Trimming doors

Gday,
Doing some rennos to the house, and finishing off by replacing all the old flat internal doors with 4 panel jobs.

Problem being in my 40 year old house, the old doors appear to be slightly odd sizes.

For example one door is 810 mm, whereas the standard new four panel is 820. There are 3 or 4 different size doors around the house, but all seem to be in between the commonly available door sizes.

I was planning on just buying bigger doors and trimming them down to size, however this has proved nigh on impossible to do with any accuracy using my circular saw, or even my little GMC table saw.

Any advice on how to trim these would reaaally get me out of a jam. And if not, where would I start to look if I wanted to find a tradie with the gear to cut them to size?

Thanks in advance

Lindsey

Hi Lindsey

Usually the best way to reduce the width of a door is with an electric planer taking off about 2mm at a time. I would measure the old door and then mark the width on the new door and draw a line on both sides of the door and plane it down to the line. I would measure at the top and the bottom and transfer those sizes to the new door.

Another way to do it with the circular saw would be to get a straight edge the length of the door still draw your line on the door and then measure the distance from the edge of the sole plate on the saw to the tooth on the left hand side of the saw and then set the straight edge that distance from the line on the door and cut the door with the sole plate of the saw up against the straight edge and cut the door down.

I would then clean it up with a hand plane in either case.

I wouldn't try to do it on the table saw because number one that saw would be too small and the other thing the door may not be parallel.

Also I would take the timber off the lock side of the door.

I take it that they're not hollow core four panels. If they are, then you shouldn't take too much off unless you're re-edging them. I think they recommend no more than 5mm each side.

If the original door is a good fit with all even margins I would lie the new door flat, place the old one on top and trace around it, then plane it as the others said, using your saw on top or bottom. I think once you decrease each side of the door by more than 6mm you get into problems with door warranties.

I have taken a little more than 6mm from each side style and have been prepared to take the risk, the only other option being to get the doors specially made.

Ive always done it with a small circular saw, Just lay the door down and chock up the side you are cutting, set the guide to the distance and cut. A light sand on the edge and good as new. Always found it a lot harder to get neat with a planer and takes more time.

Hi,
Thanks for all your advice, plenty of things to try now.

Yep they are hollow core doors, but I think most of the doors are only about 10mm out, so 5mm off each side should do it.

Router will do it too - clamp a straight edge to the door and follow it with your router. You can never over cut then (make sure your clamps are nice and tight though - so no slipping).

Re-do the door jambs to suit the new doors...:2tsup:

But seriously... if you've ever wrecked one of these doors, the perimeter is a timber frame, usually the same width in from the edge as the thickness of the door. In the middle of the side marked "lock" or "handle" is a piece about 4-5" wide and about 6-8" long. The rest is just cardboard glued on edge, snaked around the guts of the door.

This should now give you an idea how much you have to play with when trimming the edges. The straight edge idea is the best, but use a thin straight edge and cut with the body of the saw / largest part of the sole plate over the door, not over the offcut. This give you the best chance of keeping the cut square, even with an el-cheapo saw.