How NOT to throw your lathe chuck key through the windshield of your Porsche!

[nightowl499]

Super idea! I'll give this idea serious consideration when I finally re-wire my M300 Harrison lathe with a VFD. Right now I don't want to spend the national dept on propane to heat my shop.

Move to florida I never ever have to heat my shop ,

 

[uncle harry]

This seems like a really good way to manage the risk.

can one of you electrical types help me figure out the wiring on my G0752 so I can add this to my lathe? I'm not sure if it is going to be exactly the same as the G0602 but that would cover a lot of us home shop folks.

jim

The usual safety features of a stop/start circuit such as E-stop, brake, chuck guard etc are wired in series. The lathe chuck safety feature can be included in this "chain" of switches. It can be located anywhere between two of the safety switches or between the last switch & the contactor or relay in the circuit. The circuit is commonly called a latching rung in hard-wired relay logic.

It may be important to note that the control wiring is usually around 120 VAC so proper protection from shock is essential.

I "Googled" the G0752 manual & found for a G0602 that a good place to insert the chuck safety switch is between the start switch terminal 3 and the stop button terminal 2. Remove the red wire between them and replace it with a 2-wire cable or 2 wires to your added chuck safety switch. Connect one wire to the normally closed switch terminal.

For the G0702, a good place for the chuck safety switch is to replace the red wire on term 1 of the on button switch term 4 to the E-stop switch term 1.

For my lathe I'm considering using square tubing for the chuck holder to make it easier to adapt and mount the switch.

 

[shoeboxpaul]

Fantastic idea.
:thumbzup3:

 

[Shadowdog500]

Nice solution to an age old concern.
I admit to once making the dreaded error on a lathe. I inadvertently hit the on switch with my elbow with the key still in the chuck, it simply fell out within the first quarter turn and hit the floor. I am not saying leaving the key in the machine is in any way safe, it could have been much worse, say if the key didn't fall out it would have collided with the bed and bent and possibly caused damage to the chuck, gears or bearings. Or worse, if a body part was between the key and bed... Just saying, the key didn't fly out of the chuck with great force, as I once feared it would. That being said, I think I will add the safety disconnect feature to my machines.

I have the older 11x36 belt style lathe like the one George Wilson was talking about. I hit the power switch once while I had the top open with my hand in the machine changing the belts around to adjust the spindle speed. Luckily I'm in the habbit of unplugging the lathe before doing anything to the drive belts, but I turned white when I noticed what happened anyway. A switch like this on the lid would also come in handy. I also got in the habbit of pulling the belt tension lever Foward when I'm adjusting the chuck. this way it won't turn at all if I inadvertantly bump the power. And it makes it easier to rotate the Chuck while tightening it.


This chuck key switch is a great idea!


Chris

 

[extropic]

I think that Roy's interlock for the chuck key is a clever idea.

I have a concern that it might reinforce the fundamentally unsafe practice of leaving the key in the chuck (because it's "safe" on this lathe). When Roy goes to his buddy's shop, to use his buddy's lathe (without interlock), will Roy remember to alter his awareness?

I might plagiarize the electrical interlock feature but with the addition of something that reinforces the key should be "in the holder" if not in use. For instance, off the top of my head, I would consider adding a bright red flashing light (in an obnoxiously obvious location) that is activated by removing the key from the holder. Don't want to be annoyed by the flashing red light . . . put the key back in the holder.

There is no argument that those who have learned to keep there hand on the key when it's in the chuck are doing it right.

Maybe most importantly, The OP has got some of us focusing on our safety procedures again. Thanks Roy.

 

[herbet999]

Great idea. I strive to never leave the key in the chuck. No matter if I'm about to start the lathe or not.

 

[sk1nner]

At work we have magnetic chucks mounted horizontally to buff hydrolic pistons after bronze plate. They are foot switch controled. The magnet is turned on and off with a long Allen wrench. About 9 years ago I was using the mag buffer and didn't remove the Allen wrench before I hit the foot pedal, the wrench wiped around caught my shirt and jabbed me very hard in the stomachache. Shirt was shredded and I ended up with a softball size bruise on my stomache. To this day any new people we have run that buffer I tell that story to. A few of my coworkers have habits of leaving keys in tapeing machines and I am constantly grabbing the keys and throwing them into hard to reach places.I figure if they can be rude about safty I can be rude about them having to get on their hands and knees to find the key. A switch like that would be awesome, nice work!

 

[pdentrem]

Good idea and simple to do. Lots of our equipment at work have interlocks for good reason. Anything can and has happened before. The aviation industry tends to build on the accidents of the past to make things safer for the future. FAA not withstanding.

Habits are easy to make on a keyboard but in real life it takes time and continual reinforcement, just like training your dog or cat.
Habits can be interruptted by a fleeting moment of distraction. I hate stamping presses (we have a few) as that moment of distraction can be costly, no matter how safe you think you are. Interlocks or not.

Remember that anything made by man can be defeated by man, either on purpose or by complete blind luck.

Here is a thought. You are away and you are not home to be in control of your equipment, what happens if someone else decides to use the lathe. Since they are not a regular user of a lathe and have a bad habit or two, maybe they leave the chuck key in the chuck. The lathe will not start up and no ones gets hurt. Without the interlock, the lathe will operate and who knows what happens. Since this is a place of business the nasties will come down on you and try to blame you for the accident that was not your fault. It happens, we have all seen it, read about it, etc. Having the interlock is not a bad idea no matter what the other 11 pages of comments had to say, Porsche comments included.
Pierre

 

[Terrywerm]

There are many good points brought up here and I do not disagree with any of them. However, I utilize a much simpler solution: Before turning on the power, I always rotate the chuck one full turn by hand. This ensures that the chuck key is not in the chuck, but also verifies that there are not any other clearance issues such as jaws hitting the ways or anything like that. That step is so engrained in my head that I even rotate it one turn if I have not made any changes at the chuck.

 

[rbertalotto]

I always rotate the chuck one full turn by hand. This ensures that the chuck key is not in the chuck, but also verifies that there are not any other clearance issues such as jaws hitting the ways or anything like that. That step is so engrained in my head that I even rotate it one turn if I have not made any changes at the chuck.

This is a great tip for a Sunday morning. A great habit to get into, regardless of what you do with the chuck key...Thanks!

Here is a thought. You are away and you are not home to be in control of your equipment, what happens if someone else decides to use the lathe. Since they are not a regular user of a lathe and have a bad habit or two, maybe they leave the chuck key in the chuck. The lathe will not start up and no ones gets hurt. Without the interlock, the lathe will operate and who knows what happens. Since this is a place of business the nasties will come down on you and try to blame you for the accident that was not your fault. It happens, we have all seen it, read about it, etc. Having the interlock is not a bad idea no matter what the other 11 pages of comments had to say, Porsche comments included.

THANKS!