View Full Version : Miter Cuts
01-02-2001, 02:03 AM
Looking for an easy way to make accurate miter cuts for picture frames, cabinet doors, box lids, etc. Any ideas, tips or tricks would be appreciated....
01-02-2001, 11:08 AM
Well first off your CMS is usually NOT accurate enough for this. A CMS is designed to cut molding for trim, not picture frames. When you cut moldings you only need two pieces to mate and the miter is on the narrow portion of the wood. An error of ½° in the saw is invisible. But when you cut a frame the errors are cumulative so with eight miters that same ½° is multiplied into 4°. Additionally the miter on the frame is on the wide part of the board so the angular error has a longer baseline to work on and you get a significant gap.
Professional frame shops use a "Lion Miter Trimmer" which is a precision knife that you use to 'clean up' the cut from your CMS into a "perfect" miter. Rockler has it in their catalog:
#22460 - Lion Miter Trimmer - $270
This is a *very* expensive tool for just occassional use.
For beveling edges on small boxes you can get a router bit with a precision angle on it. You should precut the bevel on the TS to get it close and then use the router bit as a "clean up" to give you a precise angle. They are available in other angles as well so you can cut hexes, octagons, etc.
#24784 - 11¼° Chamfer (16 sides) - $30
#24791 - 15° Chamfer (12 sides) - $30
#24798 - 22½° Chamfer (octagon) - $30
#24805 - 30° Chamfer (hexagon) - $30
#91551 - 45° Chamfer, ½" high (square) - $19.50
#91573 - 45° Chamfer, 1¼" high (square) - $42.50
(Again from the Rockler catalog)
For small boxes usually finger joints or thru dovetails are preferred for strength. You can make a simple box joint jig: http://www.netexperts.cc/~lambertm/Wood/lynnjig.html
The above jig doesn't require a dado blade and doesn't suffer from cumulative errors like "pin" type box joint jigs do.
There are also a variety of sleds you can make for cutting miters on the TS or RAS.
You can also get special right angle miter gauges (#36461 - $30) for cutting both pieces or you can get a precision miter gauge for your saw ( http://www.netexperts.cc/~lambertm/Wood/incra.html ).
Finally you can use a disk sander to touch up a CMS miter to make it tighter. There are also traditional planer jigs for this as well.
So as you can see there are a lot of solutions to this common problem.