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Truncated pyramid

5K views 8 replies 4 participants last post by  TooPicky 
#1 ·
Yet another seemingly simple shape is impossibly difficult to cut. What I need is a box where all 4 corners are mitered, so you don't see any end grain. I also want it to taper big to small, (pyramid), and to be flat on the bottom. (truncated)

So, it's pretty east to cut the first 45, with a taper. But to get the mirror on the other side, and get it accurate, so the corners look good, I don't know. I've already discarded making the tapered pyramid shape as a pattern, and using a 45 degree router bit to get the bevel. The bits and equipment aren't big enough to do the thickness I want.

Ideas?
 
#4 ·
You can make the cut on your table saw. Adjust your miter gauge to the angle of the pyramid wall and the table saw blade to the angle for the 45. The important thing to remember is that the correct angle to get a 45 degree joint is not 45 degrees. I don't remember the math for figuring out the correct angle, but it is only 45 when the walls are vertical. You could probably use google to find the formula for a compound angle.
 
#5 ·
Yes, I considered that, too. But, you would have to tilt the mitre gage the opposite way to get the other side. Which you'd have to do perfectly in order for the joints to come out right. And, if the piece slid AT ALL on the gage, it'd also ruin the cut.

Crap, I forgot about the angle thing. I do recall now, though. I have little to no experience with compound miters.
 
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