Jig for miters over 45 degrees?

[bobby_m]

I'm doing some trim work that requires miters that add up to less than 90 degrees. Of course, both my CMS and BT3 only miter to 45. Before I got the BT3, I got by using a square to shift my work by 90 degrees in the CMS, but that was really dangerous. I suppose the same idea can be used on the BT3 using the SMT, but has anyone made a jig that provide a more sturdy base rather than holding a square against the fence.

I started building one by screwing a 14" x 20" piece of 1/2" MDF to the SMT and running it through the blade to establish the cut line. Then I attached a wood fence to it with a pivot near the cut line. I then began systematically laying out miter angle lines on the MDF in 5 degree increments. I made a few test cuts and the miters are accurate, but I think there's got to be an easier way. BTW, The reason I wanted the work to be supported all the way to the cut line is that some of the molding is thin and delicate.

Side comment: Isn't it confusing that a cross-cut is 90d to the length of the work but all the saws label it as zero on the miter gauge? If I want to miter two pieces to form an inside angle of 80d, I have to miter at 40d on each piece. However, this really equates to an angle of 50d on the miter gauge of any saw.

Bobby

[LCHIEN]

...
Side comment: Isn't it confusing that a cross-cut is 90d to the length of the work but all the saws label it as zero on the miter gauge? If I want to miter two pieces to form an inside angle of 80d, I have to miter at 40d on each piece. However, this really equates to an angle of 50d on the miter gauge of any saw.

Bobby

Yes, it is. I suppose the difference is between a miter and a taper; they're 90 degrees complementary of each other.

For angles less than 15 degrees I'll use a taper jig (that rides against the rip fence):

http://www.harborfreight.com/cpi/cta...temnumber=1382
$10-15 at Harbor freight, $20 everywhere else.

For angles between 15 and 45 degrees it depends a lot upon how long and how wide the piece is. I'll build an L-shaped jig; the bottom of the L goes against the miter fence and the long side of the L supports the workpiece.
The L being 90 degrees the fence and holding the workkpiece, you turn the miter fence 20 degrees and you get a 20 degree taper cut after taking the difference from 90 you note.
A small vertical on the bottom is needed to be clamped to the fence and the length of the bottom of the "L" depends upon the width of the piece at the end of the cut. These almost always have to be custom made. You can also tilt the L away from the blade or towards the blade, again depending upon the shape and width of the piece. Tilting the top away is best because then the crook of the L supports the piece. The other way you have to add a clamp to hold the piece.
I'll try and take a pic of my solution for the angles.
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OK, here's one of a similar jig I used for my bandsaw (the blade is on the opposite side of the miter fence so its a mirrir image of what you'd use on the BT3) shown here cutting a 10° wedge from the darker piece of wood.