Ripping an Acute Angle

For a tricky millwork installation, the woodworker needs to rip a 65-degree angle on a plywood edge. Colleagues offer solutions. November 10, 2006

I need to make what should be a simple triangle shaped enclosure to hide a post in a kitchen. The problem I have is how to go about ripping an angle larger than 45 degrees over 6 feet. I really need 65 degrees. A sled built at 45 and then set saw to 20? Any suggestions would help.

Forum Responses
(Cabinet and Millwork Installation Forum)
From contributor J:
Are you actually trying to make a 66.5 degree cut for a mitered corner on your triangle? In other words are you trying to miter a 45 degree angle like you would see on the lower corners of a wooden flag case?

From the original questioner:
I am trying to cut three pieces about 6 feet long. One corner is 45 degrees; the other two are greater than that at close to 65 degrees. The home owner does not want what would be easiest a square box. So this was their idea. The 2 small pieces are about 12" by 6', and the long side of it is 22" by 6'.

From Gary Katz, forum technical advisor:
I use a jig for ripping crown molding at a steep angle when I have to do raked ceilings. Here's a link to an article. You could use this type of jig for ripping an acute angle on your columns. Be sure to clamp the accessory fence to your rip fence at both the front and back, and make sure to use a push stick!

Trim Techniques for Cathedral Crown

From contributor B:
I'd build a sled at 20 and set the saw at 45 deg. Depending on your piece, you could also run it like a tenoning jig, and set your saw at 25 deg.

From contributor F:
I don’t know if this will help but for some miters it works. When a table saw is set to zero degrees, in reality the tip of the blade has traveled 90 degrees from the plane of the table.

If you tip your board up so that the narrow edge now rests on the saw table and the wide face is against the fence, you have effectively canceled the 90 degrees or moreover the blade is now cutting at 90 degrees to the edge of the board instead of the face of the board. Now when you crank the blade to an angle, instead of reading the scale on the front of the saw verbatim, subtract the scale reading in degrees from 90 degrees.

In your case, tilt the saw to 25 degrees. If you subtract the 25 degree setting from 90 degrees you will have a saw setting of 65 degrees with the board run on edge. This will give you a feather edge to that the part will ride on from the out feed side of the blade to care must be taken. The parts will also need to be cut to net width and have 90 degree edges before sawing the miters.

From contributor C:
Make a sled and run it in the planer. The sled need only be as long as your planer bed and the resulting miter will be perfect. People who have experience with this technique know it's the fastest, easiest way to produce a razor sharp acute angle.

From contributor B:
Contributor C - you're right about that, as long as your piece can fit through the planer. Milling the glue lines might be an issue. I've done this before by edgebanding the plywood with solid wood, and then milling that solid wood down in the planer like you describe. Although the way I've done it is with a full-length jig, which I realize is kind of dumb now that you mention it!

From contributor C:
Contributor B - next time just make the sled a couple feet long and clamp it to the planer table at a slight angle - with the in-feed end kicked over towards whichever side your guide strip is on. This way the feed roller of the planer will automatically track the work piece over tight to the stop, just like a powerfeed on a shaper.

From contributor F:
I get the feeling that everyone is talking about different methods. I enjoy making jigs to get a machine to do an uncommon operation. There is no way that planing miters on the edge of material is faster than a saw. A sawn miter makes a perfect glue joint if you use the correct blade.
Also, the planer method limits you to one angle and one material dimension per jig. I would not consider that fast or easy. You might find more than a one time use for a 45 degree planer guide or 22 .5 degrees but this guy needs 65 degrees. A saw changes angles in seconds. I have planed angled material only when the planed surface shows in the finished product - never for a glue joint.

From contributor C:
There is no one right way to do things. The size of the material being milled, the number of pieces, the level of finish required and etc all affect the choice of method. For me the circumstances sometimes dictate the planer method. For example, I can use the same 2 foot long jig in the planer for a piece that is two feet long or twenty feet long. It has built in power feed and is much safer than the saw when dealing with large or long work pieces. Also 65 degrees is really just the start of the range for the planer jig, it can go all the way to 0. Whether or not this will work for the particular situation of the original poster, I don't know.

From the original questioner:
Yes I was aware of that method. It is great for rough framing, not so much for finish work.