Thread: Cutting a hollow door

The issue with hollow core doors is that they are actually hollow. Under the 3mm (or thinner) skin, the void is usually just filled with folded cardboard.

A blade like that shown on your circular saw will likely just chew the cardboard leaving a mess inside the door. What you could do is cut well clear of you final intended 75% trim and see what happens.
Depending on how the cardboard is attached to the door skins, inserting a new style might not be an easy process. Hence the suggestion to try an initial cut with your blade and see how it turns out. If you need a finer tooth blade, this will tell you before you completely bugger the door by cutting to the line.

Clamp a sacrificial strip on top and bottom of the door surface and you should get a clean cut. The cardboard filling in the door will be able to be easily pushed back so that you can insert, with glue, a new timber edge and finish the door. You will need to thickness the filler strip to match the door opening.

You have enough excess door material to try a practice cut to ensure that it will be OK.

you could also try just cutting the outer skin initially, so have the blade only protruding 3-5mm, and open up a section and hand cut thru the cardboard smaller than the cut (neater to do it by hand) and then do the final cut through the hidden skins so you don't need to cut cardboard with the circular saw.

Hi Ian, I was hoping to use both sections once cut. We use the same doors at work and they have honeycomb type cardboard inside. What the hell I'll take a cut into the 1/4 section and see what the results are. Thanks

another option ,.....if your moving, somewhere there must be a second hand/ recycling timber year, grab some doors from them and start from scratch,
or garage/yard sales.even op shops

I've had to do this quite a few times, for various reasons. (Usually related to clients with short arms and deep pockets. )

The best results come, as Poundy suggests, when you only just cut through the skin on each side.

I do a full depth cut at each end (being as accurate as I can for position and squareness!) to just sever the top & bottom rails, then scribe a line on each side of the door between these two cuts.

Set the saw to only a few mm past the skin of the door and finish the cuts on each side. I like to use a jigsaw to quickly burn thru the cardboard for final separation, but in a pinch I've been known to use a utility knife, coarse hack-saw blade or even, once, a bread knife. It's just cardboard, after all.

You'll probably lose a few mm cleaning up the edges after you've glued in the new stile(s)... how much depends on just how accurate you did the end-cuts and marked out the lines.

I took a cut into the end of the doors and surprise, surprise theirs no damage to either side. Now to glue on the new end timber and nail into place.
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