Cutting 45 degree angles on large stock?

[jmilligan]

I want to make a small book shelf with 45 degree cuts on the sides and top to form a 90 degree corner joint. The sides are 20" wide by 4' tall. The top is 30" wide. What is the best way to do this on a 520 to support the stock while making these angle cuts? Thanks for any advice.

[shipwright]

On my current project I've done it with a simple sled. The 45 deg is very accurate if you just rip a square and cut it diagonally. The larger the square, the more accurate the 45. My project is smaller than yours but my 10 ER table is smaller than yours too. I'd just build a larger one for your larger work. There are more photos of this sled in operation in my thread: http://picasaweb.google.com/paulm549/Cu ... directlink

Tack a strip on the bottom to follow the miter slot
[ATTACH]10218[/ATTACH]
Cut your 45's
[ATTACH]10219[/ATTACH]
Assemble with room for saw to re-cut your edge
[ATTACH]10220[/ATTACH]
Add clamping bars
[ATTACH]10222[/ATTACH]
Cut your pieces
[ATTACH]10221[/ATTACH]

EDIT: I just noticed that you have a sliding crosscut table. That should make this even easier.

Paul M

[mickyd]

On my current project........ The 45 deg is very accurate if you just 1. rip a square and 2. cut it diagonally.
Paul M

Paul,
We newbies wouldn't mind you elaborating on these two steps....

[shipwright]

Well Mike...
1) Set your table saw at anywhere you like, don't have to measure. Cut a piece of stock that wide. Turn it 90 deg and cut it again without changing the fence.

2) Draw a line on the resulting square from one corner to the diagonally opposite corner of and cut the line.

Is that really what you were asking?

Paul M

[a1gutterman]

Paul,
We newbies wouldn't mind you elaborating on these two steps....

Hi Mike,
I think that what Paul is trying to make clear is that IF your saw is alligned properly, you can cut a perfect square of plywood or, perhaps, MDF, and cut this perfect square diagonally (creating two identical pieces that provide 45 degree angles), and to use those two pieces to create the jig.

[dusty]

After you cut on that diagonal line you "presumably" have too EQUAL 90° right triangles.

Paul probably does this without giving it a lot of thought. Good luck!:)

[mickyd]

Well Mike...
1) Set your table saw at anywhere you like, don't have to measure. Cut a piece of stock that wide. Turn it 90 deg and cut it again without changing the fence.

2) Draw a line on the resulting square from one corner to the diagonally opposite corner of and cut the line.

Is that really what you were asking?

Paul M

Since your procedure was described so basically, I'll have to ask what will most likely be a series of questions.

1) and 2) So your not using the miter gage?
2) You freehanding the 45? That's the only reason I can think of the need for a line being drawn.

[shipwright]

No no miter gauge is required, just the fence.
Cut on the bandsaw. Miter gauge is only 6" long. The diagonal line is over a foot. Less chance for error. (if you can follow a line).

Paul M

[mickyd]

Why gee.....hope you didn't type your fingers to the bone with that detailed elaboration.. Seriously, I don't understand how an accurate square can be made without using the miter gage.

Also, I don't know if I can maintain a straight enough cut on the 45 degree over a couple feet using the bandsaw. Maybe I can but just don't know it. I know that when I cut the taper angles on the 5" long x 3" thick poplar, my cuts weren't perfectly straight. They were horrible but weren't dead nuts either. Maybe bandsawing thinner (>1") stock it's easier.

[JPG]

Actually Paul is using a presumed square piece. The rip one way, turn 90 degrees, rip second way createsa workpiece which is a parallelogram with equal sides. Assuming it is rectilinear, a corner to corner cut would be 45 degrees. It would need to be cut way off the diagonal to create a significant error to the 45 degree resultant angle.