Bolt size, thread size, torque, etc. vs. Ratchet size...

[Applesauce]

This seems like a pretty elementary question, but I'm curious: how do you choose what size ratchet to use on a given bolt? If you have a 15mm bolt, for instance, at what torque do you draw the line on using a 1/4", 3/8", or 1/2" ratchet? Do you use some other criterion than torque? At what kind of torque do you worry about shearing the head on the ratchet or breaking the socket walls?Does anyone know if the ANSI specs for ratchets feature the kind of loads they're required to bear?

Does this make sense? I'm really just curious...I'm not worried about my tools! Are there industry guidelines you're required to follow? Or was it part of your formal training? Or have you never given it much thought, and always seemed to know the right tool for the job?!

 

[SlowPoke-Canada]

I see the point of your question but I suspect for most, it's common sense.
I'm unlikely to use a 1/4" drive 9/16" and put my ratchet at risk when I have a 3/8 & 1/2 drive option.
On the other hand, I'm not likely to use my 1/2" drive 8mm impact socket unless the intent is to break the bolt.
I like having overlap options between drive sizes for accessibility issues and obviously, more is gooder.

 

[Provincial]

When I started out working on things (farm equipment and a Model A Ford) all I had for a ratchet was a 1/2" drive set that went from 3/8 to 1-1/8 12-point. I had to be careful not to twist off the small stuff with the 3/8 socket! I didn't get a smaller ratchet for years, and then it was a 1/4" drive. My 3/8" drive set came soon after. i worked on airplanes for 20 years, and rarely needed the 1/2" drive on them.

Once I started a rock quarry, I added 3/4" and 1" drive, because of the size of the equipment.

My rule of thumb is to use the ratchet that applies the required torque to the fastener with a reasonable pull on the handle. If I have access problems, I'll pull harder on a shorter handle in order to get on the fastener with a ratchet. I am slowly moving to long-handled ratchets in order to use smaller drives while keeping the pull on the handle reasonable. As far as I know, there is no official guideline for ratchet pull/torque/size.

 

[sberry]

As you get older you learn to size3 up a bit to make it easy,,, its the main reason for the 3/8 ratchet warranty in general and at the start of a career, my next ratchet lasted a long time.

 

[billymade]

You might check out the Wright tool safety training program; its free, I reviewed it in the past. They have a nice little "make sure to use the right drive size" table:

http://www.garagejournal.com/forum/showthread.php?t=24838

http://wrighttool.com/safety/PDF/safetyEvaluation.pdf

 

[sberry]

My helper will wrestle 20 minutes pulling his guts out with a 3/8, A 3 foot reach and 30 seconds later I got it knocked off with a 1/2.