Messages and Online Forum Q&A

Re: mitering baseboards

From: info@builderswebsource.com
Category: Carpentry and Framing
Remote Name: 63.198.181.43
Date: 26 Dec 2001
Time: 09:57 AM

Comments

Any number of things could be causing your mis-alignment of the baseboard miters. These include:

1) Wall out of plumb (vertically)

2) Wall corners not at a 90-degree angle (use a variable protractor to measure this and make adjustments for each cut). For example, if a given inside corner is at a 93-degree angle, then each miter will have to be at 46.5 degrees. Bosch makes a handy digital protractor (DWM40L) available from Amazon.com for this kind of work.

3) Saw out of alignment. Be sure that you have checked and double-checked the saw on all axes to make sure that square means square, and that a 45-degree angle is truly 45 degrees.

4) The baseboard could be moving during cutting. Be sure to secure it firmly with a clamp during operation. Be careful not to damage the wood.

A few additional questions will help:

1) What is the size and brand of the compound miter saw? How old is it?

2) What is the width and thickness of the baseboard? Are you laying the baseboard flat (wide) side facing down in a horizontal position? If so, the saw blade should be set to be perpendicular to the material (90-degrees) and the tilt of the blade should be +/- 45 degrees depending on whether you're cutting an inside or outside miter. There are usually detents to help make sure the angles are set correctly.

Your problem sounds like either the walls are out of plumb (you can verify this with a level), or that the saw blade is not perpendicular to the material as it cuts. This would explain the top of the miter being OK, but the bottom diverging.

Now, to avoid minor imperfections in miters, many professional installers cope all inside corners using a coping saw. This is somewhat trickier for the novice. Basically it involves cutting one corner of the trim flush with the wall (easy) and the second piece (the joining piece) with a 45-degree miter then back-cutting along the countour of the trim. If your trim has a complex profile, this is exacting work that requires practice and patience. However, the advantage of coping is that minor imperfections are less noticeable and the joint can be filled with caulking for a first-class, tight finish.

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