Hi: The type of style and rail cutter with a bearing are used when using a template to do arched door rails. Bits without a bearing are used with a fence, for straight cuts without templates. Rails require a support when cutting them, like a sled. The important thing with one piece bits is that when you use them they allow both stiles and rails to be cut the same way, that is with the face down or up in both cases.
I use the bit sold by Oak-Park in the raised panel system and it works perfect.
Hope this helps answer your question.. Woodnut65

 

The two piece matched set works the same way both bits stock face down. Some of the adjustable bits Ive seen have two bearings, but I would think atleast one of them is usually removed before using. I have never used an adjustable stile and rail(cope & stick)
bit.

Regards
Jerry

 

Thanks that's what I was looking for.