Slotted Hex Nuts

Good Vibrations

February 16th, 2018

Last week we discussed left-handed thread and its staying power on rotating machinery. This week we’ll continue on the topic of tightness as we discuss slotted hex nuts.

Like left-handed nuts, slotted hex nuts are used on rotating machinery because with vibrations, you want something that is going to stay put. You could go the left-handed nut route, but more often than not, you’ll probably use a slotted hex nut. Slotted Hex Nuts are considered the industry standard.

Slotted Hex Nuts are ALWAYS used with a cotter pin – it’s the only nut with a mechanical locking action. As I was talking with our resident engineer, Kevin Connolly, I was asking why you’d want to use a Slotted Hex Nut instead of a left-handed nut. It seems like the more parts you need, the more cumbersome putting the machine together would be. He agreed, but whereas a left-handed nut is stronger in rotating applications than one with right-handed thread, the slotted hex nut with a cotter pin gives you more confidence that the nut will not fall off.

Because of that piece of mind, Earnest sells different types of Slotted Hex Nuts. We have the standard Slotted Hex Nut which is more cost effective. The Hex Jam Nut is available, but because it’s thinner it’s considered slightly weaker. We also have the traditional Castle Nut, which some may think is synonymous with Slotted Hex Nut, but in fact, are two separate things. A traditional Castle Nut is thicker and therefore adds strength.

So I asked Kevin between Slotted Hex Nuts and Left-Handed Nuts which is better and the answer is, it’s personal preference! If a designer likes left-handed nuts over Slotted Hex Nuts, that’s what’s used. However, once the decision is made and the machine is built, that nut should be used going forward (i.e. no changing from a Slotted Hex to a Left-Handed Nut). 

Applications:

  • Grinding Wheels

  • Lathes (both Wood and Metal) 

  • Stamping

  • Engines (Automotive, Agriculture, Construction)

Are there other applications not listed above? Any preference between Slotted Hex Nuts and Left-Handed Nuts with righteous indignation behind it? We’d love to know! Sign into your web account and write in the comments below!