What is the purpose of the "cheeks" on a bench plane?

[Jeremy Vonk]

I hope this isn't a ridiculous question, but, what is the purpose of the cheeks on a bench plane? Is it for turning the plane on it's side and using it with a shooting board? I'm asking because I work in a machine shop and I was thinking about trying to make my own plane and I just want to think through all of the design considerations.

Thanks!

[Chris Fournier]

They are structural! The sole has an almost through hole in it and the cheeks provide support for the sole in this area, the mouth of the plane. Lucky for us we can also use them to put the plane on it's side and shoot with it.

[Derek Cohen]

Rigidity. Keeps the sole flat and not flapping around.

Regards from Perth

Derek

[Jim Koepke]

All the above and they are part of the aesthetic appeal. The Bailey curved sides is appealing to my taste. The Bedrock flat top does nothing for my senses. Lee Valley's Veritas planes have nice looking sides.

Every plane doesn't have to be made to use on a shooting board. Many planes have had curvy sides including some made by Lee Valley.

jtk

[Sean Hughto]

They often aid in directing the plane as references for your fingers or in holding the plane when using it in atypical application where you might be pulling or inverting the plane.