Left a spacer block in the 3-jaw

[vascon2196]

Very embarrasing...I used an aluminum spacer block to help machine a flywheel on a four jaw chuck. I forgot to remove the spacer before I turned the lathe on. It "flew" past me and a few of my students. No one was injured thank God but I was very upset with myself.

It should have never happened.

Chris

 

[bearcar1]

Whoa baby!!! That got a lot of attention, I'm sure. If it had been the chuck key, you would have been given an "F" for the class and sent home. (at least that is how machine shop class was in my day) (how long ago was that? don't ask.) My instructor was excellent and he really only had one or two beefs that he absolutely would not tolerate and that was one of them. Laying the chuck key down into/on the lathe ways or allowing the key to sit in the chuck while doing something else at the time was another. It was way too easy to get distracted and forget about it before turning the machine on, thus launching it half way to Mars. I'm certain you don't do these types of things on a regular basis Chris, but I can certainly appreciate your embarrassment. It only takes a split second for all Hell to break loose and it has happened on at least one occasion to all of us no matter how vigilant and careful we may be. Glad no one was hurt in your class, use the episode to reinforce the need to for safety and careful practice, your students won't forget it.


BC1
Jim

 

[vascon2196]

I had an old instructor who would literally leap across desks, lathes, etc...and slap the chuck key out of the chuck if it was left there. He would say nothing except run across the shop wherever he was and slap it out of the chuck.

After all of that I still forgot to take the block out prior to turning on the machine. :-[

 

[Ned Ludd]

Hi Chris,
What you need to make is a series of discs with four radial slots the thickness of your jaws. What you do is leave the disc in the four jaw, to act as a parallel spacer when machining an item that is too short to touch the chuck. The slots of course stop the spacer from flying out. I have three, approx 6,10 and 15mm in thickness and when used singly or in pairs I can hold most items. Mine are made from 3" Dia. alloy and the slots leave about 3/4" in the middle, to stop it falling apart.
I find them quite useful, so others might also find the same.
Ned

 

[Tin Falcon]

Chris no harm no foul. the students got to see you human side. yes push safety on them and keep you head on straight.sometimes getting the students attention and them seeing you as human goes a long ways to them listening to you.
Tin just my $00.02

 

[rake60]

Don't feel too bad about one miscue Chris.

A machinist who has never thrown a shim, block or entire part out of a machine has not
turned on many machines.

It is not a question of "if" but "when".

That is why we teach multiple safety practices.

Never take your hand off of a chuck key.
Always check the chuck for material and debris.
If it's a variable speed drive start slow and then speed up to the working RPM.
Never stand in line with a chuck or grinding wheel when starting it up.
Let the work piece spin for short while and watch for wobble or any indication of a weak set up.

You can unintentionally break any one of those rules and the others will still be effective safeguards.
If we break multiple rules it can become dangerous.

Rick

 

[vascon2196]

Thank you...thank you...and thank you.

 

[mklotz]

When I was starting out I accidentally started the lathe with backgear engaged and the link pin not withdrawn from the bull gear. It scared me badly so I decided to make a lockout for the power switch. On my lathe there's a knob just above the switch and it was easy to cut a piece of plywood to hang on that knob in such a way that a slot in the wood prevents the power switch from being operated.

Over the years I've worked hard to mental and muscle train myself to always put the lockout in place before doing something dodgy - installing hand crank, using loose parallels, etc.

I can't tell you how often I've reached down to turn the lathe on and said, "WTF is this damned piece of wood doing here?" Inevitably, finding it in my way makes me step back and recheck everything before removing it and powering up.

If such a mechanical lockout doesn't fit with your lathe, think of adding another switch in series with the power switch. Mount this switch in an awkward, out of the way location or provide it with a lockout.

 

[Jim E]

In the past I have made a spring that fits tight on the chuck key and sticks out past the square about a quarter inch. You have to give a little push to get the square into the chuck, but it is pretty much impossible to leave it in the chuck. Just adding my 2 cents.

Jim

 

[steamer]

ah yes the "launch the object across the shop with the lathe trick"

YEP...been there done that.....we are frail we humans aren't we? 8)

As Rick and others have said.....when not if....and don't feel too bad.

Those are the lessons you don't soon forget though....and your students probably won't either which is a VERY good thing to come from the incident.

I hope it scared the @(&$%(* out of them.....

Dave

 

[vascon2196]

I think it scared the #$%^ out of everyone. I definately won't forget about it.

Thank you to everyone regarding your safety advice.

Chris

 

[BenPeake]

I had an experience similar to this about a week ago in my four jaw.

I was using four pieces of 1/4" HSS as spacers and I removed them (well I thought I did - I heard them all drop). However, one of them dropped into the chuck! I thought everything was ok, so I turned it on and it must have been 20 seconds before the piece flew right past my ear - much quicker than a chuck key flying out as the spindle accelerates up to speed. I had my lathe spinning at around 1400rpm, so it was traveling pretty quick. I expect it would've done some damage if it made contact with me. Now I make sure I have accounted for every piece before switching on the lathe. Thanks for sharing,

Ben