What about a
Straight Plunge, router bit ? It is made for a wood router, but the shaft will fit my drill press. I think they are made for cutting wood but perhaps I can find a heavy-duty one. At $15-$20 the price is right. Do you think it is worth a try?
http://www.internationaltool.com/ama...ightplunge.htm http://dwp.bigplanet.com/woodwork/pa...catuid%3D10226