Making Molding

[Paul Canaris]

I’ve noticed most commercial molding has a back cut (a thin portion removed from the back). Is this necessary, what is its purpose? I am in the process of making base and cove molding for a renovation project, and I am wondering if this step is necessary as it requires quite a bit more effort.

[Don Abele]

Paul, it's called a relief cut and allows the moulding to follow any imperfections (contour) in a wall. I make a lot of my own moulding and always cut a relief cut on the back. The larger the moulding, the larger the relief.

Be well,

Doc

[Paul Canaris]

Don, I don’t own a purpose made relief cutter. Can I simply use a dado set for this?

[Peter Quinn]

Its pretty tough to simulate a thru feed molder (5-7 head) in a small shop. Those relief cuts help out a lot with install. You might even be able to get a set made for a jointer which might be worth your effort on longer runs.

I use a dado stack to make them in my own shop, though you can get some for an Amana 40MM head if you have a shaper, the whole set up costs under $150 with a starter set of knives. A Magic Molder for the TS might also be an option, and a power feeder will speed things up considerably.

[Don Abele]

Don, I don’t own a purpose made relief cutter. Can I simply use a dado set for this?

Absolutely Paul. Whether you use a dedicated relief cutter, as I do, or you make the cut with a dado set, you always make the relief cut first.

If making it with a dado set, you need a good feather board (or board buddies) to hold the stock firmly against the table to get a consistent depth to the dado.

The exact size/amount of the relief depends on the height/thickness of the stock. I typically make mine 1/8" deep for moulding up to 3/4" thick. Anything thicker than that and I'll usually go up to about 1/4" deep. For width, I typically leave 1/2" at the top and bottom of the profile. So on a standard 3 1/2" base moulding, I'll mill a relief that's 2 1/2" wide.

When nailing it's important to nail through the full-thickness areas, not the relieved portion.

Be well,

Doc