Shaft Key Material

[murphy12]

I have a nonstandard keyway due to space constraints and I'm woried about compression. Is there any reason I can't stray away from standard keystock (1018 or 1045) and use something harder like 4140 Q&T?

 

[MintJulep]

You run the risk of damaging the shaft in the event of an overload. Keys are intended to be sacrificial.

 

[murphy12]

Thanks. I though that was the reason, but I was wondering if there were any other reasons.

 

[ornerynorsk]

There is no reason that you can't use a harder material, I've used hardened keys in the past with much success. Just keep in mind what mintjulep said, but you almost always have some repair considerations when a key shears, regardless of material.

 

[MintJulep]

murph,

These types of things work pretty well if you have the space.

http://www.fennerindustrial.com/products/trantorque_ind.html

 

[savis]

This is an interesting question. However, you should be careful to consider what the industrial mechanic will replace this key with if they have a failure of some type. We recently had some issues with keys fretting and found out that our stock room was stocking 6x6 keystock material incorrectly (using 6x6 square stock c-1018. The tolerances are greater +0/-0.078, whereas keystock is +0-0.030.

Savis