Duplicating a diagonal cut?


I am building a cabinet that is 40" across the back, the right side is 25" and the left side is 8". The front is the resultant diagonal. (It will go in a corner...) There is a top and two shelves; I am leaving the bottom open. It was easy enough to cut the top; I just clamped a straight edge and cut it with a circular saw. I planned on doing the same with the shelves, but am a little concerned about getting them as precise as they have to be with such equipment; if the angle is not exactly the same as the top, it simply won't fit. Then it occured to me that if I cut the shelves a bit oversized and carpet taped them to the top along the front edge (reversing the diagonals of course) they would form a rectangle (or nearly so). If I then ran the whole thing through the table saw, my angles would have to be exactly right; and cutting the right size would just be a matter of setting the fence right.
However, I am a little concerned about running something held together by carpet tape through a table saw. If it pulls apart it could be quite a mess; though I don't see why it should pull apart.
Every try something like this? Any other suggestions to get the shelves to be exactly like the top?
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I use double faced tape all the time for a variety of cuts on a variety of equipment. Getting the tape off is difficult; I've never had the items come apart while cutting them. I've learned to use smaller pieces of tape so that I can break the bond when I'm done! :) When I have a piece that has no straight edge and it needs to go through the TS, I just slap on a straight piece of wood with...you guessed it...double faced tape.
Be sure to get rid of ALL the tape residue before finishing your project.
Dave
toller wrote:

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Did you consider using the top as a _guide_ for cutting the shelves?
lay the top on the shelf, mark the diagonal. slide the top 'over' (keeping it precisely aligned with one of the 'square' edges, until you have spacing that exactly matches that of the circular saw (from the blade to the edge of the baseplate). Voila!
Note: do test-cuts on some scrap first, to make sure that the measure from guide to blade is accurate.
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Cut the first piece to size, then the remaining pieces a little oversize. Tape the first one to one of the oversize pieces and trim to exact size with a router and a flush trimming bit. Trim with the grain and score it if you are trimming across the grain to reduce chipout. If you want to spend extra money, get a compression, spiral flush trim bit to really reduce chip out. However, a quality, sharp carbide works well. I am assuming it is plywood.
Preston.

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Cherry. But the router idea is worth thinking about, thanks
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Method 1 ======If you don't already have one, make yourself a cutting guide for your circular saw, as described here: http://www.taunton.com/finewoodworking/pages/w00035.asp
Mark the cut line by tracing along the diagonal of the top, align the cutting guide exactly with the mark, clamp it down, and cut.
Method 2 ======Mark the cut line as above, and cut slightly oversize (1/32" to 1/16") with circular saw, or bandsaw.
Then attach the top to the shelf board with carpet tape, and use a bearing-guided edge trimming bit in a router to trim the shelf to exactly match the top.
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
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This was one of the reasons a router and flush cutting bit were invented....
Clamp it and cut it.
I can almost guarantee they will be identical.
toller wrote:

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