cutting straight edge in wood with dremel

A Dremel isn't the right tool to cut wood, particularly wood that thick. They're really not intended for wood; not nearly powerful enough. A circular saw, with the right blade would work much better. A fence clamped to the frame would help a lot.

Actually they are intended to cut wood. I have a router attachment for my Dremel. Have only tried it a couple of times but not used for any projects. It is rather nice, but the bits are small.

Personally, I wouldn't try using a Dremel. I'd probably use a jig saw, preferably with a board clamped/nailed to the frame as a guide. If a guide isn't possible, I'd draw a line and follow as best as possible. In either case - ANY case, actually - you'll need to smooth and clean up with a plane. I wouldn't use a circular saw...too heavy, agressive and too small an area to rest saw even if you take off the door(s).

See above.

This is a project ideally suited to the Harbor Freight Miracle Multifunction tool (with a "fence" clamped to the work).

Seriously, for what this tool does, it has no peer. You'll find new uses every day! Not long ago, I found the tool could mix up an oil and vinegar dressing so the two ingredients didn't separate!

I was thinking about the cut-off wheels. Routing a straight line with a Dremel is going to be a *major* challenge. It's simply the wrong tool for the job.

Use a circular saw (with a "fence" clamped to the work).

You'll never get a straight line.

Useful tools, to be sure, but this isn't one.

"above" says you are stopping 2" short of the walls, you have to do some sort of a finishing of the rough edges of where you are cutting back to the old dimension. A diagonal taper, or something.

Correct. I was thinking of just a perpendicular cut (parallel to the walls).

It will cut a line as straight as the Pope. And he won't have to remove the door as he would if trying to use a 15-pound circular saw.

That's exactly what I mean.

Four screws.

Yep. In the past week, I used a Dremel on a cabinet door. I used the tool to cut the heads off the screws holding the door in place as it was petrified by at least three coats of some god-awful paint.

Once that awfulness was out of the way, I was able to vise-grip the screw stubs to remove the suckers.

Good grief. These things from the bronze age?

Early '60's for sure.

Anyway, that process turned out to be too much work and too time consuming. I searched for a better way.

At first I tried incantations hoping for a miracle. Inasmuch as I had been a bad boy all week, my prostrations and entreaties evidently fell on deaf ears. (I considered a burnt offering, but then thought, "Nah".)

I finally settles on slathering a hefty dose of fuming methylene chloride. The screws surrendered. All turned out well.