Drilling 2 3/8" holes in 8" wood posts...[[ ??? ]]]

[PILOON]

Have also made spade bits using old skillsaw blades and 1/2" rod for the shaft.
I made a series of rosettes to decorate door frame corners.
The saw blade steel kept a decent cutting edge.

Milwaukee does make up to 3" (have one) bit for the hole hawg, awesome bit that can fill a pail with chips in about 2 mins.
Those bits are not cheap but sure do a great job.

 

[Mace Canute]

I have made spade bits before for situations like this. Doesnt take long. Piece of flat steel, and a grinder with slicer disc to rough out the shape and leave a nice point, then put a bit of an edge on it. Then weld to a piece of 3/8" or 1/2" round bar.

Dont have to be hard steel, and dont have to be perfect for drilling wood. It wont cut as well as an actual spade bit or as well as them fancy bits, but dont cost anything either if you have a welder, some steel, and about 1/2 hour to spare.

I've done the same thing to make exact sized counterbores in wood for large washers and to bore out rotted off fence post stumps. Worked like a charm!