 2, 2018)

I believe one of our members made a holder for the key that would not let you run the machine unless the key were in it. Can't seem to find it now. Anyone else remember this??

 "Billy G"


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## Z2V (Jan 2, 2018)

I vaguely remember a post along those lines. A good idea and shouldn’t be too hard to do.


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## 51cub (Jan 2, 2018)

I remember something about it, too. It's a good idea. I only remember leaving a chuck key once, hopefully I learned from it. I can't read things like this too often, though. I'm forever doing things that I know better than to do, but I get sidetracked, lazy, interrupted, forgetful- you get the picture


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## Doubleeboy (Jan 2, 2018)

Bill Gruby said:


> I believe one of our members made a holder for the key that would not let you run the machine unless the key were in it. Can't seem to find it now. Anyone else remember this??
> 
> "Billy G"



It was in Machinist workshop magazine
michael


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## kvt (Jan 2, 2018)

I remember it but think it was in a thread someone else had going on something.


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## Bill Gruby (Jan 2, 2018)

Well at least I wasn't dreaming. It's not in the safety area. Gotta find that one.

 "Billy G"


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## kvt (Jan 2, 2018)

I do not get that mag, but remember it thus either on here or youtube or something.


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## 51cub (Jan 2, 2018)

Doubleeboy said:


> It was in Machinist workshop magazine
> michael


He might be on to something here. This sounds familiar


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## fradish (Jan 2, 2018)

The human mind is a weird thing.  I NEVER left the key in the chuck until I read a post about people
doing that and then I ended up doing it.  Just the once and luckily I didn't turn it on before I removed 
the key, but its weird that I never did it until I read that I shouldn't...  And I'm not a rebel or anything,
just that it never occurred to me to do it until I read that other people did it...


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## EmilioG (Jan 2, 2018)

Twice, I almost left the key in. Both times I looked and removed it.  A friend made a lathe chuck key with the spring ejector.  You have to hold the key in to use it, if you let go, it ejects.  Like some Jacobs chuck keys with the ejector pin.


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## Superburban (Jan 2, 2018)

Also do not dare think you are stronger then a lathe.


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## Z2V (Jan 2, 2018)

Holy Cow


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## 4GSR (Jan 2, 2018)

Not again!


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## Z2V (Jan 2, 2018)

4gsr
I take it that video has made its rounds before?
First I’ve seen it, OUCH


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## Bill Gruby (Jan 2, 2018)

Several times. LOL  There are many out there on the net that are much worse.

"Billy G"


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## kd4gij (Jan 2, 2018)

https://www.google.com/patents/US20160158849


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## Superburban (Jan 2, 2018)

4gsr said:


> Not again!


Sorry, Didn't intend to dredge up old memories. 



kd4gij said:


> https://www.google.com/patents/US20160158849


I don't get how that patent was ever approved. I can think of several machines where you have to insert the key in a holder in order for the machine to operate, including this old wards drill press/ overhead router combo. You can see the key inserted on the bottom right side. Made well before the 2014 patent.


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## Bill Gruby (Jan 3, 2018)

To get a patent  one has to show a significant difference or improvement over the old one. Building a better mouse trap so to speak.

"Billy G"


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## Superburban (Jan 3, 2018)

I understand how patents work. I don't see anything new, or better. I think the examiner was asleep when he/she approved that one.  Ok, when I went back to see who the examiner is, I see it is still in the application stage.


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## 4GSR (Jan 3, 2018)

Not to get off subject, I have three patent certificates hanging on my wall that were issued to me and three others involved.  (Really me and one other were the ones involved in the actual design submitted. Other manager/owners had to have their name on the patent, too) One of them, was back in November.  Anyways, the first two, we never dreamed we would get them approved and accepted and they were.  And like Bill said, it only has to have one minor change to make it different and get issued a patent.  
The patent laws are going thru some major changes as we speak.  Some of it is law now and some of it is still in work in process.  It will make it much harder to get issued a patent on just a minor change in the product.  And it gets deeper than that and I'm not up to date on any of the changes being made.  And regardless, it takes a patent lawyer who knows the ins and outs to get a application across the line and accepted for review.  Oh, and lots of money, too!

Ken


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## epanzella (Jan 3, 2018)

I never leave a key in the chuck even when leaving it for a second. I use 2 keys to dial in a 4 jaw but the lathe power is off and the gears in the headstock are disengaged.


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## Silverbullet (Jan 4, 2018)

That machine don't know or care. Not to long ago on a YouTube there was a guy got twisted up in a lathe spun a bit and fell out. Later on he died from the injuries . Really it didn't look like he was hurt that bad must have mangled him inside. It was tuff to even watch . I've been knocked over by forklifts with idiot drivers a solid tire one mashed my steel toe right through the sole on one foot another time. I'm sure glad they were on ..  SAFTEY isn't no  toy to play with. Bad enough getting hurt , if it's preventable PLEASE BE AWARE AT ALL TIMES.


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## mcostello (Jan 5, 2018)

There was a video of a guy caught on an automatic lathe, ducked under a 2" bar that must have been turning at least 500 rpm. Dead on the second revolution, spun till He was a bag of skin. No one there to shut it off, He was working alone at night. The only way they figured out what happened was security camera footage.


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## Terrywerm (Jan 7, 2018)

Here is an old thread that discussed a solution that one of our members came up with and posted on his website:  https://www.hobby-machinist.com/thr...through-the-windshield-of-your-porsche.30440/

The short version is this: He made a chuck key holder from a piece of pipe or tubing. Inside the tube there is a microswitch that is wired into the run/stop circuit for his lathe. In order for the late to run, the chuck key must be in its holder, closing the switch.


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## blue_luke (Jan 12, 2018)

Done that too, got scaried to die there!
I am an industrial electronic tech.
So all work on my new lathe projecs was stopped immediately to solve this very important safety problem and there is an easy fix for it.
Here goes....
Most machines have an emergency switch or ES "loop" that consist of a circuit comprising the 'mushroom' some limit switches and whatever should prevent or stop the machine if anything is wrong. It is a simple manner to make a chuck key holder where a microswitch will be activated when the key is in the holder. This way, no key? no run!
The idea is just open this loop and add one or two more microswitches in the circuit.
I made mine from wood. The keychuck is inserted in a hole and close the contact when in. I made it to hold both the 3 jaws and the 4 jaws chucks since they are a bit different.
If any of the keys is missing, the lathe will not start, simple, efficient, safe!

I also made a pair of microswitch holders that I can set anywhere on the V-way of the lathe so that when the carriage hits either one (going L to R or R to L) the machine will stop. Guess how I came with this one!
I had once the tool post hit the chuck,  this broke the alorris type tool holder.
I also had the carriage bang in the tailstock, this case it broke the shear pins on the drive shaft!
Newbee errors, but dangerous newbee errors!

When I told about tis to my boss at work, he found this quite clever and commissioned me to go around all our machines in the workshop, but also on the production floor to see how I could make the machines safer, more idiot proof.
It took me almost a year to go about the whole plant!

Luc


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## ch2co (Jan 12, 2018)

I was a 9 year old when I left a key in dad's drill press and turned it on. Fortunately no one was injured but the chuck (Chuck's chuck?) flew
across the room and smashed into a chemistry experiment that I was working on (a still) consisting of 2 water cooled condensers two 
large flasks and a beaker, all glass, were reduced to small pieces as well as cooling water pouring out on the bench and the contents 
(very colorful) were smeared all over the wall, bench and floor quite a mess to clean up and financial loss for me. Now almost 70 years later, that same guy still gets a very tight sphincter whenever he hears talk of leaving keys in chucks. My drill press has a short chain on the chuck with a pin that pushes the key out of the chuck when you let go of it. It works quite well and isn't a nuisance to use. My little mill chuck is an Albrecht that doesn't use a key. My lathe came with a chuck key that has a spring wrapped around the square boss but is a pain to use. I use a rube goldberg key consisting of a 10" long 1/2" socket extender with a small ratchet wrench on the one end and the other end fits quite well into the chuck. This works like a charm for my needs. My only other keys fit into the various locks around the house. 

Thats how I've stayed grumpy.


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## hman (Jan 13, 2018)

I'll start out by saying that I like and appreciate EVERY ONE of the "safety interlock" ides that have been presented here.  But I've hesitated doing this.  I personally prefer to always be conscious and careful, and not get dependent on external devices.  Maybe I'm paranoid, but I'm concerned that I could get complacent, especially if if I'm at somebody else's tool that's not similarly equipped.

My good habits were brought home to me one day at work.  I was carrying a cordless drill across the production floor, and happened to notice that I was practicing good gun safety - trigger finger placed along the side of the drill, rather than on the trigger 

Be safe, everybody!


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## Terrywerm (Jan 14, 2018)

I have not yet added an interlock switch either. The key for my three jaw chuck is larger in diameter than the key for my four jaw, and the two chucks use different size square drives, so I would need to make two hangers, one for each key. I still stand by the old habit of turning the chuck, faceplate, or drive dog at least one full turn by hand before starting the lathe.


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## TakeDeadAim (Jan 14, 2018)

Cooter Brown said:


> View attachment 252693
> 
> 
> This looks safe right??


I cant see how this could go bad at all!   I did a similar job where I had welded up some cracks in a spun disk then had to dress down the welds and re polish.  Could have held a pin in my backside the entire time.  Next time I know its just not worth what I was realistically able to charge.


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## TakeDeadAim (Jan 14, 2018)

Saw a classmate cut the tip of his finger clean off when he left the chuck key, which was hanging on a chain, in the drill press.  He apparently hit the switch before removing his hand from the chuck.  At age 15 that message stuck in my head.  To this day I will not hang a chuck key on anything.   Keyless drill chucks everywhere in the shop.  With the lathe I saw and heard it happen shortly after the drill press accident.  Got in the habit of never letting go of a lathe chuck key till its in the rack.  Like someone said above its a lesson everyone should get but only if no one gets hurt.


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## Cooter Brown (Jan 14, 2018)

That was part of a Father's day present I made in 2017 last minute in under 3 hours. Lawn edger from hell


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## TakeDeadAim (Jan 14, 2018)

I'm glad I hate lawns, lawn care, yard work, tree trimming etc.  If you will run that thing I got some serious edging to be done in spring.  Ill have EMS standing by.  LOL


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## tjb (Jan 14, 2018)

Jake2465 said:


> Very first mistake I made when I started running a lathe for the first time. I fired up the lathe and all I heard was something smack the wall about 20 feet away. Come to find out, it was the lathe key. I thought "woah!! if that hit my face I could have been hurt bad" . Never did that again.


I still consider myself a rookie hobbyist, but in my prior professional life, I worked at valuing risk for large corporations.  Over the years, I've found that that training has caused me to subconsciously consider ways to identify and reduce risk in all facets of life - including hobbies.  I've never had the pleasure of soiling myself because I inadvertently left a chuck key in a lathe, but I recognized the danger early on.  A while back, I bought a Harrison M300 lathe that needed a lot of work.  (My philosophy has always been the best way to learn how to 'use' a piece of equipment is to learn how to work on it.).  I quickly noticed the hazard of a flying chuck key on that lathe, and it seemed to me a good machining and wiring project for a rookie would be to fabricate a lathe cover/cut-off switch for it.  Attached is a picture of the result.  I intentionally made it short enough to not cover the business end of the chuck in case I ever wanted to turn an oversized part.  Bottom line is I CAN'T make that mistake on this 1979 model M300.  It ain't pretty, but it works!

Regards


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## tjb (Jan 14, 2018)

hman said:


> I'll start out by saying that I like and appreciate EVERY ONE of the "safety interlock" ides that have been presented here.  But I've hesitated doing this.  I personally prefer to always be conscious and careful, and not get dependent on external devices.  Maybe I'm paranoid, but I'm concerned that I could get complacent, especially if if I'm at somebody else's tool that's not similarly equipped.
> 
> My good habits were brought home to me one day at work.  I was carrying a cordless drill across the production floor, and happened to notice that I was practicing good gun safety - trigger finger placed along the side of the drill, rather than on the trigger
> 
> Be safe, everybody!


"...I personally prefer to always be conscious and careful..."  You must be young.

Regards


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## Dranreb (Jan 14, 2018)

Seems to me that if we could all actually rely on habit, muscle memory and self discipline to keep us out of trouble, not one of us would have ever lost our car keys, mislaid our eye glasses, or stood feeling stupid at a checkout with no money in our pocket.


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## hman (Jan 15, 2018)

tjb said:


> "...I personally prefer to always be conscious and careful..."  You must be young.
> Regards


Just turned 70 last year.  Can't say I was that way (c&c) in years past ... musta been lucky instead


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## uncle harry (Jan 15, 2018)

kvt said:


> I do not get that mag, but remember it thus either on here or youtube or something.



I saw a you tube video recently where the owner of a bench lathe mounted a  limit switch below the bench  top next to a through hole.  It was a small lathe and he wired the limit switch in line with the hot motor lead.


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## Richard White (richardsrelics) (Jan 15, 2018)

I actually like the idea of using a magnetic safety interloc that prevents the lathe from starting without the chuck safely stowed....Having been trained by the formerly politically incorrect Navy on machine shop safety practices, they were not kind nor polite, nor politically correct on what they would do during training if I EVER got caught leaving that chuck key in the chuck.... I have little fear over a few things, my Lord,  my father and that First Class Petty Officer if he was p'od..


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## tjb (Jan 15, 2018)

hman said:


> Just turned 70 last year.  Can't say I was that way (c&c) in years past ... musta been lucky instead


I knew it!!!  Just a kid (at heart).


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## Firestopper (Jan 15, 2018)

Back in HS shop class, Mr. Bishop (RIP) was quick to expel anyone from shop class for any shop safety violations especially chuck keys left in the chuck. He also had that famous poster of the long haired (hippie idiot as he called it) guy with a large portion of his hair missing after getting it caught in the drill press. Anyone remember that poster from the 70's? Anyway, I was conditioned long ago to never violate shop rules.
On the four jaw scroll chuck, I use mini magnetic keys to dial in stock requiring them to be left in place, but the machine's power is off and in neutral.
I still have all my digits approaching four decades of shop work (I need them for counting). Another thing I see in postings are folks wearing open toe footwear in shops. 
I'm not really judgmental as we're all grown dudes but lets use some common sense and self perseverance to continue to enjoy the hobby we so love and enjoy.  I'm not a fan of safety gimmicks like the spring loaded chick key, a interlocking switch maybe but nothing substitutes good practice.
Ok, off my soap box, Turn and Burn fellas (safely).

Paco


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## Elijah Durham (Jan 15, 2018)

Guilty !


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## Jake2465 (Jan 15, 2018)

The other story I heard that involved a lathe chuck was about a lathe operator that had overspun a large one on a CNC lathe. Apparently it flew apart and killed the guy. A huge piece of it ricocheted off the concrete floor (after it destroyed his leg) and shot through the roof of the building.


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## rock_breaker (Jan 15, 2018)

I remember the article on the chuck key having to be in it's holder before the lathe will start. Infact I have encountered a second article on the same subject. My only problem with making such a devise is that I have 3 different chucks with different keys. Haven't got over the laziness to build a 3 pronged safety switch yet.
Have a good day
Ray


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## blue_luke (Jan 15, 2018)

- " I personally prefer to always be conscious and careful, and not get dependent on external devices"
- " I still stand by the old habit of turning the chuck, faceplate, or drive dog at least one full turn by hand before starting the lathe."

It's OK not to trust any 'external device' they are méchanical per definition so a contact can come out lose, a screw missing etc...
THEY WILL FAIL ONE DAY OR ANOTHER this is why verifying this sort of things should be included in your routine maintenance.

BUT!

The good safety habit you seems to have acquired, as fine as they are, YOU WILL FORGET IT ONE DAY OR ANOTHER!  I can guaranty this also.
And that single omission, because you are tired, stressed by production schedule or whatever reason, may hurt you.

So we need absolutely both: acquire the proper habits and reflexes, and install, inspect and maintain a good safety interlock system.
On each machine! The chances that one get distraught and experience a failure of a safety mechanism then becomes about null!

And don't completely trust one or the other, in other words, be weary! I never stand directly in front of the chuck when I start the machine, I never stand in front of the main breaker switch on a new installation and I turn my head away while doing so, wearing leather gloves that goes up to my elbow (here in Canada, our industrial power is 600Vac/3 phases, when you make a wiring mistake, that switch will bark at you in a ferocious display of flames, smoke and explosion!  No joke!

Luc

PS: it is a simple matter to make a two chuck keys holder with microswitches in the safety loop... Come on do it!


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## Captainbeaky (Jan 21, 2018)

I am just about to commission my ( new to me) bantam 2000, and I like the “chuck key lockout” solution a lot. Firstly, it’s a really good idea to have a place for every tool ( and thus every tool in its place, so you know where it is) but it’s a really good idea to lock out the machine if a key is missing.

I don’t disagree that good, careful practice should be the norm, we are human - we will make mistakes. So it’s not a bad idea to implement safety interlocks for obvious (and popular) mistakes.

Oh, by the way, it’s a good idea to set up any interlock switches so they are in the “machine off” position if they were to come loose, or a wire comes off.


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## Skowinski (Jan 24, 2018)

Funny, and scary thread.  First time I was in a machine shop with some large lathes running I looked at the chuck spinning, the size and weight of it, and the speed, and realized you could get hurt really bad.  Then I watched some videos.  I don't want to see those again.

A few months ago with I picked up an Atlas lathe I walked into the garage at the sellers house.  There sat the lathe, switched off of course, but with the key in the chuck......


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## ch2co (Jan 24, 2018)

Took a couple  of pictures for my key in the chuck solution.  The drill is just a quick way to make major adjustments of the 
chuck jaws. Its a small 10" lathe.


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## KBeitz (Feb 25, 2020)

If you make a key holder with a switch make sure it's wired so the lathe 
does not start if the lathe is left on when you remove the key. That could 
also be very dangerous.


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## Karlito26 (Oct 8, 2020)

I did that in shop class. Luckily it hit the lathe bed. My teacher looked at me and shook his head. I used collets the rest of the year.


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## epanzella (Oct 8, 2020)

It just takes training to ingrain in yourself an aversion to certain unsafe things while not depending on your decision making.  Having been around guns all my life, I can't even point a toy gun at somebody without getting that quezy feeling in my stomach. It's the same thing with my lathe key. I can't let go of that key without removing it from the chuck even if the power is off. You get in trouble when you start deciding when an unsafe practice is OK and when it's not. If it's never OK you play it safe by reflex even when on auto-pilot (when most mistakes happen).


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## bluechips (Oct 8, 2020)

As a machinist apprentice at a Gov't Arsenal I was taught  "If the chuck wrench is in the lathe chuck your hand better be holding it".


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