Installing a picture frame spacer to best eliminate gaps at the corners is an acquired skill. When you order a spacer cut to fit, we miter it to fit inside the rabbet with a very small allowance. The problem is that no matter how tight the tolerance is, it’s almost impossible to completely eliminate a gap at the corner.
To make tight corners we suggest the following procedure (see diagrams below):
- Put the first piece of spacer in backwards; this piece can be up to about 1/8″ undersize
- Now trim the second piece so it is ¼” shorter than the frame dimension and put it in backwards, ensuring that the point is pressing tight against the first piece of spacer; this piece can also be up to about 1/8″ undersize
- Repeat step 2 on the third piece
- For the last piece you will finally have to make a precise cut, so that it fits tightly in between pieces 1 and 3. However, since there are points on both ends it can be a whisker (that’s a technical term that means a very small amount) long and you will still be able to force it snugly in
If ordering cut-to-size spacer with your chop or frame, you will need to order it “cut long.” This is because only one side of spacer has a finish on it and we expect you to install it conventionally. If we cut it long you will have enough length to reverse the miters.