Advice re how to cut down a hollow-core door

[Howard Rosenberg]

Does anyone have good clear instructions on how to cut down a standard borg-bought slab hollow-core door.

Most of my questions are about how to -
- unpack the honey comb inside the door to put the bottom wood back in
- clean off and reinstall the bottom wood back into the door

Also - should I use the TS or a circ saw?

Any other tips would be mighty appreciated.

Thank you.

Howard

[Brian D Anderson]

I've had to do this a few times. I have no idea if it was the correct way or not but . . .

There is a fair amount of wood on the bottom. I've cut them down with a circular saw and a straight edge. Unless you have a really large cross cut sled, I'd stick with the circular saw.

If I go through the solid wood at the bottom, I just take a 2x4 or some other scrap and rip it to the correct size. Glue and clamp it in, sand it smooth . . . prime and paint. I wouldn't be too concerned with the quality of the finish since it's kind of hard to see the bottom of the door. :) I don't remember there being much honey comb at the bottom of the door.

I'll probably be doing this again in the next week . . . I have carpet being installed in my son's room. I already have the doors off and in the basement ready to be cut down.

-Brian

edit: I guess my experience has been with the hollow, raised panel doors. Those usually have solid wood in the bottom rails . . . up to a point. I'm not sure about the flat hollow doors.

[Tom Hammond]

I'm assuming you want to shorten the door, not make it narrower. I've done a number of these.

1. Score the faces of the door with a knife and cut just to the outside of that line to avoid splintering the face. Use a sharp finish blade and cut carefully.
2. After cutting off the top or bottom rail, I simply use a chisel to remove whatever cardboard is within about 2" of the edge inside the remaining door.
3. I generally cut a new rail to fit into the opening, as cleaning up the old rail is a real pain. Fit and glue the new rail, using regular wood glue and spring clamps.

Easy... but still a pain.

I suppose you could do the same thing along the length to significantly narrow the door.

[Prashun Patel]

There's a lot of wood at the bottom. If you have to cut so much off that you're hitting the hollow then my 1st choice is to buy the next shorter door.

If that's not an option, then you can trim a 2x4 to fix inside, using glue and clamps to secure it.

I use a circular saw and guide to cut doors. I also follow with a trim router to shave a very slight chamfer on the bottom. Then I prime and repaint the bottom.

The other option (if the door's not pre-bored and mortised) is to cut equal parts off the top and bottom, so you don't have to cut into the hollow.

[Pat Turner]

I had to hang 20+ new doors when we bought our house. The way I did it was cut the bottom to length with a skill saw, The take a hand held planer and remove the sides from the offcut. Use the skill saw to cut the ends (what had been the vertical pieces) off the offcut. What is left is the perfect sized piece of wood to fit back into the door. My doors didn't have cardboard that low. Glue and brad nail.

In theory ripping a new piece on a table saw would be faster. But the Unisaw doesn't load in my truck easy, and even the saved from the trash job site saw I have would be more of a pain to move arround. BTW, this is a cut (ripping 3/32 off a 1.5" piece) that doesn't look very doable on a festool rail saw.

I remember when I was 16 asking a much older friend about hand held planers. He said they were worthless except for hanging doors. Years latter, when I was faced with 20+ doors, it was a great purchase (specifically a Bosch.) I've also got some use out of it planing trim pieces to make them say 1/32 less wide. Again much easier on a worksite then bringing a table saw, and I'd be scared to leave a $120 blade in the saw overnight.

[Tim Reagan]

The recent doors I have bought, raised 2 panel HC from Lowes, have just over an inch on the bottom of mdf. I could actually just break off the masonite cover from the cutoff piece and reglue it back in the bottom.

[Jim Heffner]

From your post, I assume that you are wanting to shorten the door...is this correct? If so, a couple of things to consider first.(1) How much length to remove from the door bottom, and(2) what material is the door made of?

First thing is to clearly mark the top of the door, so as not to cut the wrong end when laying it on the sawhorses.
Second, clearly mark the amount of the cut to be made and score the intended cut the amount needed with a sharp utility knife on both sides of the door.
Third, I would cover the cut area with blue painters tape ( both sides)
to help and prevent tear out of the door material.
Fourth, measure offset of saw and install a good quality straight edge
and clamp it down on each end to guide the saw.
Fifth, make sure you use a good quality saw blade( prefer a new blade here) and line up saw on the mark and start making the cut. Be sure and take your time, no need to hurry here.
After cut is made, check the cut edge and touch up with a light sanding on both sides of door.Reseal cut edge with a good sealer to prevent moisture from entering the bottom edge of door.Then rehang door and check clearance to floor/carpeting or threshold for proper fit and closure.
If additional material needs to be removed, remove door and make additional cuts to insure clearance. If the door is needing to be cut
a large amount that would be into the hollow area of the door, cut it,
remove the solid piece at the bottom of the door, remove the outer
skin material and re-insert the solid piece back into the door bottom
and glue it into place and seal area as before. Hope this is what you
are needing.........Jim Heffner