Fabricate Neck and End Blocks

I decided to try a mortise and tenon neck to ukulele body connection.  I used my modified mill (router and x-y vise) to make the 1/4" mortise in the blocks.  I thought I could use my 1/8" router bit and run it throught two times to make the 1/4" cut.  It did cut, but I ended up cleaning the mortise with a chisel.  Next time I will use a 1/4" bit to cut the mortise.