Using Router to Flush Trim Door Jambs
I’m a homeowner installing new pre-hung doors in my house. My house was built in 1939 and has plaster walls. The walls vary in thickness from about 5″ to about 5 1/2″.
I’m planning to have the doors (TruStile) hung on 5 1/2″ jambs. However, before I do that, I want to figure out how I’m going to trim the jambs flush with the walls where the walls are less than 5 1/2″ thick.
How do pros typically handle this problem? I could probably do this with a jigsaw, block plane, or MultiMaster. What about using a router with a flush trim bit. Running the bearing along the wall should result in a perfectly flush jamb, right? I think the only areas that I wouldn’t be able to do using the router would be the top corners and the bottoms because of the width of the router base.
As a more advanced approach, what about using a Festool MFK 700 with the horizontal base? This would also allow me to do the top corners (though still not the bottoms).
This may be a completely insane/stupid idea, but figured I’d ask. What do you guys think? Thanks.
Replies
The problem you've got here is that you can only trim one side of the jambs. You can't cut the door side at all. Using a router would work fine as far as cutting the jamb, but the issues with the wall may be on the door side. Set the jambs plumb and square to the narrowest part of the wall on the door side. Cut the casings into the plaster on that side. Then you can use a router to trim the other side. Be careful because even with a ball bearing pilot the router could chew up your plaster.
Have used a router to flush-trim window jambs and it worked pretty well. Can't remember too many details, though, because someone else set it up.
Thanks for the info. May end up adjusting my approach once the door is in the RO, but at least I have another option. Guess my idea wasn't as crazy as I thought.
Rough install the frame, mark the wall on the back side, take the frame down and rip with a circular saw.
Some carpenters use a belt sander, some a skillsaw and others use electric hand plane. Personally I like to use an electric hand plane, but care has to be used on corners since a plane can bugger them up quickly if the tool isn't kept nice and flat with pressure on the rear.
In some cases if there's a lot of material to remove I'll pull the jamb apart completely and rip each part separately on the table saw.
I'd guess an electric hand plane is about 20x faster than a multi-tool, 6x as fast as a belt sander, and all together a must have tool for finish carpenters.
Will Keep You Posted
The doors are on their way. Once I get them in, I'll have a better idea as to the approach I want to use. Appreciate all the suggestions. Will let you know how it goes and post some pics. Thanks.