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JCDammeyer's 42 projects

Sad story here. Don't know if it's just the left over head cold or all the political stuff messing with my mind but I made what could have been a very serious mistake yesterday.

I was cleaning up the mill vise and tweaking the adjustment screw. Didn't like the backlash against the back bearing section so thought I'd make up a spacer washer since the threaded collar wouldn't go in any further.

Simple right? First a flat washer in the 3-Jaw with appropriate bits to make sure it stayed square. Then tried to bore the hole to enlarge it to 18.5mm. Broke the tip of a carbide insert. Hmmm. Here's where things went further south. Tried a boring tool with welded carbide cutter. Snapped the tip off that too.

OK must be a hardened washer. Chuck in a piece of aluminum casting. Bore with the other side of the chipped carbide insert. Terrible surface finish. And it appeared wobble even more. And now the carbide tip was also chipped.

What the F? Hey. How come the chuck has almost complete unscrewed. Maybe I forgot to tighten it up after the last set of changes and photos for registering chuck to spindle and it was wobbling and that broke the carbides. Tightened it up.

Tried boring again. Terrible surface finish. Disconnected the belt drive and waited for the chuck to stop. That's when I realized it was turning the wrong way.

Somehow, when I switched on the lathe I had turned the direction switch and nothing had happened. No idea why the spindle didn't turn on. Switched the spindle on/off again and then it started. OK. Some strange anomaly. I'll look into it later.

And there was the mistake. I've never run the spindle in reverse and the ON/OFF switch is red while the direction switch is black. No idea why I did that and didn't clue into it.

Once the spindle was turning in the correct direction and with a new aluminum cutting insert and the boring went fine. Facing went fine. Parting off the washer went fine.

I hesitate to think what would have happened if the chuck had unscrewed just that little bit more and the damage(injury) it could have caused.

I think I was lucky.
 
jcdammeyer said:
I think I was lucky.
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This is one reason I love the VFD running my mill. I set the acceleration rate deliberately slow enough so I can see which way it is turning. My brain is hardwired to watch it spooling up - no idea why!

Maybe you need a backup beeper..... LOL!

IMG_0485 (1).gif
 
Susquatch said:
This is one reason I love the VFD running my mill. I set the acceleration rate deliberately slow enough so I can see which way it is turning. My brain is hardwired to watch it spooling up - no idea why!

Maybe you need a backup beeper..... LOL!

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The VFD does run my mill. And it doesn't accelerate/decelerate all that fast. But if the operator looks at the situation and doesn't register then it doesn't matter. My mind was clearly somewhere else. In hindsight, 20-20 being what it is, there were so many signals that something was wrong. In 16 years the chuck has never unscrewed and turning pressure should force it to screw on and tighten.

What is scary is that I thought I was aware of what I was doing.
 
Its a good thing you are aware of the severity of the situation that could have unfolded, and even being "aware" of the situation isn't always enough. That is why various machines have guards, interlocks, stops, etc. as no matter how "careful" you are you can still make an error.
My takeaway from this would be to do the following:
1. look into adding a lock to the chuck so that it cannot unscrew, or disable reverse if you cannot lock the chuck in place, or if you still want reverse and can't lock the chuck, make reverse a double actuated position (i.e. need to flip a spring loaded interlock out of the way to enable reverse.
2. add a lighted indicator for direction that is selected.

I've had to take a course called Human Factors a few times as it relates to aircraft maintenance, and "complacency" is one of the factors. Its just that you become expectant that the lathe will be rotating in the correct direction that you didn't notice it was not. The remedy should be to put in "engineering controls" to prevent an issue - hence the lock or disable/interlock. The light is not a failsafe but is a useful indicator.

I learned a hard lesson about machine safety about 20 years ago with a table saw without a blade guard. won't say more about that unless asked.
 
DavidR8 said:
Hand held routers scare the bejebuzz out of me. Likewise jointers.
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Hand held routers and my dad....

He wanted a light switch on the log cabin wall and the electrician wanted a cavity for it first. Mom had warned him not to touch her machines, but he could not resist making a very small cavity in the log wall. The electrician had told him to use a plunge router. Every member here can picture it......

Hmmm, needs to go right about here, just squeeze this here trigger thingy and then Yeeeowwwrrrooomeeeyoweyowewooommeeeewoooroeeewowww till mom pulled the plug, then followed by "Oh My God....." 6 Rosaries, and a wall art carving that will last forever on half of the wall.
 
For me anyways, the real lesson learned was that machine / safety equipment / etc. aren't only there to protect you while you are paying attention. They're there for when you are not. And not paying attention can mean looking away for just a split second, or not realizing your chuck is spinning backwards. Sure the safety features help keep idiots safe, but they also work for smart distracted people. PPE has its limits to what it can do for you.
I'm not the safety police, I make suggestions when I see something unsafe but I won't stop you if you insist.
In this case - having a lathe that can reverse, but no way of keeping the chuck from loosening seems like a bad combination. I would think that even the possibility of ruining the job you are working on if using in reverse would be enough reason to ensure it can't loosen, and safety comes along for the ride.
 
Mike R said:
For me anyways, the real lesson learned was that machine / safety equipment / etc. aren't only there to protect you while you are paying attention. They're there for when you are not. And not paying attention can mean looking away for just a split second, or not realizing your chuck is spinning backwards. Sure the safety features help keep idiots safe, but they also work for smart distracted people. PPE has its limits to what it can do for you.
I'm not the safety police, I make suggestions when I see something unsafe but I won't stop you if you insist.
In this case - having a lathe that can reverse, but no way of keeping the chuck from loosening seems like a bad combination. I would think that even the possibility of ruining the job you are working on if using in reverse would be enough reason to ensure it can't loosen, and safety comes along for the ride.
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Good point. So far no one on the South Bend group has come up with a method keeping the chuck from unscrewing. Not without a major rework of the machine.

With that said it may well be the best solution is to disconnect the switch to make it impossible to turn in reverse. Except of course using the 5C collets doesn't have that problem of unscrewing. But as yet I've never in the over 20 years I've had this lathe I've never run it in reverse.

From July 2005. Can't believe it's been this long.
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