Replies

1. 
   wooddood | Feb 15, 2007 10:30pm | #1

   Here's the method I use for odd angle miters. Draw a very accurate full size template and extend the lines beyond the perimeter of the drawing. Use a protractor to determine the angle of the corner. The extended lines give the protractor a longer, more accurate base to work from. Divide by 2 and that'll give you the miter angle to cut the pieces. If the piece you want to make is small, double or triple the scale of the drawing to get a more accurate reading with the protractor. Also, if you can, use a high quality protractor with finely etched markings to get better accuracy.

   You should make some test cuts on scrap and set them on the drawing to see if they line up okay, both for the angles as well as the length.

   Hope this helps some.

   Alan

1. 
   maple | Feb 16, 2007 01:15am | #2

   Thanks
   Joe

2. 
   4DThinker | Feb 16, 2007 02:20am | #3

   I helped a student cut very long compound miters on thick walnut slabs that comprised her chair design.  It was only possible and yet still challenging using a large powermatic table saw and a large compound miter guage like the one you can find here:

   https://www.shop.osbornemfg.com/displayProductDocument.hg?productId=2&categoryId=1

3. 
   BigNat | Feb 16, 2007 03:21am | #4

   Am I correct in assuming you are constructing something with canted sides? (Like a hopper, with compound mitres) If you are, the method described earlier will give you a false result as the angled sides will change the angle of the mitre in relation to the surfaces of the board.
   This is one of the tricky bits when cutting crown mouldings. There is an on-line calculator that can help get your compound angles nailed down. It is; http://www.scarletta.net/WoodJoy/compound_miter.html

   Hope this helps,

   Nat

4. 
   douglas2cats | Feb 16, 2007 04:32am | #5

   If I just have to do a couple of odd angle miters I've found the quickest thing for me is to cut both pieces slightly long, then clamp one on top of another at the desired angle and cut through both pieces with a narrow kerf handsaw.

   If you build it he will come.

1. 
   maple | Feb 16, 2007 04:37am | #6

   That is nice.

1. 
   KeithNewton | Feb 16, 2007 04:59am | #7

   Here is a method that does not require that you even bother to know what the angles are. First draw a full size pattern with both inside and outside dimensions. Then with a good straight edge, and very sharp pencil, draw a line that represents the miter by where the lines cross on the inside and outside of any two adjacent parts. Then lay your actual parts on top of the pattern, and mark both the inside and outside edges of the miter. If you have a TS sled, attach a fresh sacrificial scrap of something like 1/4" MDF on the sled. I like carpet tape, but brads or screws will hold it, then make a fresh cut. Now all you need to do is align the marks with the edge of the kerf in the zero clearance of the sled, and make the cut.I like to assemble the two opposite angles of the sides first. After they are set, you can see if the two opposite sides match, and if they don't, you can still make a pass to adjust one of the angles if it is needed to make a perfect fit.

5. 
   wellis | Feb 18, 2007 06:14am | #8

   Gee guys - I just set my saw at 45 degrees, cut, and join.  It always comes out as a trapezoid.  :-)

   Bill

1. 
   maple | Feb 18, 2007 06:38am | #9

   I have the same issue. However this time I wanted a specific trapezoid.

   Joe

6. 
   JohnH | Feb 18, 2007 05:27pm | #10

   Hello Joe,

   Here's a link for making precision hexagons with compound angles. It works fine. It should work for your trapezoids, whether compound angles or not.

   http://forums.taunton.com/fw-knots/messages?msg=34185.10