Cutting round corner mortises

[Wes Billups]

Wasn't sure where to post this so I thought it'd fit best here. I'm running into a problem where the power tool junkie in me can't find a suitable alternative.

I'm installing quite a few doors in my basement and can't figure out the best method to mortise for the strike plates. The corners need to be rounded and I don't have a round chisel. Since the door frames are already installed, routing them out isn't an option.

How does everyone else cut the rounded corner mortises? I've tried scoring the line with a utility knife but my skill/technique ends up with a very jagged looking curve.

Thanks in advance,
Wes

[Joe Scharle]

Carver's gouge come to mind.

[glenn bradley]

As Joe says; a gouge with the correct radius will do it. http://www.leevalley.com/wood/page.aspx?c=2&p=30024&cat=1,41504

[bill mullin]

I do them two ways.
Sometimes, I use a utility knife. Use an old one (with a good blade), and use your hammer to gently tap the knife around the radius.

Or, sometimes I use a 1/2" spade bit to cut the radius.

[David Prince]

I have a set of these from HF that get you pretty close.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=38458

http://www.harborfreight.com/cpi/gifs/clear.gif

[Andy McCormick]

Its easy, just take a forsner bit that is close to the radius and just lightly drill it. Its that easy. Andy

[Frank Drew]

An in-cannel gouge (bevel on the inside) of the proper radius would make quick work of the corners

[Tony Shea]

I've always used a utility knife with a template of some sort, the latch plate itself or a homemade job. Just keep going over it until it's deep enough and pare away the waste.